CA1179778A - Method for encoding electric signals obtained during scanning of a graphic pattern having a mixed content of text and pictures - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A method and circuit arrangement for encoding electric signals are provided for the scanning of a graphic pattern having a mixed content of text and pictures, In a first analysis the boundaries of a region are determined, The scanning signals are then subjected to a second analysis to determine the region content. The results of the region analyses are evaluated for determining a code and an accuracy statement. On the basis of the evaluation of all code statements and accuracy statements, one of at least two predetermined codes is selected for encoding the region.

Description

~ ~79778 BACKGROUND OF THE INV~rION
Field of the Invention The present invention relates to encoding techniques, and more particularly to a method for encoding electric signals which ~e obtained during the scanning of graphic pattern with a mixed content of text and pictures.
Description of the Prior Art A method is known from the German published application 2,516,332, for encoding electric signals which are obtained during the ccanning of a graphic pattern having a mixed content of text and pictures which is characterized in that the graphic pattern is subdivided into sub-regions and a picture code is used for encoding electric signals obtained during the scanning of sub-regions essentially containing picture portions, while for the coding of remaining sub-regions, a text code îs used.
Picture codes and text codes can be selected from a multiplicity of known codes according to different criteria in such a manner that as favorable an encoding as possible of the picture and text regions is guaranteed.
Typical criteria for the selection of a code are, for example: a small requirement for memory space or transmission time for the code signal generated by encoding; small suscepti-bility to interference of the code signal; optimum quality--according to aesthetic or other viewpoints--of the graphic pattern which is reproduced from the code signal by decoding;
and compatibility with standardized codes.

~ 1~9778 Typical text codes are described in ~e article "Facsimile Run Length Coding Using Run Length Prediction" by P.A. Stern and W.E. Heinlein in the Siemens Research and Development Reports, Vol. 3 (1974), No. 3, and tynical picture codes are described in the article "Adaptive Delta Modulation Systems for Video Encoding", by T.L.R. Lei, ~. Scheinberg and D. L. Schilling in the IEEE Transactions on Communications, Vol. COM-25 (1977~, pp. 1302--1314. The text codes discussed in the first-mentioned article can, as is shown t~erein in an example, also be used for encoding drawings. As is shown in a further example,they are also suitable for encoding black and white pictures which, as is customary in graphic patterns, are printed in a raster method, whereby different levels of gray are represented by larger or smaller black or white dots on a bright or dark background. The encodin~ of half-tone pictures by ~he text code set forth in the Stern and Heinlein article is, however, advantageous only under the assumption that the resolution or sharpness of the scanning suffices for the reproduction of the position and size of the raster dots. The same also holds true for the encoding of color pictures which consists of several color components printed over one another.
For such pictures, the methods set forth above as well as the method of the present invention, can find use in two alternative obvious variations:
a) with the help of color filters, each color component is detected indlvidually or is calculated from a red/green/blue (R~B) scanning signal as is provided by a color T.V.camera with the help of a color computer which, according to pattern of a known color T.V. coder, forms a ~ ~ 797~8 linear combination characteristic ~or each color component out of thé three components of the RGB signals;
each color component will now be encoded accGrding to the method which is suitable for black-white pictures whereby "white" is interpreted as "white"
and "colored" is interpreted as "black"; and b) only the chrominance signal is encoded, whereby parts of the pattern which are different from white are interpreted as "black" regardless of their color, so that, of course, this method cannot reproduce the color values of the original in the code signal.
However, it can also be advantageous, when the scanning sharpness suffices for the resolution of the print raster, to use one of the codes described in the article by Lei, Scheinberg and Schilling for encoding half-tone pictures.
However, in an advantageous manner, with the use of a further development as set forth in the German published application

2,516,332, of the method described therein, which is characterized in that the scanning signal to be encoded with the picture code is obtained by scanning with a decreased sharp-ness such that the raster structure of the graphic pattern is suppressed, whereby the scanning signal of decreased sharpness is recovered, where applicable, from the scanning signal of undecreased sharpness with the aid of a computer which copies a scanning of decreased sharpness.

~ 179778 Another further development of the known method is characterized in that a scanning signal obtained during the scanning of a sub-region with unknown content is encoded with a text code and the same scanning signal, or a second scanning signal, is encoded with a picture code, that the two code signals obtained are intermediately stored, and that the code signal encoded with a text code is used in the case that its length is not greater than the product of the area of the sub-region and a predetermined proportionality factor, while other-wise, the code signal generated with the picture code is used.
The use of this further development is, however, advantageous only under the assumption that the scanning sharp-ness suffices for the resolution of the raster in which the picture content of the graphic pattern is printed; in other words, the same is sufficient for the reproduction of the position and size of the raster dots.
If the above assumption is fulfilled, then, on the one hand, a picture region will be encoded with a picture code having a great probability, while, on the other hand, even when such a region is encoded by a text code, no impairment of the picture content will occur due to encoding. Only the sub-regions in which a false decision was made during encoding will be encoded with a longer code signal than necessary.
However, if this assumption is not fulfilled, tnen, on the one hand, during the encoding of a picture region with a tex~ code, frequently such a short code signal will arise that an encoding with a text code takes place; on the other hand, the encoding of a picture region with a text code will bring about a significant falsification of the picture content which ~ 179778 will noticeable in the picture which is reproduced after decoding by the occurrence of large black or white spots. When, herein, "encoding of a sub-region" is discussed, the encoding of an electric signal is understood which is obtained during encoding of the sub-region. When, furt~er, the "scanning signal of a su~-region" is discussed, then the scanning signal is understood which is obtained during the scanning of the sub-region.
SUMMA~Y OF THE INVENTION
The object of the present invention is to provide a method for the selection of a code for encoding sub-regions, which is improved with respec~ to kno~m methods, which is suitable even for such patterns and/or scanning models in which the known method fails. In addition, the present invention has the object of providing a refin2ment of the encoding in this direction: that a selection is made possible not only between two codes, namely, picture and text codes, but rather also between several codes for picture and/or text.
The above objects are achieved, according to the present invention, in a method for encoding electric signals which are obtained during the scanning of a graphic pattern with a mixed content of text and pictures which is characterized in that, in an analysis of a first kind (boundary analysis), at least one sub-region within the graphic pattern is detected, that ~he scanning sîgnal originating from the scanning of a sub-region is subjected to a following analysis, or several following analyses of a second kind (region analysis), that the results of the region analyses are evaluated for obtaining, in each case, a code statement and where applicable a backup statement and, that based upon an evaluation of all code and backup state-ments, one of at least two predetermined codes is selected for encoding the sub-region.
The present invention offers the advantage that a method for the encodillg of electric signals which are obtained during the scanning oF a graphic pattern with mixed content of text and pictures is made available which is suitable also for such patterns and/or scanning models whereby the methods heretofore known :fail.
According to another broad aspect of the invention there is pro-vided a circuit arrangement for encoding electric scanning pulse signals obtained from scanning a graphic pattern having a mixed content of text and pictures, comprising: a scanning value decoder including a signal input for receiving the scanning pulse signals, a signal output and a reset output, and operable to produce output signals at said signal output representing recognized scanning values and reset signals at said reset output representing end of scan; first and second interval decoders connected in series, each of said interval decoders including an input, a thresllold value circuit having a respective thresllold connected to said input, and first and second decision outputs, said first decision output of saicl first interval decoder connected to said input of saicl seconcl inteIval decoder, eacll of said interval decoclers operable to procluce OUtpllt sigllcllson said decision outputs re~resenting tlle magnitu(lc? of thei:r i~ ut siglla:Lsin relation to their tlrresllold values; a three-st;lge ;nterv;ll coullter, each stage including all input connected to a precleter~ led clec:ision OUtpllt,a reset in~ut connectecl-to saicL resc?t outllut of said scallll:i llg clc?coclcr, ~mcl an Outpllt; a calculatillg :register For calculating a characte:r:ist-ic n~ll)er, including data inputs conllectecl to saicl co-lnter outputs, allcl an output Eorthe characteristic number; a code selection sw:itcll For selectillg a coclc?;
and a decision circuit connected between said out1-ut of sa:id calculatillg regis-ter and saicl code selection switcll for contrc)ll:illg cocle selc?ct:ioll in accordance \~ith the characteristic n~mlber.

