CN1298600A

CN1298600A - Densitometry method

Info

Publication number: CN1298600A
Application number: CN 99805587
Authority: CN
Inventors: 迈克尔·约翰·豪厄尔
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-04-28
Filing date: 1999-04-23
Publication date: 2001-06-06
Also published as: WO1999056462A1; EP1076992A1; JP2002513252A; AU3619499A; GB9808968D0

Abstract

A method of performing densitometry on photographic films and papers or the like, in which a processed film control strip (1) is digitally scanned (3) and analysed to produce a set of constant exposure information tables (5). The information contained in these tables is cross referenced (9) with appropriate transmission/reflection density values (7) and statistical techniques (11) are applied to the data to give a mapping of the transmission/reflection density values (7) to the constant exposure information (5).

Description

Densitometry method

The present invention relates to a kind of Densitometry method and device thereof.

The process of spectrodensitometry is exactly to measure the optical transmission property and/or the optical reflection characteristic of the optical characteristics, particularly material of material.Light densitometry is special but be not optical density (OD) (absorptivity or reflectivity) and/or the colour content that only is only applicable to measure through the photographed image of overexposure and processing.

Aspect processing film and printing paper, quality control is normally based on control tool or the reference material of using pre-exposure, control tool or reference material to this pre-exposure are handled and/or are printed, then, measure optical density (OD) (absorptivity or reflectivity) and/or colour content by means of the spectrodensitometry instrument.

Control tool or reference material can be known, as: control strip, step wedge, printer test article or monitor.Reference material or the sample (providing with that handled and/or printed sample) that (under controlled conditions of exposure) made under the pre-exposure condition is provided in film manufacturer, perhaps can utilize a kind of known controlled exposure instrument, as actinometer, make reference film.Reference material contains the constant exposure zone that is referred to as " (steps) step by step " usually.

Opacimeter (perhaps being used for measuring the equipment of optical density) is a kind of measuring instrument, it provides the controlled irradiation to film or printing paper sample, and be provided with one or more photoelectric cells, the illumination that sees through the light of sample or reflected by sample is mapped on one or more photoelectric cells, so that photoelectric cell produces the output signal of being decided by light.Opacimeter is measured the output signal of photoelectric cell, and output signal is converted to the common metric standard of representing with " ODU ".Usually, opacimeter can use the light intensity of optical filtering at the different-waveband test samples of visible spectrum, with the intensity properties of explanation sample look composition (for example red, green and blue, perhaps darkviolet and yellow).With regard to measuring a given sample, the output of opacimeter (representing with ODU) can be calculated (process controlcomputation) by manually writing down and being used for processing controls, perhaps the output of opacimeter (for example can be passed through modulator-demodulator) directly or indirectly and be connected with the processing controls computer.In addition, opacimeter also can be configured to carry out some inner basic operations and result's storage.Therefore, opacimeter can be to directly measuring through the light of object or by the light of object reflection accurately.In order to ensure obtaining high accuracy and reproducible result, this quasi-instrument needs the very high optics of service quality.

In addition, complicated scientific instrument, for example opacimeter must cost an arm and a leg, and does not reach the market scale that reduces product price by extensive competition and large-scale production.

First aspect of the present invention provides a kind of Densitometry method, and its step comprises: a file or image scanner are provided; The pre-exposure control tool handled or reference material are replaced traditional file or image and put into scanner; Handle scanner and produce a digital output signal, this digital output signal is represented the optical density of control tool of being put into or reference material and/or the measurement result of colour content; And send the digital output signal of scanner to digital computing system, this digital computing system is analyzed the output signal of scanner according to program, so that aspect IMAGE REPRODUCTION, for example, handling film or printing paper, quality control is carried out in aspects such as copy chart, x-ray film.

