CN102196148B - Image processing method, image processing equipment and image scanning equipment - Google Patents
Image processing method, image processing equipment and image scanning equipment Download PDFInfo
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- CN102196148B CN102196148B CN201010116627.5A CN201010116627A CN102196148B CN 102196148 B CN102196148 B CN 102196148B CN 201010116627 A CN201010116627 A CN 201010116627A CN 102196148 B CN102196148 B CN 102196148B
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Abstract
The invention provides an image processing method, image processing equipment and image scanning equipment. The method can correct the shadow in the binding part on a scanned image of an opened book. The image processing method comprises the following steps of: determining the binding part, namely determining the binding part on the scanned image; generating a shadow data mapping graph, namely generating the shadow data mapping graph formed by the shadow data of the determined binding part according to the pixel value in the top part and the pixel value in the bottom part of the determined binding part; and correcting, namely correcting the shadow in the determined binding part by using the generated shadow data mapping graph. The implementation of the method is very quick, easy and cheap, and good correcting performance can be realized.
Description
Technical field
The present invention relates to a kind of image processing method, image processing equipment and image scanning apparatus, relate in particular to image processing method, image processing equipment and the image scanning apparatus of the shade in the bookbinding part on the scan image of the books that can proofread and correct expansion.
Background technology
Image reading apparatus (image scanning apparatus) is widely used in many occasions, and is particularly useful in office, library etc.The problem existing in normal image scanner is, in the time of the bookbinding document (will be called " books " below) of scanner scanning books type, rise above the flat of scanner in the bookbinding region of books, that is, leave the focal plane of scanner and erect.As a result, on scan image, the part (will be called " bookbinding part " below) corresponding to the bookbinding region of books distorts, has shade and fuzzy.Especially true for relatively thick books.
As one of current disclosed technology about shadow removal, United States Patent (USP) discloses for No. 6839459 a kind of by using the technology of the shade in the bookbinding part based on proofreading and correct from definite position to the one dimension grading function that is weighted of relative distance of bookbinding center line the scan image of books of expansion.Described grading function calculates according to page boundary and bookbinding center line.The shortcoming of the method is, in order to estimate accurate grading function, must very accurately detect page boundary and bookbinding center line.For example, but (in the time that the area of the book cover of books is greater than page), will be difficult to accurately detect page boundary when have interference in page boundary time.In addition,, in the time that the condition such as lighting condition in the head portion of books and the bookbinding region of bottom part is different (this causes may be pushed due to books time), cannot shadow model be described by single grading function in scanning.
United States Patent (USP) 6041146 has proposed a kind of method of carrying out the shade on correct scan image for the reference pressing plate adding by use, and described additional reference pressing plate is arranged on the position that is different from document surfaces, in order to record reference background information.But this additional reference pressing plate will increase hardware cost, and the method can not be for the treatment of the scan image obtaining by not having this scanner with reference to pressing plate.
US patent application publication discloses a kind of equipment for the shade on fine correction scan image No. 20080024845.In this equipment, analyze the pixel value of view picture input picture, to determine dash area, and analyze away from the dash area of top page edge and bottom margin edge compared with upper section with compared with the pixel value of below part, make by considering that two above analysis results determine the inclination of input picture.After determining and having adjusted the inclination of input picture, utilize the corrected value producing from the analysis result of view picture input picture, in every a line, implement to proofread and correct and process.By utilizing, the analysis result of view picture input picture is proofreaied and correct to shade in No. 20080024845 disclosed method of US patent application publication, thus very complicated, and spend a large amount of calculating.In addition the margin that, the method is not used conventionally the less top being interfered and lowermost end shadow information as a setting.
Summary of the invention
For the processing of bookbinding partial correction (removal) shade from scan image, in effectively removing shade, retain the word that prints on books and picture and not drop-out be important.
The present inventor notices, page-images for majority from books, top part and the lowermost end part of the page always have more white space than the interior section of the page, and most books even have the margin of complete blank in the top part of the page and lowermost end part.Can very well indicate about the background luminance background information of (it can be represented by pixel value) corresponding to the blank parts in the scan image of the white space in books, it only depends on that the lighting condition of scanning light source and books are placed on the mode on flat, and with books in the content of printing irrelevant.Therefore, the top part in bookbinding part and the blank parts in lowermost end part can be very useful extracting in this background information, because these parts are less subject to the interference of the content of printing in books.
In addition, the present inventor is also noted that the shade occurring in scan image does not generally have unexpected variation, and the pixel value of scan image is especially very mild and approach linear to the variation of bottom from top.
Consider the technical problem that exists and above-mentioned inventor's observation in above-mentioned prior art, image processing method, image processing equipment and the image scanning apparatus of the shade in the bookbinding part on the scan image of the books that can proofread and correct expansion is provided.According to the present invention, generate the shadow data mapping graph for this bookbinding part according to the pixel value (expression brightness) in top part and lowermost end part in the bookbinding part of scan image, then remove shade according to generated shadow data mapping graph from bookbinding part.
