CN106407979B - Method and device for correcting bill characters - Google Patents
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- CN106407979B CN106407979B CN201610942281.1A CN201610942281A CN106407979B CN 106407979 B CN106407979 B CN 106407979B CN 201610942281 A CN201610942281 A CN 201610942281A CN 106407979 B CN106407979 B CN 106407979B
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- 238000000034 method Methods 0.000 title claims abstract description 36
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- G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
- G06V30/00—Character recognition; Recognising digital ink; Document-oriented image-based pattern recognition
- G06V30/10—Character recognition
- G06V30/14—Image acquisition
- G06V30/146—Aligning or centring of the image pick-up or image-field
- G06V30/1475—Inclination or skew detection or correction of characters or of image to be recognised
- G06V30/1478—Inclination or skew detection or correction of characters or of image to be recognised of characters or characters lines
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- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T3/00—Geometric image transformations in the plane of the image
- G06T3/60—Rotation of whole images or parts thereof
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Abstract
The invention belongs to the technical field of bill image recognition, and provides a method and a device for bill character correction, which aim to solve the problems that when the existing character inclination correction method is used for integrally correcting inclined characters under the condition that the bill characters are inclined to different degrees and the inclination degree of each character is different, on one hand, some characters are still inclined seriously, and on the other hand, the whole bill image is corrected, so that the algorithm time complexity is increased, and the algorithm efficiency is reduced. Compared with the prior art that character inclination is solved by correcting the whole bill image, the method and the device have the advantages that the rectangular area in the range of the preset buffer area outside the minimum external rectangle of a single character is corrected, so that the inclination angle of each character is controlled in the range without influencing character recognition, the whole bill image is prevented from being corrected, the algorithm time complexity is reduced, and the recognition efficiency is improved.
Description
Technical Field
The invention belongs to the technical field of bill image recognition, and particularly relates to a bill character correction method and a bill character correction device.
Background
The characters on the bill surface are an important mark and a reliable way for recording and analyzing information. The valuable bills, especially the bank bills, are a widely used settlement method, the automatic Recognition of the face characters of the valuable bills is particularly important, and the wide application of the OCR (Optical Character Recognition) processing technology as a research hotspot in the field of Character Recognition and document analysis in the Character Recognition of the valuable bills is also proved.
Character recognition of value document generally includes image preprocessing, tilt correction, character positioning and character recognition.
The whole inclination of the whole line of characters can occur in the collection of the bill images, the whole line is on the same straight line after the inclination, the inclination angles of all the characters are the same, and the character inclination problem can be solved by correcting the whole bill image by utilizing the characteristics.
the inventor finds that the characters of the bill are inclined to different degrees due to movement, extrusion and the like in the process of acquiring the image of the bill, and the inclination degree of each character is different.
Disclosure of Invention
The embodiment of the invention provides a bill character correction method, aiming at solving the problems that when the existing character inclination correction method is used for integrally correcting inclined characters under the condition that the bill characters are inclined to different degrees and the inclination degree of each character is different, on one hand, some characters are still inclined seriously, and on the other hand, the whole bill image is corrected, so that the algorithm time complexity is increased and the algorithm efficiency is reduced.
in a first aspect of the embodiments of the present invention, a method for correcting a ticket character is provided, where the method includes:
detecting a single character in the face image;
determining a rectangular area in a preset buffer area range outside the minimum external rectangle of the single character;
calculating the inclination angle of the rectangular area in the range of the preset buffer area outside the minimum external rectangle relative to the symmetry axis of the bill or calculating the inclination angle of the rectangular area in the range of the preset buffer area outside the minimum external rectangle relative to a straight line which is intersected with a preset point on the symmetry axis, wherein the inclination angle of the straight line relative to the symmetry axis is in a preset range;
and correcting the rectangular area within the range of the preset buffer area outside the minimum external rectangle according to the inclination angle.
In a second aspect of the embodiments of the present invention, there is provided an apparatus for ticket character correction, the apparatus including:
The detection module is used for detecting a single character in the ticket image;
The determining module is used for determining a rectangular area in a preset buffer area range outside the minimum external rectangle of the single character;
The calculation module is used for calculating the inclination angle of the rectangular area in the range of the preset buffer area outside the minimum external rectangle relative to the symmetry axis of the bill or calculating the inclination angle of the rectangular area in the range of the preset buffer area outside the minimum external rectangle relative to a straight line intersected with a preset point on the symmetry axis, wherein the inclination angle of the straight line relative to the symmetry axis is in a preset range;
And the correcting module is used for correcting the rectangular area within the range of the preset buffer area outside the minimum external rectangle according to the inclination angle.
Compared with the prior art, the embodiment of the invention has the following beneficial effects: the method for correcting the bill is provided, and single characters in the bill surface are detected; determining a rectangular area in a preset buffer area range outside the minimum external rectangle of the single character; calculating the inclination angle of the rectangular area in the range of the preset buffer area outside the minimum external rectangle relative to the symmetry axis of the bill or calculating the inclination angle of the rectangular area in the range of the preset buffer area outside the minimum external rectangle relative to a straight line which is intersected with a preset point on the symmetry axis, wherein the inclination angle of the straight line relative to the symmetry axis is in a preset range; and correcting the rectangular area within the range of the preset buffer area outside the minimum external rectangle according to the inclination angle. Compared with the prior art that the character inclination is solved by correcting the whole bill image, the technical scheme can independently correct the inclination of each character, so that the inclination angle of each character relative to the bill is controlled within the range without influencing character recognition, the automatic character recognition efficiency can be improved, the whole bill image is prevented from being corrected in a rotating mode, and the time complexity of an algorithm is reduced.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.
