JP4706612B2 - Image processing apparatus and image processing program - Google Patents

Description

  The present invention relates to an image processing apparatus and an image processing program.

  Conventionally, as a technique for specifying a location to be added to a predetermined document such as a form, Japanese Patent Application Laid-Open Publication No. 2003-28259 discloses that after pre-addition image and post-addition image alignment, before-addition image data and post-addition image There has been disclosed a technique for extracting a postscript portion by performing monochromatic / binarization of data and subtracting the pre-write image data from the post-write image data obtained thereby.

  In Patent Document 2, the images before and after the additional recording are divided into a predetermined number, the images are aligned for each divided region, and then the image before the additional recording is expanded, and the image data before the additional recording and the image data after the additional recording are added. A technique for extracting a postscript location by calculating an exclusive OR for each pixel of the above is disclosed.

  Japanese Patent Application Laid-Open No. 2004-228688 extracts a first storage unit that stores image data, a conversion unit that converts a document file into image data, and extracts difference information that is a difference between the two images by comparing the two image data. There is disclosed a document filing apparatus having difference information extracting means for performing the above and second storage means for storing the extracted difference information.

Further, Patent Document 4 discloses a technique for extracting a difference after storing divided position information in a barcode and adding it to a print document, and performing area division and alignment based thereon.
JP 2004-80601 A JP 2004-341914 A Japanese Patent Laid-Open No. 2003-115039 JP 2003-18393 A

  The present invention has been made in the technical background as described above, and provides an image processing apparatus and an image processing program capable of specifying with high accuracy the location of additional writing performed on a halftone image. Objective.

  In order to achieve the above object, an image processing apparatus according to a first aspect of the present invention provides first image information indicating an image of a document before additional writing and a first image indicating the image of the original after additional recording is performed. Acquisition means for acquiring two-image information as each pixel information composed of a plurality of bits having a predetermined number of bits, and the first image information and the second image information acquired by the acquisition means Deriving means for deriving third image information by subtracting pixel information for each corresponding pixel, and zero or more by the predetermined number of bits in the third image information derived by the deriving means The pixel information that is out of the numerical range that can be expressed as an integer is canceled with the pixel information of the pixel whose distance from the pixel corresponding to the pixel information is within a predetermined distance, and the offset by the canceling unit And a, specifying means for specifying a location where the additional recording is performed based on the third image information.

  The invention according to claim 2 is the invention according to claim 1, wherein the predetermined distance is the first image information and the second image information when the third image information is derived by the deriving means. Is a distance corresponding to an assumed maximum deviation amount between corresponding pixels.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the canceling unit is a pixel outside the numerical range in the third image information derived by the deriving unit. A calculating unit that calculates an amount of information that is out of the numerical range; and an amount calculated by the calculating unit is calculated by calculating a distance from a pixel corresponding to the pixel information that is the target of calculating the amount in the third image information. Dispersing means for canceling the pixel information of the pixels within the predetermined distance by dispersing the pixel information within a range that falls within the numerical range.

  Furthermore, the invention according to claim 4 is the pixel information according to claim 3, wherein the distribution unit uses the amount calculated by the calculation unit as a calculation target of the amount in the third image information. The pixel information of the pixels whose distance from the pixel corresponding to is within the predetermined distance is dispersed within the range that falls within the numerical range in order of increasing distance.

  On the other hand, in order to achieve the above object, an image processing program according to claim 5 includes: first image information indicating an image of a document before additional recording is performed; and an image of the document after additional recording is performed. An acquisition step of acquiring the second image information to be shown as each pixel information comprising a plurality of bits of a predetermined number of bits, the first image information acquired by the acquisition step, and the second A derivation step for deriving third image information by subtracting pixel information for each corresponding pixel from the image information, and zero based on the predetermined number of bits in the third image information derived by the derivation step The pixel information that falls outside the numerical range that can be expressed as an integer is offset with the pixel information of a pixel whose distance from the pixel corresponding to the pixel information is within a predetermined distance. It is intended to execute the up and the computer.

  According to the first and fifth aspects of the invention, as a result of suppressing the occurrence of noise caused by the positional deviation between the pre-recording image and the post-recording image, the location of the additional recording performed on the halftone image Can be specified with high accuracy.