3~3i~

According to another broad aspect of the invention there is provided a circuit arrangement for encoding electrical scanning signals obtained by scanning the graphic pattern having a mixed text and picture contact, comprising: a scanning device for producing scanning signals in digital form; a first buffer connected to said scanning device for storing the digital signals; a first analysis device connected to said first buffer and operable in response to buffer content to determine the limits of regions within the graphic pattern; a second analysis device connected to said first analysis device and to said first buffer for analyzing the region content within the limits of the region determined by said first analysis device; a decision device connected to said second analysis device and operable in response to the analysis of region content to determine which of at least two predetermined codes is to be used for encoding the determined region; and an encoder connected to said first buffer and to said decision device for receiving the digital signals from said first buffer and encoding the same in accordance with the decision of said decision device.
BRIEF DESCRIPTION OF TIIE DRAWINGS
Other objects, features and advantages of the invention, its organization, construction and operation, will be best understood from the following detailed description, taken in conjunction with the accompanying drawings, on which:
Figure 1 is a plan view of the sub-division of a graphic pattern M into sub-regions Tl--Tll which, with the exception of the sub-region T4, are partially bordered by wllite blocks Wl--W16 and partially by a column boundary S;
Figures 2 and 3 illustrate typical arrangcments of scanning dots in the same graphic pattern in each case;
Figure 4 schematically illustrates a mode for a two-dimensional quantization;
Figure 5 illustrates scanning signals Sl(t) and S2(t~ of the two - 6a -7 ~

first lines of a sub-region;
Figure 6 is a table having, altogether, nine two-dimensional ~uantization intervals;

- 61~ -1. 17g~'~8 FIG. 7 is a schematic illustratîon of the structure of an exemplary embodiment of a circuit arrangement, or, respectively, a flow chart, for executing the method of the present invention;
FIG. 8 is a schematic representation of a graphic pattern having a rectangular sub-region T;
FIG. 9 graphically illustrates the energy spectrum of a text region;
FIG. 10 schematically illustrates the energy spectrum of a picture region;
FIG. 11 graphically illustrates a print raster whereby the locations of black raster dots are characterized by dots and the locations of white raster dots are indicated by circles;
FIG. 12 is a quantization table for 3 x 5 two-dimensional intervals; and FIG. 13 is a schematic illustration of a device for the statistical evaluation of the scanning values.
DESCRIPTION OF THE PREFERRED EMBODIME~TS
As was set forth above, FIG. 1 illustrates an exemplary embodiment of the division of a graphic pattern M
into sub-regions Tl--Tll with the exception of the sub-region T4, are, in part, bordered by white blocks Wl--W16 and, in part, by a column boundary S. It is assumed that the sub-regions Tl--T3 and T5--Tll can be determined corresponding to a method set forth in the German published application 25 16 323 because of these boundaries. It is further assumed that the limits of the sub-region T4 are previously known and 1. l7s~a can be adjusted manually for the purpose of encoding. The limits Gl and G2 indicated in FIG. 1 result in the case of the use of a device described below by the realization of a method practiced in accordance with the present invention.
FIG. 2 and FIG. 3 illustrate, as was also previously set forth, typical arrangements of scanning dots for the same graphic pattern. Associated with each dot of the graphic pattern is a pair of coordinates (x,y), the origin of which was selected in the left, upper corner of the pattern.
The orientation of the coordinate axes x and y were selected as illustrated. In FIGS. 2 and 3, in each case a selection of scanning dots in two variants of a column-related and line-related arrangement, and further, the limits of a rectangular sub-region are illustrated. These limits are to be interpreted in that all scanning dots lying within the limits belong to the same sub-region.
The graphic pattern is scanned with the aid of a suitable device, for example, with a video camera or a facsimile scanner, for example, with the video camera described in Computer Design, Vol. 18, March 1979, p. 225, having the designation "C-1000" or the facsimile scanner described in Auerbach, Guide to Facsimile Equipment, p. 50, publlshed in 1975 by Auerbach Publishers Inc., 121 N. Bond Street, Philadelphia PA. 19107, with the name "Model 500" (transmitter), at whose output the electrical signal obtained during the scanning, in the following designated as a scanning signal, stands ready in a digital form or an analog form. The term "digital", is understood in that the scanning signal is ready in the form of a sequence of digital code words which, in general, state the local brightness of the pattern for each dot of a regular do~ raster (scannîng dot) as characterized in FIGS. 2 and 3. The code in which the scanning device states the brightness of the scanning dots will be designated in the following as a "scanning code". In the following, one proceeds from the assumption that the scanning code is not compressed, that is, in each case a code word having an n bit length reproduces the brightness of a scanning dot with an accuracy of 2n brightness level, where _ is a natural number. As a compressed scanning code, a code is designated from which, by means of decoding with the help of a known method, for example, a method described by Stern, Heinlein: "Facsimile Run Length Coding Using Run Length Prediction", Siemens Research and Development Reports, Vol. 3 (1974), No. 3 or in Lei, Scheinberg, Schilling: "Adaptive Delta Modulation Systems for Video Encoding", IEEE Trans. on Communications, Vol. COM-25 (1977) pp. 1302--1314, a scanning code, ~hich is not compressed, can be obtained. The scanning signal is now supplied to an analysis of a first kind--where applicable after conversion of the analog form into a digital form--for example, with the help of an analog/digital converter which is known per se.
In the analysis of the first kind, at least one sub-region is detected within the graphic pattern, that is, the limits of the sub-region--represented, for example, by the coordinates of two opposing corners of the sub-region--are made ready in a digitally-coded form. The standardization of the coordinates of the dot within a pattern is, in itself, unimportant with respect to the present invention. However, it is recommended to undertake the orientation of the two 1 ~79778 coordinates x and y as indicated by the arrows in FI5, 1, whereby the origin of the coordinates coincides with the left, upper corner of the pattern. In the case that the scanning of the pattern takes ~lace line-by-line and within a line point-by-point, it is recommended to use as a unit of the x-coordinate the distance of two neighboring scannin~ dots and as a unit of the y-coordinate the distance of two neighboring lines.
Corresponding to a method set forth in the German published application 25 16 332, it is advantageous to use white blocks and/or print column limits as limits of sub-regions. As is known according to customary language usage, an element determining the limit of a region, for example, a ~arden fence, in general is to be seen as a constituent of one of the regions which it limits in ~he German published application 25 16 332, however, nothing is said regarding the sub-regions which a white block limits that it is seen to be as a constituent of or, respectively, whether the white block is encoded with a picture or a text code in the case that the white block is detected as a limit between a picture region and a text region.
The lack of such information in the German published application 25 16 332 is based on the fact that the decision for the one measure or the other measure under the requirements described above for the use of a method of the German published appli-cation 25 16 332 is not important. This applies to a limited degree, also, for the present invention.
However, it is also practical to see a limiting white block or portions of the same as a sub-region and to encode the same with a selected code. For this purpose,prefer-I 1797~8 ably a code comes into question which otherwise is provîded for the encoding of text regions.
Another ad~antageous method for encoding a white block region is that a scanning dot of a white block in each case is assigned to that one of the sub-regions which it limits and from which it is least removed. Regarding this, it is to be noted that frequently, also, white blocks are located on the limits of print columns as indicated in the upper half of FIG. 1. A difference between the use of print columns and the use of white blocks consists, for one thing, in that print column limits can be used only as vertical limits of sub-regions, whereas white blocks, on the other hand, can be used as vertical and horizontal limits, and, secondly, in that print column limits at least for a specific kind of pattern, for example, a newspaper or maga~ine, in general, have a uniform position with respect to the pattern and, t~erefore, can be set ahead of time, while white blocks, in general, can be determined by means of an analysis of the scanning signal (further above called the analysis of the first kind).
For clarification, in FIG. 1, differently-limited sub-regions are illustrated. For example, the sub-region T2 is limited on all sides by the white blocks, the sub-region T6 is limited on three sides and the sub-region T7 is limited on two sides.
It is advantageous in using the method described in the German published application 25 16 332, according to which, preferably, white blocks are used as sub-region limits to connect the analysis of a first kind which leads to the determination of sub-region limi~s, where applicable) with the 3 ~79778 decision between the selection of a first code Cfixed code) for encoding of the sub-region (decision A) and the further analysis of the sub-reglon (decision B).
According to the invention, the decision A takes place when the sub-region is limited rectangularly and at at least two opposing sides by whlte blocks and/or column limits and t~e distance of opposin~ white blocks falls below a preset minimum value. This method rests upon the fact that pictures in graphic patterns of a specific kind do not fall below a specific minimal extension either in the horizontal direction or in the vertical direction. However~ it is not out of the question that in pictures themselves, white blocks appear. It is therefore advantageous to make the parameters of this decision, namely that these of the mentioned minimum value as well as the number of the white blocks detected as limits, adjustable, so that an optimum compromise can be made, where applicable, dependent upon the kind of pattern to be encoded, between the efficiency and the accuracy of the method of the present invention.
In the case of the decision B, there takes place at least one analysis of a second kind according to a method suitable for the same for each of the sub-regions detected in the analysis of the first kind. As soon as the results of the analysis (es) for a specific sub-region is available, by means of evaluation of these results, the decision is made as to which code is to be used for encoding the sub-region.
As soon as the decision is present concerning the code to be used for all detected sub-regions, one continues, where applicable, with the detection of further sub-regions as l 179778 described ahove. This process is repeated until the total graphic pattern is sub-divide~ in sub-regions without gaps and a code is determined for each sub-region.
It is advantageous when specific method elements of the method of the present invention--be it in the detection of sub-regions, be it in the detection of an optimum code for a specific sub-region--are replaced by means of the withdrawal of the data which would occur as a result of the method step from a data memory or by manual adjustment, in the case that the data in each case are known.
It is advantageous when the data memory for a specific kind of graphic pattern, for example, for specific magazines or specific pages of a magazine, is filled with data which are characteristic for this kind of pattern. This applies, in the general sense, for a manual adjustment. For this, the operator adjusts a specific type of encoding, for example, "only picture code for this and that page" manually. This can result in an advantageous gain of time in specific cases.
The encoding of the sub-regions with the code determined in each case or, respectively, the generation of the code signal, as well as its transmission to a memory or to a partner can, according to a measurement of the available buffer memory and computer capacity, occur at any later point in time, sequentially for the individual sub-regions or simultaneously for several sub-regions. It is, where applicable, advantageous also to generate an encoding of a sub-region with several different codes or with a preferred code already before the determination of the code which is to be used for this sub-region, to store the code signals and, in each case, after 1 lL7977~