FIG. 1-1 is a flow chart of a method for ticket character correction according to an embodiment of the present invention;
FIGS. 1-2 are schematic diagrams of a minimum bounding rectangle of a single character according to an embodiment of the present invention;
FIGS. 1-3 are schematic diagrams of rectangular areas within a predetermined buffer area outside a minimum bounding rectangle for a single character according to an embodiment of the present invention;
fig. 1 to 4 are schematic diagrams for calculating an inclination angle of a rectangular region within a preset buffer area outside a minimum circumscribed rectangle with respect to a symmetry axis of a bill and calculating an inclination angle of a rectangular region within a preset buffer area outside the minimum circumscribed rectangle with respect to a straight line intersecting a preset point on the symmetry axis, where an included angle between the straight line and the symmetry axis is within a preset range, according to an embodiment of the present invention;
FIG. 2 is a schematic structural diagram of a bill character correction apparatus according to a second embodiment of the present invention;
FIG. 3 is a schematic structural diagram of a device for ticket character correction according to a third embodiment of the present invention;
FIG. 4-1 is a schematic structural diagram of a device for ticket character correction according to a fourth embodiment of the present invention;
fig. 4-2 is a schematic structural diagram of a device for ticket character correction according to a fourth embodiment of the present invention.
Detailed Description
in order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments.
In the following description, for purposes of explanation and not limitation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known devices and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.
the first embodiment is as follows:
The bill includes various securities and certificates such as stocks, treasury bonds, corporate bonds, invoices, bills of lading, and the like, and the shape thereof is mostly a symmetrical shape, especially a rectangle.
The method aims to effectively solve the problems that when the existing character inclination correction method is used for integrally correcting inclined characters under the condition that the bill characters are inclined to different degrees and the inclination degree of each character is different, on one hand, some characters are still seriously inclined, and on the other hand, the whole bill image is corrected, so that the algorithm time complexity is increased and the algorithm efficiency is reduced. The method for correcting the bill characters provided by the embodiment comprises the following steps: detecting a single character in the face image; determining a rectangular area in a preset buffer area range outside the minimum external rectangle of the single character; calculating the inclination angle of the rectangular area in the range of the preset buffer area outside the minimum external rectangle relative to the symmetry axis of the bill or calculating the inclination angle of the rectangular area in the range of the preset buffer area outside the minimum external rectangle relative to a straight line which is intersected with a preset point on the symmetry axis, wherein the inclination angle of the straight line relative to the symmetry axis is in a preset range; and correcting the rectangular area within the range of the preset buffer area outside the minimum external rectangle according to the inclination angle.
fig. 1-1 shows a flowchart of a method for correcting a ticket character according to an embodiment of the present invention, and for convenience of description, fig. 1-1 shows only a part related to this embodiment, and the process thereof is detailed as follows:
In step S101, a single character in the ticket image is detected.
Preferably, the single character in the ticket face can be a printed or handwritten form of characters, numbers and various fonts used by countries or regions of the world or nations, such as Arabic numerals, Chinese Pinyin letters, Chinese characters, big and small English letters and the like.
preferably, single character detection is carried out after binarization is carried out on the bill surface according to the characteristics of the characters in the bill surface, such as the characteristics that the brightness values of the character areas and background pixels are obviously different or the character outlines or the continuity of a string of a plurality of characters are formed.
Preferably, the detection of the single character can be carried out in a preset area on the bill surface according to the position of the character in each bill, the detection range of the method is fixed, the target performance is high, and the detection efficiency can be improved.
It should be noted that, in the present embodiment, the detection of a single character in the ticket face indicates that the processing object is directed to the single character, and lays a foundation for other subsequent technical features, which is also a core point of the present application, and this is different from the processing of the whole ticket image in the prior art, and the processing efficiency is improved.
In step S102, a rectangular area outside the minimum bounding rectangle of the single character within a preset buffer area is determined.
two different definitions are possible for the minimum bounding rectangle, the first being the minimum area rectangle and the second being the maximum extent of several two-dimensional shapes (e.g., points, lines, polygons) in two-dimensional coordinates, i.e., the rectangle bounded by the maximum abscissa, minimum abscissa, maximum ordinate, minimum ordinate in the vertices of a given two-dimensional shape.
the minimum bounding rectangle in this embodiment refers to a minimum area bounding rectangle, and fig. 1-2 show schematic diagrams of the minimum bounding rectangle of a single character provided in this embodiment. For ease of understanding, the secondary rectangular coordinate system xoy is established with the letter "O" being framed by a first defined rectangle aligned with the rectangle labeled with the short side length dimension 9.35 and the long side length dimension 14.76, i.e., a first defined rectangle, and a second defined rectangle aligned with the rectangle labeled with the short side length dimension 9.49 and the long side length dimension 14.73, i.e., a second defined rectangle, the length dimensions illustrated in the figures also being understood to mean that the first defined rectangle, i.e., the minimum area circumscribing the rectangle, is smaller in area than the second defined rectangle. If viewed in fig. 1-2, the rectangle aligned with the short side length dimension 9.35 and the long side length dimension 14.76 is the smallest circumscribed rectangle referred to herein.
The rectangle in the preset buffer area range outside the minimum external rectangle refers to a rectangle in the preset buffer area range outside the closed area of the minimum external rectangle side line, and the area of the rectangle is larger than that of the minimum external rectangle. Fig. 1 to 3 are schematic diagrams of rectangular regions within a preset buffer area outside a minimum circumscribed rectangle of a single character provided in the present embodiment, and for convenience of understanding, a secondary rectangular coordinate system xoy is established, where the rectangle abcd is the minimum circumscribed rectangle of the single character, and a rectangle a 'b' c'd' is formed by using a preset distance as a buffer area outside the rectangular abcd closed area with reference to each side or a preset section of each side of the rectangle abcd, as in fig. 1 to 3, a rectangle a1b1c1d1 is an example of a rectangle within the preset buffer area outside the minimum circumscribed rectangle, and in fig. 1 to 3, a shaded portion in fig. 1 to 3, where a side of a1b1c1d1 is outside the rectangle abcd and inside the rectangle a 'b' c'd', is just an example, and the shaded portion may also be an irregular shape.
It should be noted that, in the embodiment, the range of the preset buffer area outside the minimum circumscribed rectangle may be an empirical value range obtained after a large sample is passed.