File or image scanner are used for the image of file (for example chart and/or the text file on film or the printing paper) is scanned and make its digitlization, this is a kind of personal computer (PC) equipment of more and more popularizing, and its present price and the association of practicality advantage huge market, competition and large-scale production.File or image scanner provide light source controlled irradiation and with the output signal of computer compatibility, this output code name representative color and density (absorption of light and reflection).Use a file or image scanner, add a digital computing system (for example personal computer) of being furnished with proper procedure, just can carry out the mensuration of optical density, thereby film or printing paper can handled, particularly no matter commerce or professional treatment film or printing paper (are visible scene or target, still carry out quality control in process x-ray film, or other image) and in the process of the IMAGE REPRODUCTION of other form.

Second aspect of the present invention provided a kind of spectrodensitometry equipment, and this equipment comprises the combination of a file or an image scanner and a digital computing system; Described file or image scanner can accept to replace the pre-exposure control tool or the reference material of traditional file or image, and control tool or reference material scanned produce a digital output signal, this output signal is represented the optical density of control tool of being accepted or reference material and/or the measurement result of colour content; Described digital computing system is connected with file scanner, be used for receiving the digital output signal of scanner, in described digital computing system, program, be used for the output signal of scanner is analyzed, so that aspect IMAGE REPRODUCTION, for example carry out quality control at aspects such as handling film or printing paper, copy chart, x-ray film.

To embodiments of the invention be described by example below.

Prepare commercially availabie image, film or a hard copy (paper seal file (paper-printed documents)) scanner, this is a kind of device that can make image digitization check, handle, transmit or store with the input computer.Scanner contains light source, optical sensor and realizes the necessary suitable control circuit of digitlization.The output of scanner links to each other with personal computer (independently digital computer).For the handled control tool of scanner, reference film, sample film or other material, computer receives and handles the output signal of scanner according to program, this output signal is similar to the optical density (OD) of transmitted ray or reflection ray specific wavelength or by special optical filtering.In video secondary industry field, optical filtering can be a kind of in industrial numerous filter that define or the density optical filtering, for example " Status A " and " Status M " filter.

Prepare the calibration bag (calibrationpack) and the densitometric numerical tabular thereof of a treated film or printing paper control strip (strips).Ideally but be not necessarily, have a control strip in this calibration bag at least in the photography optical filtering of 3 kinds of forms each, and each control strip all exposes with discrete intensity number (number of discrete levels) (being generally 21 or higher).

Fig. 1 is the flow chart of calibration scan instrument.For the calibration scan instrument, from the calibration bag, take out a control strip and put into scanner.Control strip can be made by negative film 1, positive photoresist film 1A or printing paper 1B.After control strip scanned, scanning result 3 stored with standard digital form such as bitmap (bit-map).For every kind of color, the image of being stored should contain 8 at least, and this provides the range of luminance values of 0-255 for every kind of color.Then, the image of being stored is carried out numerical analysis, with the zone of definite constant exposure (" step by step "), and produce three tables 5, each table is corresponding to a kind of color in redness, green and the blueness.

Then, for each color, the information in the above-mentioned table is carried out cross bearing (cross reference) 9 with the information that is included in suitable/known transmission/reflection density value table 7.The purpose of this measure is, compares between the given known brightness value in colour brightness value that scanner obtained and transmission/reflection density value table 7.

Only provide in given brightness values under the situation of single colour brightness value, with this density value map to the colour brightness value of being measured.Under the situation of having used the several samples with equal densities, corresponding colour brightness will be the mean value of the colour brightness measured.

Utilize statistical method, for example glug youth or three sample function interpolation methods (Legrangian orCubic Spline Interpolation) are set up the table 11 of a cover based on above-mentioned map, respectively set up a table corresponding to redness, green and blueness.For positive control strip 1A or printing paper control strip 1B, also can enough similar approach carry out said process.

This method is at the photography optical filtering form of control strip, provides a kind of map or correspondence between the colour brightness value that given OD value and scanning obtain.This method should be used the OD value table of each optical filtering form in sample and the three kinds photography optical filtering form.Map or correspondence are used for the calibration scan instrument, can accurately represent transmission/reflection density so that scanner is the same with opacimeter.

Use scanner, digital computer and known densitometric transmission/reflected value, just can carry out the quality control that will detect, and needn't use opacimeter to carry out routine measurement picture developing and printing etc.Therefore, the present invention makes the calibration of scanner that accurate and cheap quality control can be provided.