  Further, according to the second aspect of the invention, an effect that the processing time can be shortened can be obtained.

  In addition, according to the third aspect of the present invention, there is an effect that the pixel information can be appropriately dispersed.

  Furthermore, according to the fourth aspect of the present invention, there is an effect that pixel information can be more appropriately dispersed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a configuration example of an image processing system 10 to which the present invention is applied. As shown in the figure, the image processing system 10 according to the present embodiment includes an image processing device 20 such as a personal computer and an image reading device 30 such as a scanner. The image processing device 20 and the image reading device 30 are electrically connected, and the image processing device 20 can acquire image data obtained by reading by the image reading device 30 from the image reading device 30.

  The image processing system 10 according to the present embodiment includes a document before additional writing by handwriting or stamping (hereinafter referred to as “original document before adding”) and a document after the additional writing (hereinafter referred to as “original document”). , “Added document”) is read by the image reading device 30, and based on the two image data obtained by this, the image processing device 20 identifies the location where the additional recording has been performed, and appends from the identified location. The extracted image portion is extracted. In the following, image data obtained by reading a document before appending is referred to as “image data before appending”, and image data obtained by reading a document after appending is referred to as “image data after appending”.

  The image reading device 30 according to the present embodiment acquires image data obtained by reading as each pixel value (pixel information) is composed of a plurality of bits (8 bits in the present embodiment). ing. In the image processing system 10 according to the present embodiment, the image reading apparatus 30 separates and reads an image of a document to be read into three primary colors R (red), G (green), and B (blue). A color scanner is applied.

  Next, with reference to FIG. 2, the main configuration of the electrical system of the image processing apparatus 20 having a particularly important role in the image processing system 10 will be described.

  As shown in the figure, the image processing apparatus 20 according to the present embodiment includes a CPU (central processing unit) 20A that controls the operation of the entire image processing apparatus 20, and a work area when the CPU 20A executes various processing programs. A RAM (Random Access Memory) 20B, a ROM (Read Only Memory) 20C in which various control programs and various parameters are stored in advance, a hard disk 20D that is a storage means used to store various information, and various types A keyboard 20E used for inputting information, a display 20F used for displaying various types of information, and an input / output interface (I / F) 20G for exchanging various types of information with external devices are provided. These units are electrically connected to each other by a system bus BUS. Here, the image reading device 30 described above is connected to the input / output interface 20G.

  Accordingly, the CPU 20A accesses the RAM 20B, ROM 20C and hard disk 20D, acquires various input information via the keyboard 20E, displays various information on the display 20F, and various information with the image reading device 30 via the input / output interface 20G. Can be exchanged.

  FIG. 3 is a functional block diagram showing a functional configuration of the image processing apparatus 20 according to the present embodiment. As shown in the figure, the image processing apparatus 20 according to the present embodiment includes a calculation unit 22, a pixel value canceling unit 24, a write-once specifying unit 26 including a conversion unit 26A and a specifying unit 26B, and a storage unit 28. And.

  The calculation unit 22 performs a subtraction operation of the pixel value for each pixel corresponding to the pre-addition image data and the post-addition image data acquired by the image reading device 30, and the image data (hereinafter referred to as “image data”) obtained thereby. "Calculation result image data") is output. In the image processing system 10 according to the present embodiment, color image data composed of R, G, and B is applied as image data to be processed. Therefore, the calculation unit 22 performs the above subtraction operation as R, G. , B separately.

  Here, if the pixel value of the pre-recording image data is AV and the pixel value of the post-recording image data at the corresponding position is BV, the calculation unit 22 configures the calculation result image data by the following equation (1). The pixel value RV to be obtained can be obtained.

RV = (255−BV) − (255−AV)
= AV-BV (1)
By the way, the subtraction result by the equation (1) is that the portion without additional writing is generally 0 (zero), and the additional writing portion has a value within the range of 1 to 255. An image is obtained using the calculation result image data obtained thereby. In the case of display or printing, an inverted image (negative image) is shown. Therefore, in this case, the subtraction result obtained by the expression (1) may be subtracted from the pixel value 255 corresponding to the white background. That is, by applying the following equation (2), it is possible to prevent an image when displayed or printed from being an inverted image.