Preferably, in the embodiment of the present invention, the determining of the rectangular area in the range of the preset buffer area outside the minimum circumscribed rectangle of the single character may be implemented by the following steps S1021 and S1022:
And S1021, searching a rectangular area in a preset buffer area range outside the minimum external rectangle of the single character.
It should be noted that, the number of rectangular regions in the range of the preset buffer area outside the minimum external rectangle of a single character is infinite, and as long as a reasonable number (for example, 1) of rectangular regions in the range of the preset buffer area outside the minimum external rectangle of each character is found, the rectangular regions in the range of the preset buffer area outside the minimum external rectangle of the next character are found.
In step S1022, the rectangular area outside the minimum circumscribed rectangle erroneously detected as a single character within the preset buffer area is excluded.
preferably, the rectangular area within the range of the preset buffer area outside the minimum circumscribed rectangle misdetected as a single character is a rectangular area within the range of the preset buffer area outside the minimum circumscribed rectangle misdetected as a single character in the ticket face, and partial images of the ticket face are misdetected as a single character in the process of detecting the single character in the ticket face.
preferably, the rectangular area within the preset buffer area range outside the minimum circumscribed rectangle excluding the false detection as a single character may be a rectangular area within the preset buffer area range outside the minimum circumscribed rectangle excluding the false detection as a single character according to at least one of preset ranges of the height, the width, and the ratio of the height to the width of the character; according to the preset range of the center of the rectangular region in the preset buffer area range outside the minimum external rectangle of the single character, eliminating the rectangular region in the preset buffer area range outside the minimum external rectangle which is falsely detected as the single character; and according to the condition that the rectangular area in the range of the preset buffer area outside the minimum external rectangle wrongly detected as the single character and the rectangular areas in the range of the preset buffer area outside the minimum external rectangle of other single characters form an overlapping area, excluding at least one of the rectangular areas in the range of the preset buffer area outside the minimum external rectangle wrongly detected as the single character.
Because the height and width of the character, especially the print character and the ratio of the height and width of the character have the established writing specification, and the character in the bill has a stricter regulation, the height and width of the character and the ratio of the height and width are all in a certain range, and the range of the preset height, width and ratio of the height and width is obtained by calculating a large sample according to at least one of the preset ranges of the height, width and ratio of the height and width of the character, the rectangular area in the preset buffer area outside the minimum external rectangle which is falsely detected as a single character is excluded.
Because the position of a character, particularly a print character, in a bill is relatively in a fixed range, the centers of the characters are gathered in the relatively fixed range, so that the gathering area of the center of a rectangular area in the range of a preset buffer area outside the minimum external rectangle of a single character also has the relatively fixed range, the range can be obtained by adopting a clustering method through large sample calculation, and then whether the rectangular area in the range of the preset buffer area outside the minimum external rectangle of the currently searched single character is in the range is judged, if the rectangular area is in the range, the character is in the searched rectangle, and the character is not excluded, otherwise, the character is excluded. The characters in the bill are more strictly regulated, for example, even though the characters are handwritten, the bill is generally handled in a bank, and specified squares or transverse lines are used for guiding and standardizing writing, so that according to the preset range of the center of the rectangular region in the range of the preset buffer area outside the minimum external rectangle of the single character, which is detected by mistake, can be excluded.
And if the situation that the rectangular area in the range of the preset buffer area outside the minimum external rectangle which is falsely detected as the single character and the rectangular area in the range of the preset buffer area outside the minimum external rectangle of other single characters form an overlapping area is met, excluding the rectangular area in the range of the preset buffer area outside the minimum external rectangle which is falsely detected as the single character.
preferably, the condition is the shape of the overlapping area and/or the measured size and/or area of the overlapping area, that is, a rectangular area within a preset buffer area outside the minimum circumscribed rectangle erroneously detected as a single character can be excluded according to the shape of the overlapping area and/or the measured size and/or area of the overlapping area.
It should be noted that the exclusion is also an empirical value obtained by calculation using a large sample, when the size and/or area of the bottom overlap region is small or large.
it should be further noted that, because there may be image areas similar to characters in the bill, but the algorithm applied in step S101 or considering that many reasons such as detecting characters in step S101 are not to be omitted as much as possible, it is not determined that the image areas are not characters, and a rectangular area in the preset buffer area range outside the minimum circumscribed rectangle that is erroneously detected as a single character is excluded, so that the rectangular area in the preset buffer area range outside the minimum circumscribed rectangle of the found single character is reduced, the efficiency of subsequent processing is improved, the interferences such as stains and non-characters are excluded, and the precision of subsequent processing is improved.
in step S103, an inclination angle of a rectangular region within the range of the preset buffer area outside the minimum circumscribed rectangle with respect to a bill symmetry axis is calculated, or an inclination angle of a rectangular region within the range of the preset buffer area outside the minimum circumscribed rectangle with respect to a straight line intersecting a preset point on the symmetry axis is calculated, and an included angle between the straight line and the symmetry axis is within a preset range.
And calculating the inclination angle of the rectangular area in the range of the preset buffer area outside the minimum external rectangle relative to the symmetry axis of the bill.
note that the symmetry axis of the bill can be equivalent to all lines parallel to the symmetry axis of the bill, including the long and short edges of the bill. In this embodiment, the inclination angle of one straight line with respect to the other is in the range of [0, π/2 ].