determination of the code to be used for the sub-region, w~ere applicable, to generate the code signal not by new encoding but rather by selection from the stored code signals. This method also makes possible an advantageous gain of time.
As was already set forth above, FIG, 7 illustrates schematically the structure of an exemplary embodiment of the invention for circuit arrangement or, respectively, a flow chart ~or the execution o~ ~he method of the present invention. By scanning the pattern M with the help of a scanning device A, a scanning signal is obtained in digital form and via an output 3 of the scanning device A is stored in digital form in a first buffer memory Pl by way of its input 4. The storage occurs, for example, such that a selection of scanning dots of the pattern M arranged line-wise and column-wise, as illustrated in FIGS. 2 and 3, to each scanning dot, in case eight-bits of the memory are associated which state the pattern brightness in this dot. It is assumed in this example that, because of the limited capacity of the first buffer memory Pl, first only a partial section, for example, a strip Sl of the patt~rn, is scanned and stored. The lower boundary of the strip is designated as SlR.
A first analysis device Al sub-divides the strip into sub-regions in which it takes scanning values from the first buffer memory Pl via its output 7 and subjects the same to an an~lysis whose results are the limits of the partial regions or, respectively, the limits of white blocks which, for their part, limit the sub-regions. Where applicable, the strip Sl is determined to be a single sub-region. By way of an output 23, the first analysis device Al transmits to an encoder CD the l ~7977~

limits of sub-regions for which a decision is already possible in favor of a specific code to.be used for the encoding of the sub-region because of their dimensions and their boundaries according to the method of the present invention, as well as, where applicable, the identification of this code.
The encoder CD, if required, takes over from the first buffer memory Pl the scanning values obtained from the sub-regions, encodes the same with the use of the identified code or a stipulated code and stores the code signal which is generated in a second buffer memory P2 from which the output is provided to a further memory or to a partner. Scanning values obtained from white bloc~s must not absolutely be transferred from the first buffer memory Pl, but rather can, where applicable, be replaced by a uniform white value.
The limits of those sub-regions for which a decision is not possible in favor of a specific code according to the above method are transmitted by the first analysis device Al via an output 10 to a second analysis device A2 which derives analytical results for each sub-region from an analysis of the scanning values originating from the sub-regions which are taken via the output 6 of the first buffer memory Pl and via an output 14 and provides the same to a decision device E.
This makes the decision, which of at least two preset codes is to be used for encoding of the sub-region, in each case, and provides the identification of this code to the encoder CD which carries out the encoding of the sub-region, as described above.