RV = 255-{(255-BV)-(255-AV)}
= BV-AV + 255 (2)
FIG. 4A shows an example of the image before the additional recording indicated by the image data before the additional recording obtained by reading the portion where the halftone image is formed in the document before the additional recording by the image reading device 30. 4B, the post-recording image indicated by the post-recording image data obtained by reading the part of the halftone image after the additional recording is performed so as to overlap the halftone image. An example is shown.

  On the other hand, FIG. 5A shows pixel values in the A1-A2 cross section of the pre-append image shown in FIG. 4A, with R as an example, and the vertical axis is 255-Red (R pixels). Value). FIG. 5B shows the pixel value in the A1-A2 cross section of the post-recording image shown in FIG. 4B by taking R as an example, and the vertical axis is the same as in FIG. Is 255-Red (R pixel value). Further, FIG. 5C is calculated by inputting the pre-recording image data indicating the pre-recording image data shown in FIG. 4A and the post-recording image data indicating the post-recording image data shown in FIG. 7 shows pixel values of an A1-A2 cross section in an image indicated by calculation result image data output from the unit 22.

  As shown in FIG. 5C, since the pixel value hardly changes between the pre-addition image and the post-addition image except at the location where the additional recording is performed, the calculation result is almost 0 (zero). In the place where the process is performed, a change in the pixel value due to the additional writing appears as a calculation result. Therefore, the portion where the change appears can be specified as the portion where the additional writing has been performed.

  The above description is for the case where the pre-recording image data and post-recording image data are RGB image data. These image data are represented by C (cyan), M (magenta), and Y (yellow). If the color image data is composed or color image data composed of the four colors C, M, Y and K (black), the calculation result image data is composed of the following equation (3). The pixel value RV to be obtained can be obtained.

RV = BV-AV (3)
By the way, the actual pre-recording image data and post-recording image data include image sensors such as a CCD sensor and a CMOS image sensor provided in the image reading device 30, and a result for forming an image on the image sensor. Due to scratches or dust in the image optical system or the like, noises such as noises a to h are often included as shown in FIGS. 6A and 6B as an example. In addition, in the subtraction calculation by the calculation unit 22, it is ideal that the positions of corresponding pixels in the pre-addition image data and the post-addition image data are coincident with each other. There are many cases. In order to avoid this, it is common to perform alignment between each image data of the image data before additional recording and the image data after additional recording, but even if the alignment is performed, Since it is difficult to correct, it is extremely difficult to make them completely coincide.

  Therefore, when the subtraction operation is performed by the arithmetic unit 22 under such a situation, noise remains as shown in FIG. 6C as an example. Here, the noise that has become a negative value by the subtraction operation (in the example shown in FIG. 6C, noises a, f, c, h) is set to 0 to remove the noise. However, the noise having a positive value (in the example shown in FIG. 6C, noise e, b, g, d) remains.

  Therefore, the pixel value canceling unit 24 is out of a numerical value range (here, a range of 0 or more and 255 or less) that can be expressed as an integer of zero or more by the number of bits constituting the pixel value in the calculation result image data. Is offset with the pixel value of a pixel whose distance from the pixel corresponding to the pixel value is within a predetermined distance.

  That is, as described above, the reason why the noise remains is that the positions of the corresponding pixels in the pre-recording image data and the post-recording image data are slightly shifted. For this reason, there is an extremely high possibility that there is a pixel having a pixel value whose absolute value is substantially the same as that of the pixel value and has the opposite sign in the vicinity of the pixel whose pixel value is outside the above numerical range. .

  By using this point, the pixel value canceling unit 24 uses a pixel value that is out of the numerical value range in the calculation result image data as a pixel value of a pixel whose distance from the pixel corresponding to the pixel value is within a predetermined distance. It is supposed to be offset. Increasing the predetermined distance naturally increases the possibility of changing a pixel value that is not noise, and also reduces the processing speed. Therefore, the predetermined distance is limited to an appropriate range. Preferably, in the pixel value cancellation unit 24 according to the present embodiment, as the predetermined distance, between the corresponding pixels of the pre-addition image data and the post-addition image data when the calculation result image data is derived by the calculation unit 22 The distance corresponding to the assumed maximum deviation amount is applied. Needless to say, the present invention is not limited to this configuration, and a distance or the like corresponding to an amount obtained by adding a predetermined amount as a margin to the maximum deviation amount can be applied.