According to an aspect of the present invention, a kind of image processing method is provided, described image processing method can be proofreaied and correct the shade in the bookbinding part on the scan image of books of expansion, described image processing method comprises the steps: to bind part determining step, determines the bookbinding part on scan image; Shadow data mapping graph generates step, according to the pixel value in the top part of determined bookbinding part and the pixel value in lowermost end part, generates the shadow data mapping graph being made up of the shadow data of determined bookbinding part; And aligning step, by using the shadow data mapping graph generating, proofread and correct the shade in determined bookbinding part.
According to an aspect of the present invention, a kind of image processing equipment is provided, described image processing equipment can be proofreaied and correct the shade in the bookbinding part on the scan image of books of expansion, and described image processing equipment comprises: bookbinding part determining device, for determining the bookbinding part on scan image; Shadow data mapping graph generating apparatus, for according to the pixel value in pixel value and the lowermost end part of the top part of determined bookbinding part, generates the shadow data mapping graph being made up of the shadow data of determined bookbinding part; And means for correcting, for by using the shadow data mapping graph generating, proofread and correct the shade in determined bookbinding part.
According to an aspect of the present invention, provide a kind of image scanning apparatus, comprising: read control device, for read expansion books image with generate scan image; And image processing equipment as above.
According to a preferred embodiment of the present invention, can be for example by first passing through to use the pixel value in determined bookbinding top part and lowermost end part partly to estimate the determined top of part and the shadow data of bottom of binding, generate other shadow datas outside determined bookbinding top and bottom partly thereby then determined shadow data of binding top partly and bottom is carried out to interpolation, generate whole determined bookbinding shadow data mapping graph partly.
According to a further advantageous embodiment of the invention, for each row of determined bookbinding part, N pixel of search and the top of these row and the central pixel value corresponding to the brightest pixel of N pixel of lowermost end respectively, and the use described pixel value corresponding with the brightest described pixel is respectively as the shadow data of top and the bottom of these row, wherein row are pixel columns parallel with the left border of determined bookbinding part or right side boundary, and N is predetermined positive integer.
According to a further advantageous embodiment of the invention, after estimating shadow data for each row, process the top of determined bookbinding part and the shadow data of bottom, the misdata in estimated shadow data is corrected.
According to a further advantageous embodiment of the invention, in order to generate shadow data mapping graph, first generation and the determined blank shadow data mapping graph partly with formed objects of binding, the shadow data of then filling the estimated shadow data of determined bottom of binding the estimated shadow data on top partly, determined bookbinding part and generating from described interpolation in blank shadow data mapping graph.
Preferably, can be before shadow correction, the geometric distortion of correct scan image during shadow correction or after shadow correction.
According to of the present invention for the image processing method of proofreading and correct shade completely based on scan image data itself, without any need for additional auxiliary equipment, do not require yet and accurately detect page boundary.
Further, according to only top part and the lowermost end part of the determined bookbinding part of analysis scan image of image processing method for proofreading and correct shade of the present invention.Specifically, do not need to analyze the shadow data mapping graph that pixel value (expression brightness) in whole determined bookbinding part is identified for proofreading and correct the shade in whole determined bookbinding part, but only the top part based on determined bookbinding part and this shadow data mapping graph of calculated for pixel values of lowermost end part.Therefore, according to of the present invention for the method for proofreading and correct shade fast, not expensive and easily implement.
From the description referring to accompanying drawing, other property features of the present invention and advantage will become clear.
Brief description of the drawings
Be incorporated in specification and form the accompanying drawing diagram embodiments of the invention of a specification part, and together with the description for principle of the present invention is described.
Fig. 1 is the block diagram that the hardware configuration of the computer system 1000 that can implement embodiments of the invention is shown.
Fig. 2 illustrates according to of the present invention for proofreading and correct the block diagram of image processing equipment 2000 of shade of bookbinding part of scan image of books of expansion.
Fig. 3 is the flow chart of the processing of the shade in the bookbinding part illustrating on the scan image of proofreading and correct the books that launch.
Fig. 4 is the flow chart that the exemplary process of the bookbinding part on the scan image of books of definite expansion is according to a preferred embodiment of the invention shown.
Fig. 5 illustrates the example for the determined books border of the scan image of the books that launch.
Fig. 6 illustrates the determined bookbinding part in the scan image of books of the expansion of the example shown in Fig. 5.
Fig. 7 is the flow chart that the exemplary process of generation shadow data mapping graph is according to a preferred embodiment of the invention shown.
Fig. 8 is the schematic diagram that the example of error recovery shadow data is shown.
Fig. 9 illustrates the example of the shadow data mapping graph generating for the determined bookbinding part in the example shown in Fig. 6.
Figure 10 illustrates the example of the scan image after the shadow correction by the shadow correction market demand shown in Fig. 9 is obtained in the determined bookbinding part shown in Fig. 6.
Embodiment
Describe embodiments of the invention in detail hereinafter with reference to accompanying drawing.
Note that similar Reference numeral and similar project in character indicator diagram, once and in a width figure, defined a project, not need to after figure in it is discussed.
First, by the implication of some terms under explanation linguistic context of the present invention.
Term " books " refers to the document of the bind type by multiple sheet stitchings are formed together.Term " bookbinding region " refers to the region that comprises bookbinding center line and periphery thereof of the books of expansion.Term " bookbinding part " refers to the part in the bookbinding region corresponding to these books of the scan image of the books of expansion.