By obtaining the OD value of control strip and reference bar, the present invention can be as a kind of quality control apparatus of routine, and its step is as follows:

Reference bar is scanned, and Image storage is got up.Analyze image and produce 3 tables, these 3 tables provide redness, green and blue colour brightness value (0-255 or higher).Select the redness, green or the blue colour brightness value that match with the optical density look-up table according to optical filtering.The calibration chart that use is set up above carries out with the same statistical analysis in front, is determined the OD value of reference bar by the colour brightness value of scanning.In the same way, control strip is scanned and obtains its density value.

The density value of existing known road reference bar and control strip, this just can carry out the quality control that video is handled, as the OD value of reading reference bar and control strip on opacimeter.

The routine that the present invention can also be used for photographic material compares.A sample of material of handling with known optical density characteristic is scanned, as described above, obtain OD value from scanner.Under similarity condition, as handling known materials unknown sample is handled, unknown sample is scanned, and determine its optical density.According to the contrast of the OD value of two kinds of samples, just can determine the difference between the photographic parameter, for example speed, contrast or any this type of calculating, this is just as determining OD value.

In another example, the present invention can be used as a kind of device of definite printer printing quality, as described above, by scanning a test photograph, determines the optical density of test photograph.By the OD value of contrast test photograph, just can determine the phase tablet quality of back.

Usually, for the known input of a scanner, for example control tool or reference material just can be determined the information of relevant processing controls state by computer.Under the situation of knowing the processing controls state, just can take adequate measures, for example come correcting action according to optimal parameter.

Under the situation of the characteristic of the input material in not knowing scanner, the film of a unknown performance for example, but since know input material the state of a control (can obtain like that) of process of process according to earlier paragraphs is described, thereby can determine the information of relevant input material.

Can know augmented performance by various measurements (alone or any appropriate combination), for example, the scanner that service precision is higher, the more rational algorithm of use are estimated optical density (OD), are used known standard input to make the response characteristicization of hardware and system and use other this class to improve one's methods.

Be positioned at versicolor brightness of spectral region or wave-length coverage because the present invention is suitable for analyzing, therefore, can imagine that the present invention can also be used as spectrometer.

In the improvement that is applied to spectroscopy equipment, can comprise the step that light source or photoelectric cell are filtered.

Can also imagine that digital scanner and calculation element can be used in combination with the used single discrete cell of the present invention.

Embodiment described above can make various improvement and variation under the situation that does not depart from the scope of the invention.Though specific descriptions of the present invention are that the quality control of handling with film is that example is carried out,, the present invention also is applicable to the IMAGE REPRODUCTION of other form, for example chart duplicates, and promptly specialty, commercial and industrial are printed chart, file, other image on X-ray film or the printing paper, or the like.

Claims

1, a kind of Densitometry method comprises the following steps: to provide a file or image scanner; The pre-exposure control tool handled or reference material are replaced traditional file or image and put into scanner; Handle scanner and produce a digital output signal, this digital output signal is represented the optical density of control tool of being put into or reference material and/or the measurement result of colour content; And send the digital output signal of scanner to digital computing system, this digital computing system is analyzed the output signal of scanner according to program, so that aspect IMAGE REPRODUCTION, for example, handling film or printing paper, quality control is carried out in aspects such as copy chart, x-ray film.

2, a kind of spectrodensitometry equipment, this equipment comprises the combination of a file or an image scanner and a digital computing system; Described file or image scanner can accept to replace the pre-exposure control tool or the reference material of traditional file or image, and control tool or reference material scanned produce a digital output signal, this output signal is represented the optical density of control tool of being accepted or reference material and/or the measurement result of colour content; Described digital computing system is connected with file scanner, be used for receiving the digital output signal of scanner, in described digital computing system, program, be used for the output signal of scanner is analyzed, so that aspect IMAGE REPRODUCTION, for example carry out quality control at aspects such as handling film or printing paper, copy chart, x-ray film.