  By the way, the inventors of the present invention, color image data composed of R, G, B, color image data composed of C, M, Y, or color composed of C, M, Y, K. After the calculation result image data output from the calculation unit 22 using the image data as input data is converted into image data in the HLS color space, the portion overlapping the halftone image of the additional recording portion of the same color and the halftone image are overlapped. As a result of comparison with the non-existing portion, it was found that although there was a large difference in luminance L and saturation S, the difference in hue H was extremely small.

  Therefore, the conversion unit 26A converts the calculation result image data output from the pixel value canceling unit 24 into image data of a predetermined color space (HLS color space in the present embodiment) having a hue H. Convert to image data.

  Then, the specifying unit 26B specifies the location where the additional recording has been performed based on the converted image data obtained by the conversion unit 26A, and stores the information indicating the location where the additional recording has been performed in the storage unit 28. In the image processing system 10 according to the present embodiment, range information indicating a range of at least one of the hue H, the luminance L, and the saturation S including the color of additional writing is received, and the specifying unit 26 In the converted image data, the position of the pixel included in the range indicated by the range information is specified as the location where the additional writing has been performed.

  Note that the processing by each component (the calculation unit 22, the pixel value canceling unit 24, the conversion unit 26A, and the specifying unit 26B) of the image processing apparatus 20 configured as described above uses a computer by executing a program. It can be realized by a software configuration. In this case, the program includes the image processing program of the present invention. However, the present invention is not limited to realization by a software configuration, and needless to say, it can also be realized by a hardware configuration or a combination of a hardware configuration and a software configuration.

  Hereinafter, a description will be given of a case where the image processing system 10 according to the present embodiment is configured to realize processing by each of the above-described components by executing the above-described program (hereinafter referred to as “image processing program”). To do. In this case, the image processing program is installed in the image processing apparatus 20 in advance, provided in a state stored in a computer-readable recording medium, or distributed via wired or wireless communication means. Forms and the like can be applied.

  Next, the operation of the image processing system 10 according to the present embodiment will be described with reference to FIG. FIG. 7 is a flowchart showing a flow of processing of an image processing program executed by the CPU 20A of the image processing apparatus 20. Here, in order to avoid complications, only the processing by the arithmetic unit 22 and the pixel value canceling unit 24 particularly related to the present invention will be described. Furthermore, here, in order to avoid complications, the pre-recording image data and post-recording image data to be processed are input from the image reading apparatus 30 as indicating the same size original document image, and are previously stored in a predetermined area of the hard disk 20D. The case where it is stored will be described.

  In step 100 of the figure, the pre-addition image data and post-addition image data to be processed are acquired by reading from the hard disk 20D, and in the next step 102, the width of the image indicated by each read image data (here, The number of pixels in the horizontal direction of the image is substituted into the variable W, and the height of the image (here, the number of pixels in the vertical direction of the image) is substituted into the variable T.

  In the next step 104, 0 is substituted for the variable i. In the next step 106, 0 is substituted for the variable k. In the next step 108, the height direction position in the pre-addition image data and the post-addition image data. Is subtracted for each R, G, B pixel value using the pixel value at the position indicated by the value of the variable i and the position in the width direction indicated by the value of the variable k. . As described above, in the image processing program according to the present embodiment, the subtraction operation according to the equation (2) is performed in the present step 108. However, the present invention is not limited to this. Needless to say. Note that the pre-additional image indicated by the pre-additional image data and the post-additional image indicated by the post-additional image data are caused by a difference in the inclination angle between the pre-addition original and the post-addition original when read by the image reading device 30. Then, since the corresponding pixel position may be shifted, it is preferable to align each image data using a conventionally known technique prior to the execution of the subtraction operation. This form is applied to the image processing program according to the above.