Term " top part " refers to the part of at least a portion of the top margin comprising books in scan image.Term " lowermost end part " refers to the part of at least a portion on the border, bottom comprising books in scan image.
Term " parallel " refers to substantially parallel.In the present invention, if two straight lines are called as " parallel ", this refers to that they form the angle that is less than predetermined threshold.Term " orthogonal " refers to substantially orthogonal.In the present invention, if two straight lines are called as " orthogonal ", this refers to that the difference between angle and 90 degree that they form is less than predetermined threshold.The above-mentioned loose definition for term " parallel " and " orthogonal " is especially useful for the image of distortion.
Term " level " refers to substantial horizontal, and term " vertically " refers to perpendicular.In particular, the term " level " using in the file and picture of distortion refers to direction parallel with line of text in original document.For example, term " horizontal line " refers to that the line corresponding to this line is parallel with the line of text in original document in original document.Similarly, the term " vertically " in the file and picture of distortion refers in corresponding original document orthogonal with line of text.For example, term " vertical line " refers in original document orthogonal corresponding to the line of text in line and the original document of this line.
Term " left side ", " right side ", " top " and " end " instruction direction in the time that the common mode when normally reading as people is watched books.
Term " shadow data mapping graph " refers to the mapping between the each pixel in the bookbinding part on shadow information and scan image.Be noted that shadow data mapping graph can have various forms.For example, shadow data mapping graph can have the form of form or mapping graph, and its shadow data by each pixel in the bookbinding part on scan image forms, and for proofreading and correct shade.The shadow data of a pixel can be the data of the estimated background pixel value (expression brightness) of this pixel of instruction.Described pixel value for example can be in 0～255 scope.As an alternative solution, shadow data mapping graph can have the form of shadow data function, and wherein shadow data is represented as mathematic(al) representation but not each single numerical value.As another alternative, shadow data mapping graph can have the form of correction function, and for example, in the time that the input of correction function is the original hypographous image of tool (being represented by pixel value), as the output of described correction function, by the image generating after proofreading and correct.In addition, shadow data can be the estimated pixel value of former state, or can be also by the normalized pixel value of the pixel value presetting.In brief, the concept of shadow data mapping graph should not be limited aspect its concrete form.
In this manual, unless pointed out by other modes, all sizes (such as length or width) are taking " pixel " as unit.
In the present invention, in the time mentioning two distances between line segment, it indicates these two line segments to be regarded as the distance therebetween in situation parallel to each other.When these two line segments not lucky time parallel to each other, distance therebetween for example can be by the mid point from a line segment distance definition to another line segment.
Fig. 1 is the block diagram that the hardware configuration of the computer system 1000 that can implement embodiments of the invention is shown.
As shown in Figure 1, computer system comprises computer 1110.Computer 1110 comprises the processing unit 1120, system storage 1130, fixed non-volatile memory interface 1140, removable non-volatile memory interface 1150, user's input interface 1160, network interface 1170, video interface 1190 and the output peripheral interface 1195 that connect via system bus 1121.
System storage 1130 comprises ROM (read-only memory) 1131 and RAM (random access memory) 1132.BIOS (basic input output system) 1133 resides in ROM 1131.Operating system 1134, application program 1135, other program module 1136 and some routine data 1137 reside in RAM 1132.
Fixed non-volatile memory 1141 such as hard disk is connected to fixed non-volatile memory interface 1140.Fixed non-volatile memory 1141 for example can storage operation system 1144, application program 1145, other program module 1146 and some routine data 1147.
Removable nonvolatile memory such as floppy disk 1151 and CD-ROM drive 1155 is connected to removable non-volatile memory interface 1150.For example, floppy disk can be inserted in floppy disk 1151, and CD (CD) can be inserted in CD-ROM drive 1155.
Input equipment such as mouse 1161 and keyboard 1162 is connected to user's input interface 1160.
Computer 1110 can be connected to remote computer 1180 by network interface 1170.For example, network interface 1170 can be connected to remote computer 1180 by local area network (LAN) 1171.Or network interface 1170 can be connected to modulator-demodulator (modulator-demodulator) 1172, and modulator-demodulator 1172 is connected to remote computer 1180 via wide area network 1173.
Remote computer 1180 can comprise the memory 1181 such as hard disk, and it stores remote application 1185.
Video interface 1190 is connected to monitor 1191.
Output peripheral interface 1195 is connected to printer 1196 and loud speaker 1197.
Computer system shown in Fig. 1 is only illustrative and is never intended to any restriction to invention, its application, or uses.
Computer system shown in Fig. 1 can be incorporated in any embodiment, can be used as stand-alone computer, also can be used as the treatment system in equipment, can remove one or more unnecessary assemblies, also can add one or more additional assemblies to it.