~ ~ 79778 As soon as the encoding of the sub-regions detected in the strip Sl of the pattern S and the transmission of the code signals in each case into the second buffer memory P~ is concluded, the scanning of the pattern stri~ S2 occurs adjacent to the strip Sl and the transmission of the scanning values obtained are input into the first buffer memory Pl.. With this, the scanning values originating ~rom the stri~ Sl can be overwritten if the subdivision undertaken by the first analysis device Al of the strip Sl into sub-regions was complete. The lower limit of the strip S2 is designated into FIG. 1 as G2.
It is advantageous that pattern elements of the analyzed segment or, respectiyely, strip, under certain circumstances are not associated to a sub-region but rather to a so-called residual class. This will apply particularly frequently for pattern elements which are located on the lower edge of the strip. In this case, according to the present invention, one proceeds as follows. the scanning values of the sub-strip of the strip Sl next to the strip S2 (SlR in FIG. 7) in which the scanning values are located which are associated with the residual class are kept in the first buffer memory Pl and--in the case of limited memory space--the strip S2 will be selected to be correspondingly narrower so that the scanning values of both the sub-strip SlR and the strip S2 may be accommodated in the first buffer memory Pl.
This is indica~ed by the different sizes of the strips Sl and S2 in FIG. 1.
Followi.ng this, the analysis and encoding of the scanning values stored in the first buffer memory Pl takes ~ ~79~8 place, to the extent that t~e same do not belong to a sub-region which is already detec~ed and encoded.
The sequential description ~ the method of the present invention does not exclude the possibility that with respect to a saving of time, several of the method s~eps described above occur simultaneously. For example, during the analysis of the second kind of a sub-region, an analysis of the first kind can occur for the determination of further sub-regions. Also, during the analysis of the second kind of a sub-region, the encoding of another sub-region can take plaee whose optimum encoding was already determined. Finally, it can be advantageous to apply the method ~ the invention for carrying out analyses of the first kind and the second kind both for the encoding of sub-regions simultaneously on several sections of the pattern, for example, the strips designated in FIG. 7 as Sl and S2, whereby, however, the method mentioned for residual class formation cannot be used.
In any case, during a simultaneous progress of the method, certain devices for the realization of the method of the invention must be multiply present. To the extent that this concerns devices for the controlling of the progress of the method, for the carrying out of transformations of the encoding and for the analysis, for this, a multi-processor system can be used.
In place of different decision feedback connections which, as needed, can be directed between random elements of the circuit arrangement of FIG. 7, two decision feedback connections are illustrated, in particular, from the output 13 of the decision device E to the input 9 of the first analysis 1 17~3778 device Al and from the output 19 of the encoder CD to the input 2 of t~e scanning device A in FIG. 7, They signal, for example, the completion of an operation which is to be carried out, for example, the analysis or, respectively, the encoding of a sub-region, and thus signal readiness for carrying out ~he next operation.
The decision feedback connection mentioned above, in particular, has the task of rejecting the determination of a sub-region which proceeded by means of the first analysis device Al if the analysis of the sub-region carried out in the second analysis device A2 does not result in a sufficient accuracy statement concerning the code to be used for the sub-region. In this case, the scanning dots contained in the rejected sub-region are assigned to the residual class of the analyzed strip and one proceeds as described above.
In contrast to the method set forth in the ~erman published application 25 16 332 for the differentiation of text and picture regions, scanning sharpness signals which suffice for the resolution of the printing raster structure of scanned pictures are not required, according to the present invention, for the analysis of the first kind (region limits analysis) or for specific methods set forth below for carrying out, again according to the present invention, the analysis of the second kind. It is, however, possible that methods according to the invention reauire the variable adjustment of specific parameters in dependence upon the printing raster freedom of pictures which are scanned, in particular, a special adjustment for such pi.ctures whereby the scanning sharpness does suffice for the resolution of the printing raster structure.

1 179~78 - In order to make an accommodation of method parameters to the printing raster structure unnecessary, entirely or to a large extent, it is advantageous in the case of the use of such analyzing methods which are not dependent upon a resolving of the print raster structure to subject the scanning signal to a pre-filtering ~efore execution of the limit and/or the region analysis which corresponds to a scanning with a sharpness which is reduced to such an extent that the raster structure is suppressed. Hereby, it suffices if the decreasing of the sharpness takes place only in a specific direction, for example, in the case of line-by-line scanning, in the line direction.
The method can also be used in the apparatus constructed in accordance with the present invention and schematically illustrated in FIG. 7. Devices for pre-filtering are not îllustrated in FIG. 7, nor are the devices for decreasing of the scanning sharpness corresponding to the German published application 25 16 332. Rather, in FIG. 7, they are considered as components of the analysis devices Al and/or A2. or, respectively, of the encoder CD.
A further development of the method of the present invention is characterized in that for a selection of scanning dots for the sub-region, from a scanning signal, the pattern brightness and/or the quality of gradients of the pattern brightness is determined in a transformed and quantized form, that a selection of the single-dimensional intervals or, respectively, two-dimensional intervals which arise by means of the quantization have associated thereto, in each case, an analysis result value per interval and that the frequency with ~ ~L79778 which an interval occurs within the sub~reg~on is transmitted to the analysis result value which is associated with this interval.
For the understanding of the following ex~lanations, it will first be explained what is to be understood by "pattern brightness" and "gradient of t~e pattern brightness".
Each dot within the gra~hic pattern can be stated by means of a pair of coordinates (x, y~ whereby the axes of the coordinates are defined corresponding to FIG, 1~ As pattern brightness, here a function h Cx,y) is designated which states the reflection factor or the light Permeability for light of a given spectral composition measured in the dot with the coordinates (XJY?-As gradient of the pattern brightness, a vector isdesignated having the two components:
gl (x,y~ h (x,y) g2 ~x,y) = ~y H (x,y~.
The quantity of the gradients of the Pattern brightness is desi~nated in the following as b (x,y), where b (x,y) is given by the following relationship:

b (x,y) = ~ g2 (x,y) + g2 (x.y).
From the scanning signal, for a sele.cted quantity of dots Pi of the sub-region, ~referably in the qub-region corresponding to FIG, 1, equidistantly arranged dots, a transformation h' Cxi,yi~;b' Cxi,Yi) of the value pair h (xi,yi~; b Cxi,yi~ is determined and subjected to a two-dimensional quantization in that h' (xi,yi~ is quantized at ~A

~ ~ 79778 quantization levels and b' Cxi,yi~ i5 quantized at NG
quan~ization levels. Hereby, each value pair h' (xi,yi);
b' (xi,yi~ is associated with ~ne of the t~tal NA:NG two-dimensional quantizati~n intervals.
For the clarification, in FIG. 4, the six two-dimensional quantization intervals are schematically illustrated which result in, for the quantization of the transformed pattern brightness, NS=3 was selected with the quantization thresholds 1 and 3 and when for the quantization of the transformed amount of the gradient of the pattern brightness ~G = 2 was selected with the quantization threshold 2. The six quantization intervals are numbered 1--6, Of these, the intervals 3--6 are opened on one of two sides.
In accordance with this, for example, the pair of valuesC2, 5: 1, 5~ are associated with the quantization -interval 2 and the value pair (O, 5; 3, 1) are associated with the quantization interval 4. In FIG. 4, 1 cm was selected as a unit.
A transformation of the value pair h (xi,yi);
b (xi,yi) consists, for example, of:
an integration of the pattern brightness over an environment of the dot (xi,yi)(such an integration proceeds unavoidably by means of the optical and electronic lack of sharpness of the scanning device, however, it can be intentionally intensified or changed for the filtering out of interferences within the pattern~;

~ 179778 a non-linear transformation o the ~îcture - brîghtness which is caused b~ the scanning device or is applied subsequently to the scanning signal;
a sLmplification of the com~utation of the gradient amount, for example, such that the di~ferential quotient of the ~rightness is replaced by the differential quotient of the transformed brightness corresponding to the equation b' (xi,yi) =

¦~h (Xi+l Yi) ~ h CXi-l~ Yi) 1 2 ~ ~ (xi Yi*l)-h (Xi-l~Yi) 1 2;and l Xi+l - Xi 1 ~ ~ Yi+l - Yi-l Another simplification of a computation of the gradient amount would consist in that the amount of the gradient is replaced by the sum of the amounts of its components or by the maximal value of the amounts of its components or another function of the amounts of its components which represents a measurement for the steepness of the brightness transitions at the selected scanning dots of the ~raphic pattern.