Fig. 1 to 4 are schematic diagrams for calculating the inclination angle of the rectangular region within the range of the preset buffer area outside the minimum circumscribed rectangle with respect to the symmetry axis of the bill, provided in the present embodiment, for the convenience of understanding and explaining the principle, an auxiliary rectangular coordinate system xoy is established, and a somewhat exaggerated drawing is adopted, and in fig. 1 to 4, the rectangle MNPQ is assumed to be the bill, and the rectangle a1b1c1d1 is the rectangle within the range of the preset buffer area outside the finally determined minimum circumscribed rectangle, but in practice, the rectangle within the range of the preset buffer area outside the minimum circumscribed rectangle is not so large with respect to the bill in general. HH' is an axis of symmetry of the document, and for convenience is drawn in fig. 1-4 as a straight line segment, which is equivalent to a line parallel to all of it, including the long and short edges of the document. In fig. 1-4, the rectangular area a1b1c1d1 within the preset buffer area outside the minimum circumscribed rectangle is calculated to be the inclination angle of the parallel line KK 'of the symmetry axis of the calculated rectangle a1b1c1d1 with respect to the bill symmetry axis HH'. For convenience, KK' is drawn as a straight line segment in fig. 1-4, which is equivalent to a straight line parallel to all its lines, including the long and short sides of a1b1c1d 1. In fig. 1-4, the size of the inclination angle is the included angle between HH 'and KK', and this included angle can be equal to the complement angle thereof, so the complement angle of the included angle between HH 'and KK' can also be obtained as the inclination angle of the rectangular area in the range of the preset buffer area outside the minimum circumscribed rectangle relative to the symmetry axis of the bill.
and calculating the inclination angle of the rectangular area in the range of the preset buffer area outside the minimum external rectangle relative to a straight line which is intersected with a preset point on a bill symmetry axis, wherein the inclination angle of the straight line relative to the symmetry axis is in a preset range.
fig. 1 to 4 show the calculated inclination angles of the rectangular regions within the range of the preset buffer area outside the minimum circumscribed rectangle provided in this embodiment relative to the straight line intersecting the preset point on the symmetry axis, where the inclination angle of the straight line relative to the symmetry axis is within a preset range, which can be obtained by a large sample calculation. The straight line crossing the preset point S on the symmetry axis HH 'of the bill is JJ', the included angle α between the straight line JJ 'and the symmetry axis HH' is within a preset range, and the value of the angle β or the complement thereof is an example of calculating the inclination angle of the rectangular region a1b1c1d1 within the range of the preset buffer area outside the minimum circumscribed rectangle with respect to the straight line JJ 'crossing the preset point S on the symmetry axis HH'.
In step S104, a rectangular area within a preset buffer area range outside the minimum circumscribed rectangle is corrected according to the inclination angle.
Preferably, in the embodiment of the present invention, the correcting the rectangular area within the range of the preset buffer area outside the minimum circumscribed rectangle according to the inclination angle may be implemented by the following steps S1041 and S1042:
Step S1041, comparing the inclination angle with a preset angle range.
Preferably, the predetermined angular range may be divided into a plurality of mutually consecutive intervals, for example three mutually consecutive intervals.
As shown in FIGS. 1-4, the tilt angle β is compared to determine whether it is within a predetermined range of angles, such as the open range (5 π/12,19 π/40), the closed range [0,5 π/12], and the closed range [19 π/40, π/2 ].
step S1042, if the tilt angle belongs to a preset angle range, clockwise or counterclockwise rotating the rectangular region within the preset buffer area range outside the minimum circumscribed rectangle.
As shown in fig. 1-4, if the tilt angle β is within the open interval (5 π/12,19 π/40), the rectangular area a1b1c1d1 within the predetermined buffer area outside the minimum circumscribed rectangle is rotated counterclockwise.
and the inclination angle beta is in the range of [0,5 pi/12 ] or [19 pi/40, pi/2 ], the rectangular area a1b1c1d1 is not rotated.
The rectangular area a1b1c1d1 with the rotation angle beta within the range of [19 pi/40, pi/2 ] is not rotated, because the character is not inclined relative to the bill or the inclination angle is within the preset range at the moment, the subsequent character recognition is not influenced, the inclination correction is not needed, the number of rectangles needing to be corrected is reduced, the algorithm time complexity is reduced, and the operation efficiency is improved.
The rectangular area a1b1c1d1 with the rotation angle beta within the range of [0,5 pi/12 ] is not rotated, because characters are probably not in the a1b1c1d1 at this time, caution is needed, rotation is not carried out, and therefore the number of rectangles needing to be corrected is reduced, the algorithm time complexity is reduced, and the operation efficiency is improved.
It should be noted that the above specific angle interval is only an example, and in practice, the interval can be obtained by calculation with a large sample. And correcting the characters one by one, and then, rotating the corresponding images which are detected as single characters, wherein the rotation is performed until the characters are not inclined relative to the bill or the inclination angle is within a preset range, subsequent character recognition and the like are not influenced, and in some cases, clockwise rotation can also be performed.
The embodiment of the invention provides a bill correction method, which is used for independently performing inclination correction on each character, so that the inclination angle of each character relative to a bill can be controlled within a range which does not influence character recognition.
Example two:
fig. 2 is a schematic structural diagram of a ticket character correction device according to a second embodiment of the present invention. For convenience of explanation, fig. 2 shows only portions related to the embodiment of the present invention. The device for ticket character correction illustrated in fig. 2 comprises a detection module 201, a determination module 202, a calculation module 203 and a correction module 204, wherein:
The detection module 201 is used for detecting a single character in the ticket image.
Preferably, the single character in the ticket face can be a print or a handwriting of characters, numbers and various fonts used by countries or regions of the world or nations, such as Arabic numerals, Chinese Pinyin letters, Chinese characters, big and small English letters and the like.
Preferably, single character detection is carried out after binarization is carried out on the bill surface according to the characteristics of the characters in the bill surface, such as the characteristics that the brightness values of the character areas and background pixels are obviously different or the character outlines or the continuity of a string of a plurality of characters are formed.
Preferably, the detection of the single character can be carried out in a preset area on the bill surface according to the position of the character in each bill, the detection range of the method is fixed, the target performance is high, and the detection efficiency can be improved.
It should be noted that, in the present embodiment, the detection of a single character in the ticket face indicates that the processing object is directed to the single character, and lays a foundation for other subsequent technical features, which is also a core point of the present application, and this is different from the processing of the whole ticket image in the prior art, and the processing efficiency is improved.