Fig. 2 illustrates according to of the present invention for proofreading and correct the block diagram of image processing equipment 2000 of shade of bookbinding part of scan image of books of expansion.As shown in Figure 2, image processing equipment 2000 comprises: bookbinding part determining device 2100, for determining the bookbinding part on scan image; Shadow data mapping graph generating apparatus 2300, for according to the pixel value in pixel value and the lowermost end part of the top part of determined bookbinding part, generates the shadow data mapping graph being made up of the shadow data of determined bookbinding part; And means for correcting 2500, for by using the shadow data mapping graph generating, proofread and correct the shade in determined bookbinding part.
Preferably, described shadow data mapping graph generating apparatus 2300 comprises: top estimation unit 2310, for the pixel value of the top part by using determined bookbinding part, estimate the shadow data on the top of determined bookbinding part; Bottom estimation unit 2330, for the pixel value of the lowermost end part by using determined bookbinding part, estimates the shadow data of the bottom of determined bookbinding part; And interpolating apparatus 2350, carry out interpolation for the top to determined bookbinding part and the shadow data of bottom, thereby generate other shadow datas outside determined bookbinding top and bottom partly.
Preferably, described bookbinding part determining device 2100 comprises: for determining the top margin of books and the device 2110 on border, bottom that launch; And for determining the left border of described bookbinding part and the device 2130 of right side boundary, top margin or the border, bottom of the described left border of determined bookbinding part and the books of right side boundary and described expansion are orthogonal.
Preferably, described top estimation unit 2310 comprises: for each row for determined bookbinding part, pixel value corresponding to the brightest pixel that search is central with N pixel of the top of these row, and the use described pixel value corresponding with the brightest described pixel is as the device 2311 of the shadow data on the top of these row, wherein row are pixel columns parallel with the left border of determined bookbinding part or right side boundary, and N is predetermined positive integer; And/or for after estimating shadow data for each row, process the shadow data on the top of determined bookbinding part, the device 2313 that the misdata in estimated shadow data is corrected.
Preferably, described bottom estimation unit 2330 comprises: for each row for determined bookbinding part, pixel value corresponding to the brightest pixel that search is central with N pixel of the lowermost end of these row, and the use described pixel value corresponding with the brightest described pixel is as the device 2331 of the shadow data of the bottom of these row, wherein row are pixel columns parallel with the left border of determined bookbinding part or right side boundary, and N is predetermined positive integer; And/or for after estimating shadow data for each row, process the shadow data of the bottom of determined bookbinding part, the device 2333 that the misdata in estimated shadow data is corrected.
Preferably, described shadow data mapping graph generating apparatus 2300 also comprises: for generating and determined bookbinding part has the device 2370 of the blank shadow data mapping graph of formed objects, and for fill the estimated shadow data of bottom and the device 2390 of the shadow data that generates from described interpolation of estimated shadow data, determined bookbinding part on top of determined bookbinding part at blank shadow data mapping graph.
Preferably, described image processing equipment 2000 also comprises distortion correction device 2700, for the geometric distortion of correct scan image.
More than device is the exemplary and/or preferred module for implementing the following process that will describe.Module for implementing each step is not below at large described.But, as long as there is the step of carrying out certain process, just can be useful on corresponding functional module or the device of implementing same process.The technical scheme limiting by all combinations of step described below and the device corresponding with these steps is all included in the application's disclosure, as long as these technical schemes that their form are complete and applicable.
In addition the said system being made up of various devices, can be used as in the hardware unit that functional module is incorporated into scanner or photocopier and so on.Except these functional modules, scanner or photocopier can have other hardware or software part certainly.
To describe according to the exemplary and/or preferred embodiment of image processing method of the present invention below.
Fig. 3 is the flow chart that the processing of the shade in the bookbinding part of scan image of proofreading and correct the books that launch is shown.
In step S301, the scan image of the books that input launches.
In step S303, the bookbinding part on the scan image of definite books that launch.A lot of prior art documents have proposed estimation by utilizing for example distribution of the pixel value to bookbinding center line or whole scan image determines or locates the whole bag of tricks of the bookbinding part in the scan image of books of expansion.The technology of any definite bookbinding part well known in the prior art all can be used.Especially,, because the present invention does not need binding accurately determining of part, therefore only the method for rough definite bookbinding part also can be used at this, and can not adversely influence technique effect.
In step S305, by using the pixel value in determined bookbinding top part and lowermost end part partly, generate shadow data mapping graph for determined bookbinding part.For example can generate shadow data mapping graph by determined bookbinding part being divided into multiple little parts and generating respectively shadow data for each in these little parts.In a preferred embodiment, the pixel value corresponding with pixel the brightest in the middle of pixel in each region in multiple regions in top part and lowermost end part can be used to generate the shadow data mapping graph of determined bookbinding part.
In step S307, by using the shadow data mapping graph generating to remove the shade in (correction) determined bookbinding part.
By this way, obtain the scan image with shadeless bookbinding part.
Below, some preferred embodiments will be described.It should be noted that following preferred embodiment can implement individually, or also can implement with any combination.
As mentioned above, the present invention can adopt the method for the bookbinding part of the rough scan image of determining the books that launch.Below provide a kind ofly for determining the simple of bookbinding part and mode easily, it does not need the distribution of the pixel value of estimating bookbinding center line or view picture scan image.