  In the next step 110, the value of the variable k is incremented by 1. In the next step 112, it is determined whether or not the value of the variable k is less than the value of the variable W (a value indicating the width of the image). If the determination is affirmative, the process returns to step 108, and the processing after step 108 is executed again. On the other hand, if the determination is negative, the process proceeds to step 114.

  In step 114, the value of the variable i is incremented by 1. In the next step 116, it is determined whether or not the value of the variable i is less than the value of the variable T (value indicating the height of the image). If the determination is affirmative, the process returns to step 106, and the processing after step 106 is executed again. On the other hand, if the determination is negative, the process proceeds to step 118. Through the above processing, calculation result image data is obtained. The processing from step 102 to step 116 corresponds to the processing of the calculation unit 22.

  In step 118, 0 is substituted for the variable i, and in the next step 120, 0 is substituted for the variable k. In the next step 122, the height direction position in the image indicated by the calculation result image data is the variable i. The pixel value (pixel value for each of R, G, and B) at the position indicated by the value and the position in the width direction indicated by the value of the variable k is an integer greater than or equal to zero depending on the number of bits constituting the pixel value. It is determined whether it is within a predetermined range that can be expressed (in this embodiment, within a range of 0 or more and 255 or less). If a negative determination is made, the process proceeds to step 124 to be described later. After executing the pixel value cancellation processing routine program to be executed, the routine proceeds to step 126. If the determination in step 122 is affirmative, the process proceeds to step 126 without executing the pixel value cancellation processing routine program in step 124.

  In step 126, the value of variable k is incremented by 1. In the next step 128, it is determined whether or not the value of variable k is less than the value of variable W. Returning to 122, the process from step 122 onward is executed again. On the other hand, if a negative determination is made, the process proceeds to step 130.

  In step 130, the value of variable i is incremented by 1. In the next step 132, it is determined whether or not the value of variable i is less than the value of variable T. Returning to 120, the processing from step 120 onward is executed again. On the other hand, if a negative determination is made, the image processing program ends.

  Next, the pixel value cancellation processing routine program according to the present embodiment will be described with reference to FIG. Here, the pixel at the position in which the height direction position in the image indicated by the calculation result image data is indicated by the value of the variable i and the position in the width direction is indicated by the value of the variable k is referred to as a “target pixel”. Called.

  In step 200 in the figure, a deviation amount X of the pixel value of the target pixel from the predetermined range (in the present embodiment, a range from 0 to 255) is calculated. In the image processing program according to the present embodiment, the subtraction operation is performed according to the expression (2). Therefore, the portion without additional writing is approximately 255, and the additional writing portion has a value within the range of 1 to 255. Accordingly, in this step 200, the deviation amount X is calculated by the following equation (4). Here, TV is the pixel value of the pixel of interest.

X = TV-255 (4)
In the next step 202, the pixel value TV of the pixel of interest is clamped to the predetermined range (in this embodiment, the pixel value TV is set to 255). In the next step 204, the deviation amount X is set to the pixel of interest. To the pixel value of the nearest pixel (hereinafter referred to as “addition target pixel”). Here, when there are a plurality of pixels closest to the target pixel, any of these pixels may be set as the addition target pixel.

  In the next step 206, it is determined whether or not the pixel value of the pixel to be added is within the predetermined range. If the determination is affirmative, this pixel value cancellation processing routine program is terminated, If YES in step 208, the flow advances to step 208, and the amount of deviation X of the pixel value KV of the addition target pixel from the predetermined range is calculated by the following equation (5).

X = KV-255 (5)
In the next step 210, the pixel value KV of the pixel to be added is clamped to the predetermined range (in this embodiment, the pixel value KV is set to 255). In the next step 212, the target pixel and the target pixel The distance from the pixel to the pixel next closest to the pixel to be added is the predetermined distance (here, between corresponding pixels of the pre-addition image data and the post-addition image data when deriving the calculation result image data) The distance corresponding to the assumed maximum deviation amount) is less than or equal to, and if the determination is affirmative, the process returns to step 204, and the processing after step 204 is executed again. At this point, the pixel value cancellation processing routine program is terminated. Note that, when the processes in steps 204 to 212 are repeatedly executed, pixels that have not been added as pixels to be added are applied as pixels to be added. In addition, when there is a pixel that is the same distance from the pixel of interest as the addition target pixel and is not the addition target pixel at the time of executing step 212, the pixel is moved to the next. Apply as close pixel. Here, when there are a plurality of pixels whose distance from the target pixel is the same distance as the addition target pixel and are not set as the addition target pixel, any of these pixels is set as the next closest pixel. You may apply.