And the determining module 202 is configured to determine a rectangular area within a preset buffer area outside the minimum circumscribed rectangle of the single character.
Two different definitions are possible for the minimum bounding rectangle, the first being the minimum area rectangle and the second being the maximum extent of several two-dimensional shapes (e.g., points, lines, polygons) in two-dimensional coordinates, i.e., the rectangle bounded by the maximum abscissa, minimum abscissa, maximum ordinate, minimum ordinate in the vertices of a given two-dimensional shape.
The present embodiment is the same as the first embodiment, and thus the description will be given with reference to fig. 1 to 2 and fig. 1 to 3 in the first embodiment.
The minimum circumscribed rectangle in this embodiment refers to a minimum area circumscribed rectangle, and the area thereof is larger than the minimum circumscribed area rectangle. Fig. 1-2 show a schematic diagram of a minimum bounding rectangle of a single character provided in the present embodiment, and for the convenience of understanding, a secondary rectangular coordinate system xoy is established, where the letter O is framed by rectangles aligned with and labeled with a short side length dimension of 9.35 and a long side length dimension of 14.76, i.e., a first defined rectangle, and rectangles aligned with and labeled with a short side length dimension of 9.49 and a long side length dimension of 14.73, i.e., a second defined rectangle, and the first defined rectangle, i.e., the minimum area bounding rectangle, is smaller in area than the second defined rectangle, as also understood from the length dimensions illustrated in the figures. If viewed in fig. 1-2, the rectangle aligned with the short side length dimension 9.35 and the long side length dimension 14.76 is the smallest circumscribed rectangle referred to herein.
A rectangle in the range of the preset buffer area outside the minimum circumscribed rectangle refers to a rectangle in the range of the preset buffer area outside the minimum circumscribed rectangle side-line closed area, a schematic diagram of a rectangle area in the range of the preset buffer area outside the minimum circumscribed rectangle side-line closed area of a single character provided in the present embodiment is shown in fig. 1 to 3, and for the convenience of understanding, an auxiliary rectangular coordinate system xoy is established, in which a rectangle abcd is the minimum circumscribed rectangle of the single character, a rectangle a 'b' c'd' is formed outside the rectangle abcd closed area with a preset distance as a buffer area with reference to each side or a preset section of each side of the rectangle abcd, as an example of a rectangle a1b1c1d1 in fig. 1 to 3 being a rectangle in the range of the preset buffer area outside the minimum circumscribed rectangle, sides of a1b1c1d1 are outside the rectangle abcd and sides of a 'b' c'd' are in the shaded portions in fig. 1 to 3, the shaded portions in fig. 1-3 are only an example, and the shaded portions may be an irregular shape.
It should be noted that, in the embodiment, the range of the preset buffer area outside the minimum circumscribed rectangle may be an empirical value range obtained after a large sample is passed.
It should be noted that, because there may be image areas similar to characters in the bill, but the algorithm applied in step S101 or considering that many reasons such as detecting characters in step S101 need not omit characters as much as possible and the like, it is not determined that the characters are not characters, a rectangular area in the preset buffer area range outside the minimum circumscribed rectangle that is erroneously detected as a single character is excluded, a rectangular area in the preset buffer area range outside the minimum circumscribed rectangle of the found single character is reduced, the efficiency of subsequent processing is improved, the interferences such as stains and non-characters are excluded, and the precision of subsequent processing is improved.
And the calculating module 203 is used for calculating the inclination angle of the rectangular area in the range of the preset buffer area outside the minimum external rectangle relative to the symmetry axis of the bill or calculating the inclination angle of the rectangular area in the range of the preset buffer area outside the minimum external rectangle relative to a straight line intersected with a preset point on the symmetry axis, wherein the inclination angle of the straight line relative to the symmetry axis is in a preset range.
And calculating the inclination angle of the rectangular area in the range of the preset buffer area outside the minimum external rectangle relative to the symmetry axis of the bill.
Note that the symmetry axis of the bill can be equivalent to all lines parallel to the symmetry axis of the bill, including the long and short edges of the bill. In this embodiment, the angle of inclination of one straight line with respect to the other is in the range of [0, π/2 ].
This embodiment is the same as the first embodiment, and thus the description will be given with reference to fig. 1 to 4 in the first embodiment.
Fig. 1 to 4 are schematic diagrams for calculating the inclination angle of the rectangular region within the range of the preset buffer area outside the minimum circumscribed rectangle with respect to the symmetry axis of the bill, provided in the present embodiment, for the convenience of understanding and explaining the principle, an auxiliary rectangular coordinate system xoy is established, and a somewhat exaggerated drawing is adopted, and in fig. 1 to 4, the rectangle MNPQ is assumed to be the bill, and the rectangle a1b1c1d1 is the rectangle within the range of the preset buffer area outside the finally determined minimum circumscribed rectangle, but in practice, the rectangle within the range of the preset buffer area outside the minimum circumscribed rectangle is not so large with respect to the bill in general. HH' is an axis of symmetry of the document, and for convenience is drawn in fig. 1-4 as a straight line segment, which is equivalent to a line parallel to all of it, including the long and short edges of the document. In fig. 1-4, the rectangular area a1b1c1d1 within the preset buffer area outside the minimum circumscribed rectangle is calculated to be the inclination angle of the parallel line KK 'of the symmetry axis of the calculated rectangle a1b1c1d1 with respect to the bill symmetry axis HH'. For convenience, KK' is drawn as a straight line segment in fig. 1-4, which is equivalent to a straight line parallel to all its lines, including the long and short sides of a1b1c1d 1. In fig. 1-4, the size of the inclination angle is the included angle between HH 'and KK', and this included angle can be equal to the complement angle thereof, so the complement angle of the included angle between HH 'and KK' can also be obtained as the inclination angle of the rectangular area in the range of the preset buffer area outside the minimum circumscribed rectangle relative to the symmetry axis of the bill.
And calculating the inclination angle of the rectangular area in the range of the preset buffer area outside the minimum external rectangle relative to a straight line which is intersected with a preset point on a bill symmetry axis, wherein the inclination angle of the straight line relative to the symmetry axis is in a preset range.