Fig. 4 is the flow chart that the exemplary process of the bookbinding part on the scan image of books of definite expansion is according to a preferred embodiment of the present invention shown.The exemplary process of the process for performing step S303 has been described in processing in this flow chart shown in Fig. 4, and can after step S301, carry out.
In step S401, the books border in the scan image of definite books that launch.In prior art, disclose for the various technology at image locating rectangle object, any such technology is all used in this and determines books border.For example, can determine as follows the books border in the scan image of books launching.
First,, by utilizing general edge detection method, such as the edge detection method that utilizes Sobel operator or Canny operator etc., from scan image, produce edge image.Then, select the long level curve of the top in edge image as books border, top, and select in edge image below long level curve as books border, bottom.After this, select the long vertical line of the leftmost side in edge image as books border, left side, and select the long vertical line of the rightmost side in edge image as books border, right side.Thereby, from scan image, detect the whole border of books.The generation of edge image and utilization are being known in the art, and therefore will here not describe in detail.
Also can use the additive method for determining books border.For example, books border, left side and books border, right side not the vertical line from edge image detect, but can consider books border, top and books border, bottom towards determining with end.In this case, can only use about books border, top and books border, bottom towards with the information of end, and without producing or estimating books border, left side and books border, right side.
Fig. 5 illustrates the example for the determined books border of the scan image of the books that launch.
In step S403, after having determined books border, the geometric distortion of correct scan image before proofreading and correct shade.It should be noted that this step is optional, because geometric distortion does not almost affect the present invention.In addition,, even if books were tilted and put in scan period, also can implement the present invention and not make hydraulic performance decline.That is to say, some geometric distortions are also acceptables, and do not make performance degradation of the present invention.As an alternative solution, the correction of geometric distortion also can be removing enforcement after shade, and this and relation of the present invention are little, will be not in this description.
In step S405, determine that left border determines that position and right side boundary determine position, wherein said left border determine position on books border, left side the right side of (or the left end on top or books border, bottom), and apart from books border, left side (or the left end on top or books border, a bottom) W pixel, described right side boundary determine position on books border, right side the left side of (or the right-hand member on top or books border, bottom), and apart from books border, right side (or the right-hand member on top or books border, a bottom) W pixel, wherein W is given threshold value, and equal certain ratio (for example books width * 0.3) of books width, wherein said books width is defined as the distance between books border, left side (or the left end on top or books border, bottom) and books border, right side (or the right-hand member on top or books border, bottom).
At step S407, determine bookbinding portion boundary.
Particularly, for the scan image that has been corrected geometric distortion, books border, top is two parallel straightways with books border, bottom, and they are set as bookbinding top margin and border, bottom partly.Produce respectively through above-mentioned left border determine position and right side boundary determine position and with orthogonal two parallel lines of top margin and border, bottom, as left border and the right side boundary of described bookbinding part.
For the scan image that is not corrected geometric distortion, be similar to from the books border, top of distortion and books border, bottom and two straight lines obtaining are provided as bookbinding top margin and border, bottom partly.Produce respectively through above-mentioned left border determine position and right side boundary determine position and with the top margin of bookbinding part and border, bottom in two one of at least orthogonal parallel lines, as left border and the right side boundary of described bookbinding part.
Then,, after having determined top margin, border, bottom, left border and the right side boundary of bookbinding part, described bookbinding part is determined.
Fig. 6 illustrates the determined bookbinding part in the scan image of books of the expansion of the example shown in Fig. 5.
Fig. 7 is the flow chart that the exemplary process of generation shadow data mapping graph is according to a preferred embodiment of the present invention shown.The exemplary process of the processing for performing step S305 has been described in processing in flow chart shown in Fig. 7, and can after step S303, carry out.
In step S701, by estimate the shadow data on the top of determined bookbinding part by the top part of determined bookbinding part.The top part of determined bookbinding part can be defined as whole pixels in determined bookbinding part, be equal to or less than N pixel to the distance of determined bookbinding top margin partly, and wherein N is predetermined positive integer.For example, this threshold value can be set as N ≈ 0.1* books height, and wherein said books height is defined as the distance between determined bookbinding top margin and border, bottom partly.
Preferably, can be to classify the shadow data on the determined bookbinding of estimated by unit top partly as.At this, " row " refer to the pixel column parallel with the left border of determined bookbinding part or right side boundary.For each row of determined bookbinding part, pixel value corresponding to the brightest pixel in the top part of search and these row, and the pixel value corresponding with the brightest described pixel obtaining is reserved as the shadow data on the top of these row.By this way, each row has the data point as the shadow data on the top for these row.
In the middle of the obtained shadow data for top, some row may the vicious shadow data of tool.The shadow data of mistake may be that noise or form line etc. cause.In order to proofread and correct possible wrong shadow data, preferably can apply post-processing step here.For example, the shade in the scan image of the books that launch by observation, can obtain following criterion: the shade on bookbinding center line is the darkest, and along with move to the both sides of determined bookbinding part from bookbinding center line, it is more shallow that shade becomes.Described reprocessing can be carried out and proofread and correct possible wrong shadow data, to make meeting above criterion or similar criterion.