Further, and according to the invention, for n two-dimensional quantization intervals which represent a selection from the total of NA:NG intervals noted above, one counter each is present into which is read the number of the selected dots Pi of the sub-region which are associated with the interval in that the value pair h' (xi,yi); b' (xi,yi) falls into th.e interval in each case. The reading in can occur, for example, such that all counters are set to zero, that then the associated intervals are determined seauentially 1 ~1.797~8 for all dots Pi and thereby in each case the counter associated with the interval is incremented by one, to the extent that a counter is provided for this interval. After completion of read-in, the counts of the counter are ~ailable as analysis results.
A further advantageous form of this selection consists in that a transformation is undertaken by means of integration of the pattern brîghtness--as mentioned above--which simulates such a decreasing of the scanning sharpness that the raster structure of raster pictures is suppressed, The selection of this transformation can frequently be made uniformly for a specific kind of pattern, for example, a specific magazine.
It is advantageous to associate no counters to specific intervals when the evaluation of their frequency is not required for the code statement by the decision device E.
Whether this applies can be tested, where applicable, experimentally. To the extent that the result of this test turns out differently for different classes of patterns, it is advantageous to select the association of a counter to a specific pair of numbers in dependence upon the class to which the graphic pattern to be encoded belongs, for example, a specific magazine.
Correspondingly, it is advantageous to select the characterizing Eeatures of the transformation and of the quantization, in particular the limits of the quantization intervals as well as their number NA or, respectively, NG, based upon experimental investigations, for example, in accordance with the v:iewpoint that an optimum compromise is l 179778 found between the expense for the decision devices E and the reliab;lity and speed of t~e code statement. This selection can be made for different pattern classes in a different manner.
A particular ~orm of this selection consists in that either NA or NG i9 selected equal to`l. In this case, the determination of. h' (xi.,yi~ or, respectiveIy,.b.' (xi,yi) -becomes unnecessary because for the determination of the quantization interval associated with the pair of values, only one of the two val.ues must be quantized, The corresponding devices for the determination h' or, respectively,`b', can then, where applicable, be eliminated.
Another advantageous further development of the method of the present invention is characterized in that for a selection of scanning dots of the sub-region arranged line-wise and column-wise, by means of a first quantization at NA > 2 levels, quantized brightness values are determined which represent the pattern brightness values are determined which represent the pattern brightness in a quantized form in the scanning dots in each case, that from the quantized brightness values with the help of a second quantization at NL > 2 levels, run lengths are determined in quantized form, that in each case one analysis result value per interval is associated with a selection of the two-dimensional intervals which arise by means of the first and second quantizations, that the frequency with which an interval occurs within the sub-region is transmitted to the analysis result value which is associated with this interval. This further development will be explained more precisely in the following, with the use of FIG, 5 and FIG. 6.

I ~ 7977a FIG. 5 illustrates t~e scanning signals SlCt~ and S2Ct~ of the two first lines of a su~-region as weIl as, b~
means of a quantization, scanning values ~7hich are quantized at three levels with the thresholds `1,` 5 an* 2`, 5, which represent the pattern brightness in the scanning dots of these two lines. In FIG, 5-0`.5 cm was selected as a unit for representing Sl(t) and S2(t~, Further, in FIG, 5, run lengths Lll, L12,,,L21, L22...L31, L32...are illustrated. Hereby, for example, L23 signifies the third sequence of brightness values of the second quantization level which occurs within the sub-region.
FIG. 6 illustrates, in tabular form, the nine two-dimensional quantization levels numbered 1--9 which occur by means of the first quantization and the second quantization, whereby for the second quantization, three levels were assumed with the thresholds 1, 5 and 3, 5.
Further, in FIG. 6, for each quantization interval set forth in parentheses, the number of the run length is stated which drop out at the interval in each case when only the run lengths depicted in FIG. 5 are considered.
For illustrating the quantization intervals, 1 cm was selected as a unit for both coordinates.
The levels of the first quantization and the second quantization (NA or, respectively, NL) as well as the quantization thresholds in each case can be determined experimentally for a specific pattern class in view of random optimality criteria, just like the optimum selection of the quantization intervals with which an analysis value is associated.

l 179778 An advantageous modification in the senæ of a simplification of the method results in that, to an analysis result value, in place of the frequency of the two-dimensional quantization interval, the sum of the frequencies of several two-dimensional quantization întervals is transmitted, in particular, the sum of the fre~uencies of all quantization intervals which are associated with the same scanning value-quantization level.
For example, if one proceeds from the quantization intervals illustrated in FIG. 6, the sum of the frequencies of the intervals 1, 2 and 3_would be transmitted as a first analysis value, the sum of the frequencies of the intervals

4, 5 and 6 as a second analysis value> and the sum of the frequencies of the intervals 7, 8 and 9 would be transmitted as a third analysis value, from which the analysis values 6, 10 and 2 result.
_ To what extent the optimum number NA of the quantization levels of the first quantization depend upon the pattern class to be encoded can be shown with the following example.
If the sharpness of the scanning suffices for the resolution of the picture print raster, a two-level quantization (NA=2) of the scanning values suffices for the application of the method of the present invention. In the case that this prerequisite is not fulfilled, better results can be expected from a multi-level quantization (~ > 2), This further development of the invention is characterized in that an analysis result value is associated with a selection of two-dimensional spatial frequencies in each l~977~

case, that for e~ch of these frequencies, the amount of the spatial energy spectrum of the su~-region is determined, where applicable, in transformed form which is averaged over the environment of the frequency and that the amount is transmitted as the associated an~lysis result value~
A more precise explanation of this technique is given below with respect to FIGS, 8--10.
FIG. 8 represents a graphic pattern having a rectangular sub-region T. If, as in FIG. 8, ~e designates the coordinates of the two corner dots lying opposite one another with (xl,yl) and (x2,y2), then, in a known manner, the two-dimensional complex spectrum of the sub-region is calculated for a two-dimensional spatial frequency (x',y') which consists of two components, namely, the single-dimensional spatial frequencies x' and y~, according to the relationship H(x ,y ) = 3 12 h(x,y) ei27r (xx +YY') dx dy (1), y Yl x=xl where h (x,y) is the curve of the pattern brightness represented as a function of the coordinates.
By the amount of the energy spectrum of the sub-region, here a function E (x',y') of the spatial freauency is understood which, for its nart, is defined as a function of the complex frequency H (X I Y I ) through one of the following two equations E (x ,y ) = ¦H(XI YI)I (2) E (X Y ~ H(X ,Y~)I 2 + ¦H(X~,_Y~)I (3~
depending upon whether the frequency pairs (x',y') and (x', -y') i ~ 79778 are associated with a common two-dimensional spatial frequency (x',y'~ or not--whereby x' and y' are not negative.
The efficiency of the method of the present invention is not decisively dependent upon one of the other depiction of the ener~y spectrum is obtained corresponding to the one or the other formula.
The determination of the energy spectrum or, respectively, of t~ complex spatial spectrum is only possible in more or less approximated or transformed form. Suitable transformation methods are, for example, a~ the integral equation (1~ is replaced by a summation corresponding to the equation H(x',y') = ~ h(xi,yk)e i ~ (Xix + Yk Y ) (4) summed over a selection of dots ~xi,yl), for example, dots arranged regularly as in FIG, 2; and b) the amount obtained through formula 2 or, respectively, formula 3, is replaced by a monotonic non-decreasing function of the amount or by the sum of the amounts of the imaginary portion and the real portion of H(x',y') or by the maximal value of the two amounts.
In any case, according to the invention, the determination of the energy s~ectrum takes place for a selection of spatial two-dimensional frequencies which, similarlv to the pattern dots in FIG. 2~ can be arranged in regular frequency intervals within a preset fr~quency range.