Fig. 1 to 4 show the calculated inclination angles of the rectangular regions within the range of the preset buffer area outside the minimum circumscribed rectangle provided in this embodiment relative to the straight line intersecting the preset point on the symmetry axis, where the inclination angle of the straight line relative to the symmetry axis is within a preset range, which can be obtained by a large sample calculation. The straight line crossing the preset point S on the symmetry axis HH 'of the bill is JJ', the included angle α between the straight line JJ 'and the symmetry axis HH' is within a preset range, and the value of the angle β or the complement thereof is an example of calculating the inclination angle of the rectangular region a1b1c1d1 within the range of the preset buffer area outside the minimum circumscribed rectangle with respect to the straight line JJ 'crossing the preset point S on the symmetry axis HH'.
And the correcting module 204 is configured to correct a rectangular area within a preset buffer area range outside the minimum circumscribed rectangle according to the inclination angle.
It should be noted that, if the inclination angle is within the preset angle interval, the rectangular area within the preset buffer area range outside the minimum circumscribed rectangle is corrected, and in practice, the interval can be calculated and obtained through a large sample. And correcting the characters one by one, and correcting corresponding images which are detected as single characters so that the characters are not inclined relative to the bill or the inclination angle is in a preset range, and subsequent character recognition is not influenced.
It should be noted that, in the implementation of the currency-oriented recognition device according to the second embodiment of the present invention shown in fig. 2, for convenience and simplicity of description, the above-mentioned division of the functional units and modules is merely used as an example, and in practical applications, the above-mentioned function distribution may be completed by different functional modules according to needs, such as configuration requirements of corresponding hardware or convenience of implementation of software, that is, the internal structure of the device for correcting the bill characters is divided into different functional modules, so as to complete all or part of the above-mentioned functions. In practical applications, the corresponding functional modules in this embodiment may be implemented by corresponding hardware, or may be implemented by corresponding hardware executing corresponding software, for example, the detecting module may be hardware having a function of detecting a single character in a ticket, such as a detector, or a general processor or other hardware device capable of executing a corresponding computer program to perform the detecting function. In addition, specific names of the functional units and modules are only for convenience of distinguishing from each other, and are not used for limiting the protection scope of the present application. (the principles described above can be applied to various embodiments provided in this specification).
Example three:
The determining module 202 shown in fig. 2 may include a searching unit 301 and an excluding unit 302, as shown in fig. 3, which is a schematic structural diagram of a device for ticket character correction according to a third embodiment of the present invention. Wherein:
The searching unit 301 is configured to search a rectangular area within a preset buffer area range outside the minimum circumscribed rectangle of the single character.
it should be noted that, the number of rectangular regions in the range of the preset buffer area outside the minimum external rectangle of a single character is infinite, and as long as a reasonable number (for example, 1) of rectangular regions in the range of the preset buffer area outside the minimum external rectangle of each character is found, the rectangular regions in the range of the preset buffer area outside the minimum external rectangle of the next character are found.
An excluding unit 302 is configured to exclude a rectangular region within a preset buffer area outside the minimum circumscribed rectangle erroneously detected as a single character.
Preferably, the rectangular area within the range of the preset buffer area outside the minimum circumscribed rectangle misdetected as a single character is a rectangular area within the range of the preset buffer area outside the minimum circumscribed rectangle misdetected as a single character in the ticket face, and partial images of the ticket face are misdetected as a single character in the process of detecting the single character in the ticket face.
Preferably, the excluding unit 302 includes: the first exclusion subunit is used for excluding a rectangular area which is in a preset buffer area range outside the minimum external rectangle and is falsely detected as a single character according to at least one of the preset ranges of the height, the width and the ratio of the height to the width of the character; the second exclusion subunit is used for excluding the rectangular area which is erroneously detected as the single character and is within the range of the preset buffer area outside the minimum circumscribed rectangle according to the preset range of the center of the rectangular area within the range of the preset buffer area outside the minimum circumscribed rectangle of the single character; and the third exclusion subunit is used for excluding at least one of the rectangular areas in the preset buffer area range outside the minimum external rectangle falsely detected as the single character according to the condition that the rectangular area in the preset buffer area range outside the minimum external rectangle of the single character and the rectangular area in the preset buffer area range outside the minimum external rectangle of other single characters form an overlapping area.
Because the height and width of the character, especially the print character and the ratio of the height and width of the character have the established writing specification, and the character in the bill has a strict regulation, the height and width of the character and the ratio of the height and width are all in a certain range, and the range of the preset ratio of the height and width of the character is obtained by calculating a large sample according to at least one of the range of the preset ratio of the height, width, height and width of the character, so that the first removing unit can be used for removing the rectangular area which is detected as the rectangular area in the range of the preset buffer area outside the minimum external rectangle of a single character by mistake.
Because the position of a character, particularly a print character, in a bill is relatively in a fixed range, the centers of the characters are gathered in the relatively fixed range, so that the gathering area of the center of a rectangular area in the range of a preset buffer area outside the minimum external rectangle of a single character also has the relatively fixed range, the range can be obtained by adopting a clustering method through large sample calculation, and then whether the rectangular area in the range of the preset buffer area outside the minimum external rectangle of the currently searched single character is in the range is judged, if the rectangular area is in the range, the character is in the searched rectangle, and the character is not excluded, otherwise, the character is excluded. The characters in the bill are more strictly regulated, for example, even though the characters are handwritten, the bill is generally written in a bank transaction bill by a specified square grid or transverse line for guiding and standardizing, so that according to the preset range of the center of the rectangular area in the range of the preset buffer area outside the minimum external rectangle of the single character, the rectangular area in the range of the preset buffer area outside the minimum external rectangle which is detected as the single character by mistake can be eliminated by the second eliminating unit.