For example, in described reprocessing, check estimated shadow data, removal does not meet above criterion or the data point of similar criterion, and replace removed data point by the value of the data point in adjacent row or for example, by the value (, the mean value of the value of the data point in the adjacent row on the left side and the adjacent row on the right) of the data point calculation from adjacent row.Fig. 8 is the schematic diagram that the example of the shadow data of error recovery is shown.Circle symbol in Fig. 8 represents the correct data point of shadow data, triangle symbol represents wrong data point, it has the higher value of value than the adjacent row of more approaching bookbinding center line, and square symbols represents for the data after the correction of wrong data point, the data after described correction are by the value of the data point in the adjacent row on the adjacent row in left side and right side is averaging and is obtained.
As an alternative solution, in order to proofread and correct the mistake in the shadow data of top part, also the other technologies such as curve can be applied to these data points, to suppress the irregular variation in shadow data.
In step S703, by estimate the shadow data of the bottom of determined bookbinding part by the lowermost end part of determined bookbinding part.The lowermost end part of determined bookbinding part can be defined as whole pixels in determined bookbinding part, be equal to or less than N pixel to the distance on determined bookbinding border, bottom partly, and wherein N is predetermined positive integer.For example, this threshold value can be set as N ≈ 0.1* books height, and wherein said books height is defined as the distance between determined bookbinding top margin and border, bottom partly.
Preferably, can be to classify the shadow data of the determined bookbinding of estimated by unit bottom partly as.At this, " row " have the implication identical with the implication of " row " described for the top of determined bookbinding part.For each row of determined bookbinding part, pixel value corresponding to the brightest pixel in the lowermost end part of search and these row, and the pixel value corresponding with the brightest described pixel obtaining is reserved as the shadow data of the bottom of these row.By this way, each row has the data point as the shadow data of the bottom for these row.
In the middle of the obtained shadow data for bottom, some row may the vicious shadow data of tool.The shadow data of mistake may be that noise or form line etc. cause.In order to proofread and correct possible wrong shadow data, preferably can here apply and the similar post-processing step of post-processing step of describing for top.For example, described reprocessing can be identical with the reprocessing of describing for top above.
Please note, although from the flow chart of Fig. 7, the estimation of the shadow data to bottom appears in the estimation of the shadow data to top and carries out afterwards, but the estimation of the shadow data to bottom can be carried out before the estimation of the shadow data to top, or can carry out concurrently the estimation of the estimation of the shadow data to top and the shadow data to bottom.That is to say, the present invention does not limit the time sequencing of the estimation for carrying out the shadow data to top and bottom.
In step S705, the top to determined bookbinding part and the shadow data of bottom carry out interpolation, make to estimate the shadow data between top and the bottom in determined bookbinding part.
Particularly, for each row of determined bookbinding part, carry out interpolation by the shadow data of the top to these row and bottom, obtain the shadow data between top and the bottom in these row.
Utilize the interpolation of vertical direction, even if books were tilted and the geometric distortion of scan image are not proofreaied and correct in scan period, the performance that the present invention still can obtain.
By this way, can obtain all shadow datas of all row in determined bookbinding part.
In step S707, for example, can generate in such a way shadow data mapping graph.
First, can first generate blank shadow data mapping graph.Described blank shadow data mapping graph can have the size identical with determined bookbinding part, and each pixel on described blank shadow data mapping graph is corresponding to the pixel in the same position in determined bookbinding part.Then,, for each row of blank shadow data mapping graph, be filled in the corresponding top and bottom position on blank shadow data mapping graph on the top of determined bookbinding part and the shadow data of bottom.Then, for each row of blank shadow data mapping graph, the shadow data in other parts beyond the top of bookbinding part that obtain as the result of interpolation, determined and bottom, determined bookbinding part is filled in the corresponding position on blank shadow data mapping graph.
By this way, generate the shadow data mapping graph for whole determined bookbinding part.Although more than described the concrete mode of one that generates shadow data mapping graph in detail, generated the method for shadow data mapping graph and the detailed formation of described shadow data mapping graph itself and be not limited to above-mentioned concrete mode.For example, in the foregoing description, first describe and how to have generated each shadow data, then described shadow data is filled in each position in blank shadow data mapping graph.But, can implement as follows above-mentioned processing: first generate blank shadow data mapping graph, then every next pixel ground, generates a shadow data and a described shadow data be filled in the relevant position in blank shadow data mapping graph simultaneously.In addition,, according to above description, the data point in shadow data mapping graph is to be the estimated pixel value of pixel in determined bookbinding part.But the data point in shadow data mapping graph can also be by the normalized normalization pixel value of scheduled pixel value.In addition, as explained above, shadow data mapping graph also can have the form of mathematic(al) representation.Therefore, just enough as long as shadow data mapping graph can characterize the distribution of shade in determined bookbinding part.In addition, shadow data mapping graph can be accepted such as the further processing for correction error or enhancing picture quality.
Fig. 9 illustrates the example of the shadow data mapping graph generating for the determined bookbinding part in the example shown in Fig. 6.Can find out, shadow data mapping graph has characterized the distribution of the shade of background, and does not comprise any word or relevant information of picture with printing in books.