~ ~797~8 It is, where applicabIe, advantageous to eaualize local fluctuations of the energy spectrum ~y means of averaging over the environment of the sPatial frequency in each case.
Such an averaging can be described by the formula:
00 ~,o FCx~,y`~ = J ~ ~TCu,v~ E(x'-u,y'-v~ du dv (5), wherein ~(u,v) signifies a weighting function which is select-able according to need and experience, E is the energy snectrum as descri~ed above and F Cx',y') is the energy spectrum averaged over the environment of the frequency (x',y'). Again, the integral can be replaced by a summation.
For example, the determination of F (-x`',y') for a selectlon of spatial frequencies Cxl-',-yl'),(`x2`', y~ ,etc takes place by averaging of, in each case, four neighboring values of the energy spectrum corresponding to the formula:

F (x',y') = 1/4 (E(x'- ~\x',y'- y'~+E(x'+ ~x',y'- ~ y')+
E (x'- ~ x',y'+ ~ y')+ E (x'+ ~ x',y'+ /\y')) (6) wherein x' and ~ are predetermined frequency intervals.
The values of the energy spectrum obtained, where applicable in averaged and transformed form, can now be turned over to a decision device which, from this, can derive a decision regarding the code which is favorable for the sub-region, because the energy spectra of ~icture regions and text regions, in general, differ significantly. This is illustrated in FIGS. 9--11.
FIG. 9 schematically represents the energy spectrum of a text region, while FIG, 10 schematically represents the energy spectrum of a picture regîon as a function of the l 1797~

spatial tw~-dimensional frequenc`~ x'~,`v~', In eac~ case~ those frequency ranges are hatched in which the avera~e ener~y spectrum exceeds a specific threshold. In FIG. 10, secondary spectra (Nl, N2...2 are identifiable which arise by means of the structure of the printing raster illustrated in FIG, 11 In FIG. 11, the locations of the black raster dots are identified by dots, and the white raster dots are identified with circles.
A further advantageous development of the invention provides a method for obtaining a code and a back-up statement out of a pregiven number of analysis values as result in the case of the use of the further developments of the invention which concern the advantageous analysis methods.
This metnod is characterized in that, for all except one analysis value, the relative portion of the analysis value is determin~d from the sum of all analysis values, that by means of quantization of such portions, a multi-dimensional interval is determined, that a memory is provided in which a memory region is assîgned to each possible interval, that each memory region contains a code statement and, where applicable, a back-up statement and that the code statement and, where applicable, the back-up statement or accuracy statement is taken from the memory region which is assigned to the interval which is determined.
This method will be explained in ~reater detail below with the use of equations, as well as with a numerical example.

1.~797~8 Here, it is assumed that N designates the number of the analysis values, `z(`I~, ZC2).~.ZCN~ designate the analysis values themselves. It is assumed that the analysis values are not negative.
~ ith this assumption, the reIative portion of the analysis value z(k) is provided ~y p (k) = z Ck~ / ~ z (i)-The end portion p (_)are not independent of oneanother because their sum is 1. Therefore, they are unam~iguously determined by a selection of (N-l) portions. Let the portion which is considered to be p(k'), where k' is a number selected from the region (l, N).
If now for all portions p (_~with the exception of p (k'), which did not need to be determined, one undertakes a quantization with in each case S (_)levels, then this signifies that one associates the analysis result represented by the N analysis values to one of a total of 1~ S(k) k = 1, k' (N~ dimensional quantization intervals. This will be explained below with the following example, as well as by means of FIG. 12.
Let N=3 and let the three analysis values be:
z (1) = 2, z (2~ = 3, z (4) = 5.

~ ~7~77~

Let k = 2 be selected, that is, the second analysis value is not considered in the selection of (N-1~= 2 analysis values. ~Jith this it is determined p (1~ = 2/10 = 0,2, and p c3~ = 5/10 = ~,5-Let the following quantizations be selected forthe analysis value p(l) and ~
for ~) the level number S(l) = 3 with the threshold 0.05 and 0.15; and for ~5~) the level number S(3) = 5 with the thresholds of 0.1, 0.2, 0.4, and 0`.7.
By means of this quantization, the 3 x 5 = 15 two-dimensional intervals illustrated in FIG. 12 are defined. The analysis result provided above as an example is associa~ed with the interval designated 14 in FIG. 12.
The scale of FIG. 12 was selected corresponding to 1 cm = 0.1.
-The association of a memory region with a specificmulti-dimensional interval can, for example, occur as follows.
The possible quantization intervals are successively numbered beginning with 1, for example, according to the pattern illustrated in FIG. 12. As soon as an interval is determined, the product of the interval number (C) and a pre-determined natural number B is determined.
The product C x B is used as a distance address measured in bits at the beginning of a memory field which is used as a table within a data memory. In this table, in B
consecutive bits in each case, the number is stated for the ~. 1797~

optimum code for the pertaining sub-reg;on.
For B = 1, by means of the content of the table, the decision is set ~etween a text code in the case of a specific table place content, for example, O, or a picture code in the case of another table place content, namely, l~
The content of the table is determined by statistical evaluation of a given quantity of representative patterns.
The characteristic number C is determined for one or several sub-regions of each pattern of the re~resentative quantity. From the characteristic number C, in addition, a memory region of the table is determined. This memory region is filled with the number of the optimum code for sub-region in each case, whereby it is presumed that this optimum code is known. After an evaluation of all graphic patterns of the representative quantity, it is checked, for each value of the characteristic number C which can appear in the class of graphic patterns to be encoded during evaluation of a sub-region, whether the pertaining table position has been filled, For checking of the pertaining table positions, an auxiliary memory is used in which a bit is associated with each value of the characteristic number C. Before the beginning of an evaluation of the graphic patterns of the representative quantity, the binary value O is assigned to all bit positions of the auxiliary memory field. During the evaluation of these graphic patterns, in each case when a value is determined for the characteristic number C, the binary value 1 is assigned to the bit position of the auxiliary memory field corresponding to this.

~ l7s7~a ~ fter the discovery of a non-filled table ~osition, the characteristic num~er C' which is most similar to this associated characteristic number C is determined. The pertaining table position is filled with a conten~ of the table position which is associated with the most simî-lar characteristic number C'.
The characteristic number C' which is most simîlar to a specific characteristic number C îs determined by means of a distance functîon in that all characteristic numbers to which the binary value 1 was associated in the auxiliary memory are compared with the characteristic number C. That number is selected as the most similar characteristic number C' for which the distance function Produces the smallest deviation between the characteristic number C and the most similar characterîstic number C'. As a distance function, for example, the summation of the absolute differences of the positions of the two characteristic numbers C, C' can be used, For the case that n > 1 characteristic numbers Cl'...Cn' having the same similarity, namely, with the same distance function, are found, that a characteristic one of the numbers Cl'...Cn' is selected which differs least by means of the algebraic difference from the associated characteristic number C.
According to another further development of the invention, ln a portîon of the memory field of the B bit which is associated with each characteristic number C, there is contained a second statement concerning the accuracy of the statement determined in the remaining positions of the memory field.