If a rectangular region in the range of the preset buffer area outside the minimum circumscribed rectangle erroneously detected as a single character and a rectangular region in the range of the preset buffer area outside the minimum circumscribed rectangle of other single characters form an overlapping region, a third excluding unit may exclude the rectangular region in the range of the preset buffer area outside the minimum circumscribed rectangle erroneously detected as a single character.
Preferably, the condition is the shape of the overlapping area and/or the measured size and/or area of the overlapping area, that is, a rectangular area within a preset buffer area outside the minimum circumscribed rectangle erroneously detected as a single character can be excluded according to the shape of the overlapping area and/or the measured size and/or area of the overlapping area.
It should be noted that the exclusion is also an empirical value obtained by calculation using a large sample, when the size and/or area of the bottom overlap region is small or large.
It should be further noted that, because there may be image areas similar to characters in the bill, but the algorithm applied in the detection module 201 or many reasons such as that characters are not missed as much as possible when the detection module 201 detects characters are considered, it is not determined that the characters are not characters, a rectangular area in the preset buffer area range outside the minimum circumscribed rectangle that is erroneously detected as a single character is excluded, a rectangular area in the preset buffer area range outside the minimum circumscribed rectangle that is found for a single character is reduced, the efficiency of subsequent processing is improved, the interferences such as stains and non-characters are excluded, and the precision of subsequent processing is improved.
Example four:
The correction module 204 shown in fig. 2 or fig. 3 may include a comparison unit 401 and a rotation unit 402, as shown in fig. 4-1 or fig. 4-2, which is a schematic structural diagram of a device for ticket character correction provided by a fourth embodiment of the present invention. Wherein:
this embodiment is the same as the first embodiment, and thus the description will be given with reference to fig. 1 to 4 in the first embodiment.
A comparing unit 401, configured to compare the inclination angle with a preset angle range.
Preferably, the predetermined angular range may be divided into a plurality of mutually consecutive intervals, for example three mutually consecutive intervals.
as shown in FIGS. 1-4, the tilt angle β is compared to determine whether it is within a predetermined range of angles, such as the open range (5 π/12,19 π/40), the closed range [0,5 π/12], and the closed range [19 π/40, π/2 ].
A rotating unit 402, configured to rotate the rectangular region within the preset buffer area range outside the minimum circumscribed rectangle clockwise or counterclockwise if the inclination angle belongs to the preset angle range.
as shown in fig. 1-4, if the tilt angle β is within the open interval (5 π/12,19 π/40), the rectangular area a1b1c1d1 within the predetermined buffer area outside the minimum circumscribed rectangle is rotated counterclockwise.
And the inclination angle beta is in the range of [0,5 pi/12 ] or [19 pi/40, pi/2 ], the rectangular area a1b1c1d1 is not rotated.
The rectangular area a1b1c1d1 with the rotation angle beta within the range of [19 pi/40, pi/2 ] is not rotated, because the character is not inclined relative to the bill or the inclination angle is within the preset range at the moment, the subsequent character recognition is not influenced, the inclination correction is not needed, the number of rectangles needing to be corrected is reduced, the algorithm time complexity is reduced, and the operation efficiency is improved.
The rectangular area a1b1c1d1 with the rotation angle beta within the range of [0,5 pi/12 ] is not rotated, because characters are probably not in the a1b1c1d1 at this time, caution is needed, rotation is not carried out, and therefore the number of rectangles needing to be corrected is reduced, the algorithm time complexity is reduced, and the operation efficiency is improved.
it should be noted that the above specific angle interval is only an example, and in practice, the interval can be obtained by calculation with a large sample. And correcting the characters one by one, and then, rotating the corresponding images which are detected as single characters, wherein the rotation is performed until the characters are not inclined relative to the bill or the inclination angle is within a preset range, subsequent character recognition and the like are not influenced, and in some cases, clockwise rotation can also be performed.
It should be noted that, because the contents of information interaction, execution process, and the like among the modules/units in the second, third, and fourth embodiments and the overall contents of the embodiments are based on the same concept, the technical effects brought by the embodiments are the same as those of the embodiments of the methods of the present invention, and specific contents may refer to the description of the embodiments of the methods of the present invention, and are not described herein again.
It should be noted that, in all embodiments of the present invention, terms such as "first", "second", "third", and the like are referred to herein only for convenience of description and reference, and do not necessarily mean that there are corresponding first and second exclusion units in a specific implementation manner of the present invention.
It will be further understood by those skilled in the art that all or part of the steps in the method for implementing the above embodiments may be implemented by relevant hardware instructed by a program stored in a computer-readable storage medium, such as ROM/RAM, magnetic disk, optical disk, etc.
The foregoing is a more detailed description of the principles and embodiments of the present invention, taken in conjunction with the accompanying preferred embodiments, which are not to be taken in a limiting sense, but are for the purpose of illustrating the invention; also, it will be apparent to those skilled in the art that several equivalent substitutions or obvious modifications can be made without departing from the spirit of the invention, and all changes in performance or use that are equivalent are intended to fall within the scope of the invention as defined in the appended claims.
Claims (8)
1. A method of ticket character correction, the method comprising:
Detecting a single character in the face image;
Determining a rectangular area within a preset buffer area range outside the minimum circumscribed rectangle of the single character, including: searching a rectangular area in a preset buffer area range outside the minimum external rectangle of the single character; eliminating a rectangular area in a preset buffer area range outside the minimum external rectangle which is falsely detected as a single character; the rectangle in the range of the preset buffer zone outside the minimum external rectangle refers to a rectangle in the range of the preset buffer zone outside the closed area of the side line of the minimum external rectangle, and the area of the rectangle in the range of the preset buffer zone outside the minimum external rectangle is larger than that of the rectangle with the minimum external area;
calculating the inclination angle of the rectangular area in the range of the preset buffer area outside the minimum external rectangle relative to the symmetry axis of the bill or calculating the inclination angle of the rectangular area in the range of the preset buffer area outside the minimum external rectangle relative to a straight line which is intersected with a preset point on the symmetry axis, wherein the inclination angle of the straight line relative to the symmetry axis is in a preset range;
And correcting the rectangular area within the range of the preset buffer zone outside the minimum external rectangle according to the inclination angle of the rectangular area within the range of the preset buffer zone outside the minimum external rectangle relative to the symmetry axis of the bill or the inclination angle of the rectangular area within the range of the preset buffer zone outside the minimum external rectangle relative to the straight line intersecting with the preset point on the symmetry axis.