To describe according to a preferred embodiment of the present invention by the exemplary process that uses the shadow data mapping graph generating to remove the shade in (correction) determined bookbinding part below.This processing can be carried out in step S307, after step S305, carries out.
For example, can be according to following formula correction the pixel value in the determined bookbinding part on hypographous scan image:
D(x，y)＝M*I(x，y)/S(x，y)
Wherein, D (x, y) be at position (x in determined bookbinding part, the pixel value (pixel value after correction) of the pixel after the correction of y) locating, I (x, y) be at position (x in determined bookbinding part, the pixel value (original pixel value) of the pixel before the correction of y) locating, S (x, y) be for position (x, the shadow data value of the pixel of y) locating, and M is the pixel value of representative " ideal " background pixel value.Equal I (x when locating S (x, y) in certain position (x, y), y) time, that is to say, in the time that the shadow data of this position equals the original pixel value of this position, this means that this position is in background parts (blank parts).In this case, the pixel value D (x, y) after correction equals to represent the M of " ideal " background pixel value.Therefore, can find out, the original pixel value in background parts is transformed into " ideal " pixel value M by the method according to this invention, regardless of its original pixel value.For example, M can be set to the pixel value of pixel the brightest in the whole shadow data part before correction.As an alternative solution, M can be also other predetermined pixel value.In this case, thereby also can adjust the pixel value in the non-shaded portion in scan image, make the background pixel value after proofreading and correct there is uniform value.
Above-mentioned formula about the example of how to proofread and correct the pixel value in hypographous bookbinding part with shadow data mapping graph.But, use the concrete grammar of described shadow data mapping graph not limited by above-mentioned formula.Can apply weight coefficient W (x, y), make by I (x, y) weighting is obtained to D (x, y).Also can utilize shadow data mapping graph proofread and correct before, during or afterwards, apply as required other processing.
Figure 10 illustrates the example of the scan image after the shadow correction by the shadow correction market demand shown in Fig. 9 is obtained in the determined bookbinding part shown in Fig. 6.As seen from Figure 10, the shade occurring in the bookbinding part of scan image of the books that launch is removed well.
Can proofread and correct the shade in the bookbinding part of scan image of the books of expansion with above image processing method and equipment.Described image processing method can be configured to equipment the equipment separating with scanner (image scanning apparatus), or can be structured in scanner.In the time that image processing method according to the present invention and equipment are structured in scanner, they can be configured to the part of the image processing part of scanner, and can be stored in the storage device of scanner and use for controller according to the form of program.In this case, above-mentioned image processing equipment can form the functional module of scanner.Reading reading images (scan image) that control part obtained the books that launch afterwards, then can carry out above-mentioned image processing method according to image processing equipment of the present invention, with the shade in the bookbinding part of correct scan image.Thus, the user of scanner can obtain (after shadow removal) image shadow correction and without any need for the effort of further processing image immediately from scanner.In the situation that scanner is incorporated into photocopier, the shade that the user of photocopier can obtain wherein the image of the books that launch is corrected the copy of (shade is removed).
In addition, certainly, also can be before image processing method according to the present invention, during or afterwards, carry out other image processing process such as geometric distortion correction.
Can implement method and apparatus of the present invention by many modes.For example, can implement method and apparatus of the present invention by software, hardware, firmware or its any combination.The order of above-mentioned method step is only illustrative, and method step of the present invention is not limited to above specifically described order, unless otherwise clearly stated.In addition, in certain embodiments, the present invention can also be implemented as the program being recorded in recording medium, and it comprises the machine readable instructions for realizing the method according to this invention.Thereby the present invention also covers the recording medium of storing the program for realizing the method according to this invention.
Although by example detail display specific embodiments more of the present invention, it will be appreciated by those skilled in the art that above-mentioned example is only intended that exemplary and does not limit the scope of the invention.It should be appreciated by those skilled in the art that above-described embodiment to be modified and do not depart from the scope and spirit of the present invention.Scope of the present invention is to limit by appended claim.
Claims (17)
1. an image processing method, described image processing method can be proofreaied and correct the shade in the bookbinding part on the scan image of books of expansion, and described image processing method comprises the steps:
Bookbinding part determining step, determines the bookbinding part on scan image;
Shadow data mapping graph generates step, and only the pixel value in the top part based on determined bookbinding part and the pixel value in lowermost end part, generate the shadow data mapping graph being made up of the shadow data of determined bookbinding part; And
Aligning step, by using the shadow data mapping graph generating, proofreaies and correct the shade in determined bookbinding part,
Wherein said shadow data mapping graph generates step and comprises the steps:
Top estimating step, by using the pixel value in determined bookbinding top part partly, estimates the shadow data on the top of determined bookbinding part;
Bottom estimating step, by using the pixel value in determined bookbinding lowermost end part partly, estimates the shadow data of the bottom of determined bookbinding part; And
Interpolation procedure, the top to determined bookbinding part and the shadow data of bottom carry out interpolation, thereby generate other shadow datas outside determined bookbinding top and bottom partly.
2. image processing method according to claim 1, wherein said bookbinding part determining step comprises the steps:
Determine top margin and the border, bottom of the books that launch; And
Left border and the right side boundary of determining described bookbinding part, top margin or the border, bottom of the described left border of determined bookbinding part and the books of right side boundary and described expansion are orthogonal.