I. 1797~

According to anot~er further development of t~e invention, the selection is made from a num~er of alternative codes under consideration further evaluation composition associated thereto in each case.
The second statement mentioned above concerning the accuracy is determined according to another further development of the invention from the number and nature of the code statements found for the most similar n characteristic numbers Cl'...Cn', whereby the distance in each case to the characteristic number C is considered.
If during the setting-up of the table, a table position is recognized to be already filled, then the character-istic number C which has just been determined is marked with a number of the optimum code in an additional table. This additional table is checked after the setting-up of the table.
For all characteristic numbers C which appear in the additional table in multiple with different code numbers, an optimum code is determined by means of a compromise decision. This compromise decision can be made according to an exemplary embodiment of the invention by means of a majority decision, whereby that code is finally entered into the table which appears most frequently for the same characteristic number C
in the table and in the additional table. The compromise decision mentioned above can also be made advantageously in that one proceeds according to the principle of minimum damage, where-by that code is entered into the table which for a transmission, a reproduction or other process represents the optimum compromise both for the picture reglons and for the text regions, 1 ~797~8 Devices ~hich are suitable for the realization of the method of the present invention for o~taining a code statement and a ~ack-up accuracy statement are well known in the art. For example, for this purpose a programmed process computer is suitable which.at N inputs, the N anal~sis values are input in analog or digital form and which makes available at an output the code statement and the accuracy statement associated with the analysis result in the form of a digital signal. Programma~le process computers are obtainable on the market on a great nuM~er of different embodiments.
FIG. 13 illustrates a circuit arrangement for executing a portion of the method of the present invention whereby a scanning value coder 1~ is Provided with a si~nal input E for the inputting of scanning pulses generated by a scanning element, with a signal output iw for the out~utting of output signals representing recognized scanning values and a reset ouput CL for outputting reset signals, In addition, two interval decoders IWl and I~J2 are provided whid~are connected in cascade, em~odied in each case as threshold value circuits, and which are equipped in each case with a first decision output.N and a second decision output I and, in each case, a decision input EE. The decision input E~ of the first interval decoder IWl of the cascade is connected with the signal output iw, its first decision output N is connected with the decision input EE of the second interval decoder IW2 of the cascade, the first decision output N of the second interval decoder IW2 is connected with the signal input of an interval counter Z3 and in each case, the second decision output I of the first or, respectively, second interval decoder IWl or, respectively, IW2 is connected with the signal input of an I 17977~

interval counter Zl or, respectively~ Z2' The counting outputs of the interval counters Zl ? Z2 and Z3 are connect:ed with corresponding data inpùts of the calculating register R for the determination of the characteristic number C, One output of the calculating register R is connected for the transmission of the characteristic number C which has been determined to a data input,of a decider E~ Its signal output is connected to the control input of a code transfer switch U, The calculating register R has a further output Si which emits an accuracy signal, For resetting of the interval counters Zl~ Z2 and Z3, the reset output ZL of the scanning value decoder WD is connected with reset inputs of the counters Zl' Z2 and Z3.
Although I have described my invention by reference to particular illustrative embodiments thereof, many changes and modifications of the invention may become apParent to those skilled in the art without departing from the spirit and scope of the invention. I therefore intend to include within the patent warranted hereon all such changes and modification~ as may reasonably and properly be included within the scope of my contribution to the art,

Claims

I CLAIM:

1. A method for encoding electric signals obtained during the scanning of a graphic Pattern which is composed of a mixed content of text and pictures, comprising the steps of:
first, analyzing the electric signals in a first kind of analysis to determine at least one region in the graphic pattern;
second analyzing the electric signals at least once in a second kind of analysis to determine the region content;
evaluating the results of each of the region analysis and producing a respective code message; and selecting one of at least two predetermined codes, on the basis of the code message, and therewith encoding the content of the region.

2. The method of claim 1, wherein the first step of analyzing is further defined as:
analyzing the limits of a region with respect to white blocks.

3. The method of claim 1, wherein the first step of analyzing is further defined as:
analyzing the limits of a region with respect to column limits.

4. The method of claim 1, further comprising the step of:
associating a dot of a limiting white block with the closest region.

5. The method of claim 1, further comprising the step of:
encoding a limiting white block or part of such white block as an independent region.

6. The method of claim 5, wherein the step of encoding is further defined as:
encoding with a text code.

7. The method of claim 1, wherein the step of encoding is further defined as:
for a region which is bounded on a minimum number of sides including two sides which are opposite one another bounded by white blocks and/or column limits whose spacing does not exceed a predetermined maximum value, encoding with a text code.

8. The method of claim 7, comprising the step of:
setting the maximum number in dependence upon the type of pattern to be encoded.

9. The method of claim 7, comprising the step of:
setting the minimum number in dependence upon the type of pattern to be encoded.

10. The method of claim 7, comprising the step of:
setting the maximum and minimum numbers in dependence upon the type of pattern to be encoded.

11. The method of claim 7, wherein;
the first and second analysis steps are performed sequentially, 12. The method of claim 7, wherein:
the first and second analysis steps are performed simultaneously.

13. The method of claim 7, wherein for several regions, the step of encoding is performed, at any time after the analysis results are obtained, sequentially for the several regions.

14. The method of claim 7, wherein:
for several regions, the step of encoding is performed, at any time after the analysis results are obtained, simultaneously for the several regions.

15. The method for encoding electric signals obtained during the scanning of a graphic pattern of mixed content of text and pictures, comprising the steps of:

first, analyzing the electric signals in a first kind of analysis to determine the boundaries of at least one region in the graphic pattern;
second, analyzing the electric signals at least once in a second kind of analysis to determine the region content and producing a respective code message;
encoding the region content into code signals in accordance with a predetermined code;
storing the code signals; and selecting a code to be utilized as the encoded signals from the stored codes.

16. A method for encoding electric signals obtained during the scanning of a graphic pattern which is composed of a mixed content of text and pictures, comprising the steps of:
dividing the graphic pattern into sections, and, for each section, analyzing the electric signals in a first kind of analysis to determine at least one region in the graphic pattern;
analyzing the electric signals at least once in a second kind of analysis to determine the region content;
evaluating the results of each of the region analysis and producing a respective code message; and selecting one of at least two predetermined codes, on the basis of the code message, and therewith encoding the content of the region.

17. A method of encoding electric signals obtained during the scanning of a graphic pattern composed of a mixture of text and pictures, comprising the steps of:
analyzing the electric signals in an analysis of a first kind to determine the boundries of at least one region in the graphic pattern;
analyzing the electric signals at least once for each region in an analysis of a second kind to produce for each region a code message of region content and an accuracy message;
selecting one of at least two predetermined codes by evaluating the code messages and accuracy messages to determine the code most like that representing region content;
and encoding the electric signals in accordance with the selected code, 18. The method of claim 17, wherein the step of encoding is further defined as:
encoding a region which has at least one boundary within the graphic pattern together with the adjacent region when the accuracy message of such section is evaluated as insufficient, 19. The method of claim 17, comprising the further step of filtering the electric signals before analyzing the same to decrease sharpness so as to suppress print raster structure only in the horizontal direction, 20, The method of claim 17, and further comprising the steps of:
for selecting scanning dots of a region from the scanning signals;
quantizing the pattern brightness or the magnitude of gradient of pattern brightness;
selecting at least a one-dimensional interval which arises by the quantization and obtaining an analysis result per interval;
determining the frequency of interval appearance within the pattern; and transmitting the frequency to the respective analysis result associated with the respective interval, 21. The method of claim 20, wherein the graphic pattern belongs to a certain class of graphic patterns, and wherein the selection of scanning dots and/or intervals is further defined as:
selecting in accordance with and in dependence upon the class of the graphic pattern.

22. The method of claim 20, for selecting scanning dots of a region arranged by columns and by lines, comprising the particular steps of:
quantizing the brightness values in A first quantization step to at least two quantization levels to represent pattern brightness;
quantizing the quantized brightness values in a second quantization step to at least two quantization levels to determine run length;
associating an analysis result value per interval with a selection of two-dimensional intervals which occur by the first and second quantization steps; and then transmitting the interval appearance frequency to the analysis result associated with the interval.