2. the method of claim 1, wherein said excluding rectangular areas outside of a minimum bounding rectangle for false detection as a single character within a predetermined buffer comprises:
According to at least one of the preset ranges of the height and the width of the character and the ratio of the height to the width, excluding a rectangular area which is detected as a single character by mistake and is in the range of a preset buffer area outside a minimum external rectangle;
According to the preset range of the center of the rectangular region in the preset buffer area range outside the minimum external rectangle of the single character, eliminating the rectangular region in the preset buffer area range outside the minimum external rectangle which is falsely detected as the single character;
And according to the condition that the rectangular area in the range of the preset buffer area outside the minimum external rectangle wrongly detected as the single character and the rectangular areas in the range of the preset buffer area outside the minimum external rectangle of other single characters form an overlapping area, excluding at least one of the rectangular areas in the range of the preset buffer area outside the minimum external rectangle wrongly detected as the single character.
3. the method of claim 2, wherein the condition is a shape of the overlapping region and/or a measured size and/or area of the overlapping region.
4. The method according to any one of claims 1 to 3, wherein the correcting the rectangular area within the range of the preset buffer area outside the minimum bounding rectangle according to the inclination angle comprises:
comparing the inclination angle with a preset angle range;
And if the inclination angle belongs to a preset angle range, clockwise or anticlockwise rotating the rectangular area in the range of the preset buffer area outside the minimum external rectangle.
5. An apparatus for ticket character correction, the apparatus comprising:
The detection module is used for detecting a single character in the ticket image;
The determining module is used for determining a rectangular area in a preset buffer area range outside the minimum circumscribed rectangle of the single character, and comprises: the searching unit is used for searching a rectangular area in the range of a preset buffer area outside the minimum external rectangle of the single character; the excluding unit is used for excluding a rectangular area which is in the range of a preset buffer area outside the minimum external rectangle and is wrongly detected as a single character; the rectangle in the range of the preset buffer zone outside the minimum external rectangle refers to a rectangle in the range of the preset buffer zone outside the closed area of the side line of the minimum external rectangle, and the area of the rectangle in the range of the preset buffer zone outside the minimum external rectangle is larger than that of the rectangle with the minimum external area;
The calculation module is used for calculating the inclination angle of the rectangular area in the range of the preset buffer area outside the minimum external rectangle relative to the symmetry axis of the bill or calculating the inclination angle of the rectangular area in the range of the preset buffer area outside the minimum external rectangle relative to a straight line intersected with a preset point on the symmetry axis, wherein the inclination angle of the straight line relative to the symmetry axis is in a preset range;
And the correcting module is used for correcting the rectangular area in the range of the preset buffer area outside the minimum external rectangle according to the inclination angle of the rectangular area in the range of the preset buffer area outside the minimum external rectangle relative to the symmetric axis of the bill or the inclination angle of the rectangular area in the range of the preset buffer area outside the minimum external rectangle relative to the straight line intersected with the preset point on the symmetric axis.
6. The apparatus of claim 5, wherein the exclusion unit comprises:
The first exclusion subunit is used for excluding a rectangular area which is in a preset buffer area range outside the minimum external rectangle and is falsely detected as a single character according to at least one of the preset ranges of the height, the width and the ratio of the height to the width of the character;
The second exclusion subunit is used for excluding the rectangular area which is erroneously detected as the single character and is within the range of the preset buffer area outside the minimum circumscribed rectangle according to the preset range of the center of the rectangular area within the range of the preset buffer area outside the minimum circumscribed rectangle of the single character;
and the third exclusion subunit is used for excluding at least one of the rectangular areas in the preset buffer area range outside the minimum external rectangle falsely detected as the single character according to the condition that the rectangular area in the preset buffer area range outside the minimum external rectangle of the single character and the rectangular area in the preset buffer area range outside the minimum external rectangle of other single characters form an overlapping area.
7. The apparatus of claim 6, wherein the condition is a shape of the overlapping region and/or a measured size and/or area of the overlapping region.
8. The apparatus of any of claims 5 to 7, wherein the correction module comprises:
the comparison unit is used for comparing the inclination angle with a preset angle range;
and the rotating unit is used for clockwise or anticlockwise rotating the rectangular area within the range of the preset buffer area outside the minimum external rectangle if the inclination angle belongs to the preset angle range.
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| CN107169489B (en) * | 2017-05-08 | 2020-03-31 | 北京京东金融科技控股有限公司 | Method and apparatus for tilt image correction |
| CN107239776B (en) * | 2017-05-08 | 2020-05-01 | 京东数字科技控股有限公司 | Method and apparatus for tilt image correction |
| CN107832757B (en) * | 2017-11-03 | 2021-08-31 | 深圳航天信息有限公司 | Invoice image identification method |
| JP6711523B2 (en) * | 2018-05-25 | 2020-06-17 | 株式会社ふくおかフィナンシャルグループ | Form recognition system |
| CN110312070B (en) * | 2019-04-23 | 2021-08-24 | 维沃移动通信有限公司 | Image processing method and terminal |
| CN110110697B (en) * | 2019-05-17 | 2021-03-12 | 山东省计算中心（国家超级计算济南中心） | Multi-fingerprint segmentation extraction method, system, device and medium based on direction correction |
| CN110647824B (en) * | 2019-09-03 | 2022-06-28 | 四川大学 | Value-added tax invoice layout extraction method based on computer vision technology |
| CN111832561B (en) * | 2020-07-03 | 2021-06-08 | 深圳思谋信息科技有限公司 | Character sequence recognition method, device, equipment and medium based on computer vision |
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