3. image processing method according to claim 1, wherein said top estimating step comprises the steps:
For each row of determined bookbinding part, pixel value corresponding to the brightest pixel that search is central with N pixel of the top of these row, and the use described pixel value corresponding with the brightest described pixel is as the shadow data on the top of these row, wherein row are pixel columns parallel with the left border of determined bookbinding part or right side boundary, and N is predetermined positive integer.
4. image processing method according to claim 3, wherein said top estimating step further comprises the steps:
After estimating shadow data for each row, process the shadow data on the top of determined bookbinding part, the misdata in estimated shadow data is corrected.
5. image processing method according to claim 1, wherein said bottom estimating step comprises the steps:
For each row of determined bookbinding part, pixel value corresponding to the brightest pixel that search is central with N pixel of the lowermost end of these row, and the use described pixel value corresponding with the brightest described pixel is as the shadow data of the bottom of these row, wherein row are pixel columns parallel with the left border of determined bookbinding part or right side boundary, and N is predetermined positive integer.
6. image processing method according to claim 5, wherein said bottom estimating step further comprises the steps:
After estimating shadow data for each row, process the shadow data of the bottom of determined bookbinding part, the misdata in estimated shadow data is corrected.
7. according to the image processing method described in any one in claim 1-6, wherein, described shadow data mapping graph generates step and further comprises the steps:
Generate the blank shadow data mapping graph with determined bookbinding part with formed objects, and
The shadow data of filling the estimated shadow data of determined bottom of binding the estimated shadow data on top partly, determined bookbinding part and generating from described interpolation in blank shadow data mapping graph.
8. according to the image processing method described in any one in claim 1-6, further comprise:
Distortion correction step, the geometric distortion of correct scan image.
9. an image processing equipment, described image processing equipment can be proofreaied and correct the shade in the bookbinding part on the scan image of books of expansion, and described image processing equipment comprises:
Bookbinding part determining device, for determining the bookbinding part on scan image;
Shadow data mapping graph generating apparatus, for the pixel value in pixel value and the lowermost end part of the top part based on determined bookbinding part only, generates the shadow data mapping graph being made up of the shadow data of determined bookbinding part; And
Means for correcting, for by using the shadow data mapping graph generating, proofreaies and correct the shade in determined bookbinding part,
Wherein said shadow data mapping graph generating apparatus comprises:
Top estimation unit, for the pixel value of the top part by using determined bookbinding part, estimates the shadow data on the top of determined bookbinding part;
Bottom estimation unit, for the pixel value of the lowermost end part by using determined bookbinding part, estimates the shadow data of the bottom of determined bookbinding part; And
Interpolating apparatus, carries out interpolation for the top to determined bookbinding part and the shadow data of bottom, thereby generates other shadow datas outside determined bookbinding top and bottom partly.
10. image processing equipment according to claim 9, wherein said bookbinding part determining device comprises:
For determining the top margin of books and the device on border, bottom that launch; And
For determining the left border of described bookbinding part and the device of right side boundary, top margin or the border, bottom of the described left border of determined bookbinding part and the books of right side boundary and described expansion are orthogonal.
11. image processing equipments according to claim 9, wherein said top estimation unit comprises:
For each row for determined bookbinding part, pixel value corresponding to the brightest pixel that search is central with N pixel of the top of these row, and the use described pixel value corresponding with the brightest described pixel is as the device of the shadow data on the top of these row, wherein row are pixel columns parallel with the left border of determined bookbinding part or right side boundary, and N is predetermined positive integer.
12. image processing equipments according to claim 11, wherein said top estimation unit further comprises:
For after estimating shadow data for each row, process the shadow data on the top of determined bookbinding part, the device that the misdata in estimated shadow data is corrected.
13. image processing equipments according to claim 9, wherein said bottom estimation unit comprises:
For each row for determined bookbinding part, pixel value corresponding to the brightest pixel that search is central with N pixel of the lowermost end of these row, and the use described pixel value corresponding with the brightest described pixel is as the device of the shadow data of the bottom of these row, wherein row are pixel columns parallel with the left border of determined bookbinding part or right side boundary, and N is predetermined positive integer.
14. image processing equipments according to claim 13, wherein said bottom estimation unit further comprises:
For after estimating shadow data for each row, process the shadow data of the bottom of determined bookbinding part, the device that the misdata in estimated shadow data is corrected.
15. according to the image processing equipment described in any one in claim 9-14, and wherein, described shadow data mapping graph generating apparatus further comprises:
For generating the device with determined bookbinding part with the blank shadow data mapping graph of formed objects, and
For fill the estimated shadow data of bottom and the device of the shadow data that generates from described interpolation of the estimated shadow data on the top of determined bookbinding part, determined bookbinding part at blank shadow data mapping graph.
16. according to the image processing equipment described in any one in claim 9-14, further comprises:
Distortion correction device, for the geometric distortion of correct scan image.
17. 1 kinds of image scanning apparatus, comprising:
Read control device, for read expansion books image with generate scan image; And
According to the image processing equipment described in any one in claim 9-16.
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