23, The method of claim 22, comprising the further step of:
summing the frequencies of interval occurrence of a plurality of two-dimensional quantization levels and transmitting the same to the analysis result, 24. The method of claim 22, and comprising the steps of:
associating an analysis result value with a selection of two-dimensional spatial frequencies;
determining the amount of the spatial energy spectrum of a region;
transforming such amount and averaging the same over the environment of the frequency; and transmitting the averaged transformed amount to the relative analysis result value.

25. A method of encoding electric signals obtained during the scanning of a graphic pattern composed of a mixture of text and pictures, comprising the steps of:
analyzing the electric signals in an analysis of a first kind to determine the boundries of at least one region in the graphic pattern;
analyzing the electric signals at least once for each region in an analysis of a second kind to produce for each region a code message of region content and an accuracy message;
selecting one of at least two predetermined codes by evaluating the code messages and accuracy messages to determine the code most like that representing region content;
encoding the electric signals in accordance with the selected code;
with the exception of one analysis value. determining a relative portion of each analysis value with respect to the sum of all analysis values;
quantizing the relative portions to determine a multi-dimensional interval;
storing the respective multi-dimensional intervals in respective associate memory regions along with a respective code message and a respective accuracy message; and reading the associated code and accuracy messages associated with a respective interval.

26. The method of claim 25, and further defined by the steps of:
forming, after determination of an interval, a product of an interval number (C-I) associated with the interval; and determining a predetermined natural number B, where C is a characteristic number.

27. The method of claim 26, and further defined by the step of:
for the expression (C x B) for a predetermined function f(C), forming a table in a memory field within a data memory by storing the function as a distance address, measured in bits, at the beginning of the memory field so that in the table, in B consecutive bits, the number of an optimum code for a region is stored.

28. The method of claim 27, and particularly characterized by the step of:
for B=1, selecting between a text code or a picture code in response to a table position content of "0" or "1", respectively.

25. The method of claim 27, further defined by the step of:
statistically evaluating a plurality of representative patterns to obtain the content of the table, 30. The method of claim 29, further defined by the steps of:
selecting a characteristic number C for each region T of each pattern M to determine a memory region of the table; and storing a known optimum code in the memory region.

31. The method of claim 30, and further defined by the step of:
checking whether the pertaining table location has been filled for each value of the characteristic number C after evaluation of the representative quantities of all of the graphic patterns.

32. The method of claim 31, further defined by the step of:
associating a bit with each value of the characteristic number C in an auxiliary memory during the step of checking the table locations.

33. The method of claim 32, and further defined by the steps of:
assigning the binary value "0" to all bit locations of the auxiliary memory before evaluating the graphic patterns M
for the representative quantity; and when a value has been determined for the characteristic number C, assigning the binary value "1" to the pertaining bit location.

34. The method of claim 33, and further defined by the steps of:
upon discovery of an unfilled table location, determining a characteristic number C' which is most similar to the characteristic number C; and storing the similar characteristic number C' in the pertaining table location.

35. The method of claim 34, and further defined by the steps of:
determining the similar characteristic number C' by comparing the characteristic number C to which the binary value "1" is associated in the auxiliary memory with all characteristic numbers; and selecting as the most similar characteristic number C' that number for which a distance function produces a minimum deviation between the characteristic number C and the most similar characteristic number C'.

36. The method of claim 35, wherein the distance function is defined as:
summing the absolute differences of the locations of the two characteristic numbers C, C'.

37. The method of claim 35, and further defined by the step of:
for the case that n > 1 characteristic numbers C1',.,Cn' of the same similarity are found with the same distance function, selecting that one of the numbers C1',..Cn' which differs least from the associated characteristic number C by the algebraic difference.

38. The method of claim 37 ? comprising the further step of:
storing an accuracy message in memory locations of a memory field in which other locations of the memory field store the B bit associated with each characteristic number C.

39. The method of claim 38, comprising the step of:
determining the second message from the number and kind of codes for the most similar n characteristic numbers Cl'...Cn' by considering the distance with respect to the characteristic number C.

40. The method of claim 34, and further defined by the steps of:
identifying table locations which are filled;
marking the just-determined characteristic number C with the number of the optimum code in an additional table;
checking the additional table after completion of setting-up of the first-mentioned table; and for all characteristic number C which appear in the additional table, in multiple, with different code numbers, determining an optimum code by selecting a compromise of the codes.

41. The method of claim 40, wherein the step of selecting is further defined as:
selecting and storing into the table that code which, for the same characteristic number C, appears most frequently in the table and in the additional table.

42. The method of claim 40, wherein the step of selecting is further defined as:
selecting and storing into the table that code which represents the optimum compromise for transmission, reproduction or other processes both for picture regions and text regions on the basis of the code which will cause minimum damage.

43. A circuit arrangement for encoding electric scanning pulse signals obtained from scanning a graphic pattern having a mixed content of text and pictures, comprising:
a scanning value decoder including a signal input for receiving the scanning pulse signals, a signal output and a reset output, and operable to produce output signals at said signal output representing recognized scanning values and reset signals at said reset output representing end of scan;
first and second interval decoders connected in series, each of said interval decoders including an input, a threshold value circuit having a respective threshold connected to said input, and first and second decision outputs, said first decision output of said first interval decoder connected to said input of said second interval decoder, each of said interval decoders operable to produce output signals on said decision outputs representing the magnitude of their input signals in relation to their threshold values;
a three-stage interval counter, each stage including an input connected to a predetermined decision output, a reset input connected to said reset output of said scanning decoder, and an output;
a calculating register for calculating a characteristic number, including data inputs connected to said counter outputs, and an output for the characteristic number;
a code selection switch for selecting a code; and a decision circuit connected between said output of said calculating register and said code selection switch for controlling code selection in accordance with the characteristic number.

44. The circuit arrangement of claim 43, wherein said calculating register includes a further output and is operable to produce an accuracy message at said further output.

45. A circuit arrangement for encoding electrical scanning signals obtained by scanning the graphic pattern having a mixed text and picture contact, comprising:
a scanning device for producing scanning signals in digital form;
a first buffer connected to said scanning device for storing the digital signals;
a first analysis device connected to said first buffer and operable in response to buffer content to determine the limits of regions within the graphic pattern;
a second analysis device connected to said first analysis device and to said first buffer for analyzing the region content within the limits of the region determined by said first analysis device;

a decision device connected to said second analysis device and operable in response to the analysis of region content to determine which of at least two predetermined codes is to be used for encoding the determined region; and an encoder connected to said first buffer and to said decision device for receiving the digital signals from said first buffer and encoding the same in accordance with the decision of said decision device, 46. The circuit arrangement of claim 451 and further comprising:
a feedback connection between said encoder and said scanning device, said encoder further operable to produce a feedback signal to inform said scanning device of completion of encoding and to scan another section of the graphic pattern;
and a second buffer connected to said encoder for receiving the encoded signals.

47. The circuit arrangement of claim 45, and further comprising:
a connection between said first analysis device and said encoder to inform the encoder of the limits of the scanned region.

48. The circuit arrangement according to claim 45, and further comprising:
a feedback connection between said decision device and said first analysis device, said decision device operable to produce a rejection signal to said first analysis device over said feedback connection, 49. The circuit arrangement of claim 45, and further comprising:
a counter preset to zero connected to said second analysis device and operable for in each case a selected one-dimensional or two-dimensional quantization interval, to increase its count by one when a dot of the graphic pattern is associated with the interval by said second analysis device.