  The processing of Step 200 of the pixel value cancellation processing routine program corresponds to the calculation means of the present invention, and the processing of Steps 204 to 212 corresponds to the distribution means of the present invention.

  Next, the processing contents by the above pixel value cancellation processing routine program will be described with reference to specific numerical examples shown in FIG.

  When the pixel value of the pixel of interest in the calculation result image data and the pixel value adjacent to the periphery thereof are as shown in FIG. 9A, first, as shown in FIG. 9A, the pixel value “270” of the pixel of interest. ”Is calculated as 15 (= 270-255).

  Next, the deviation amount X “15” is added to the pixel value “254” of the pixel nearest to the pixel of interest (here, the pixel in contact with the pixel of interest), and the result is shown in FIG. 9B. Thus, the pixel value is temporarily set to “269”, but since this value is out of the predetermined range, 14 (= 269-255) is calculated as the outlier X from the pixel value. At the same time, the pixel value is clamped to 255.

  Next, the calculated deviation amount X “14” is added to the pixel value “255” of the pixel closest to the pixel of interest (here, the pixel in contact with the pixel of interest below), thereby FIG. As shown in (C), the pixel value is temporarily set to “269”. However, since this value is out of the predetermined range, 14 (= 269-255) ) Is calculated, and the pixel value is clamped to 255.

  In the above processing, the distance from the pixel of interest is the predetermined distance (here, the maximum assumed between the corresponding pixels of the pre-addition image data and the post-addition image data when the calculation unit 22 derives the calculation result image data). Execute repeatedly until the pixel value after adding the deviation amount X is within the predetermined range (until the deviation amount X becomes 0 (zero)), with the upper limit being a pixel closer to the distance (distance corresponding to the deviation amount). Is done.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. Various modifications or improvements can be added to the above-described embodiment without departing from the gist of the invention, and embodiments to which such modifications or improvements are added are also included in the technical scope of the present invention.

  The above embodiments do not limit the invention according to the claims (claims), and all the combinations of features described in the embodiments are essential for the solution of the invention. Is not limited. The above-described embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. Even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, as long as an effect is obtained, a configuration from which these some constituent requirements are deleted can be extracted as an invention.

  For example, in the above embodiment, the case where the image processing is realized by the software configuration has been described. However, the present invention is not limited to this, and for example, the image processing is realized by the hardware configuration. You can also. As an example of the form in this case, for example, a function of executing the same processing as each component (the arithmetic unit 22, the pixel value canceling unit 24, the converting unit 26A, the specifying unit 26B) of the image processing apparatus 20 illustrated in FIG. The form which creates and uses a device can be illustrated. In this case, the image processing can be speeded up as compared with the above embodiment.

  In the above embodiment, the case where the HLS color space is applied as the color space having the hue has been described. However, the present invention is not limited to this, and for example, other colors having the hue such as the HSV color space. A color space may be applied. In this case as well, the same effects as in the above embodiment can be obtained.

  In addition, the configurations (see FIGS. 1 to 3) of the image processing system 10 and the image processing apparatus 20 described in the above embodiment are merely examples, and unnecessary portions are deleted without departing from the gist of the present invention. Needless to say, you can add new parts.

  Further, various arithmetic expressions described in the above embodiment (see Expressions (1) to (5)) are also examples, and it goes without saying that changes can be made without departing from the gist of the present invention.

  Furthermore, the processing flow (see FIGS. 7 and 8) of the image processing program and the pixel value cancellation processing routine program described in the above embodiment is also an example, and is unnecessary within the scope of the present invention. It goes without saying that steps can be deleted, new steps can be added, and the processing order can be changed.

1 is a block diagram illustrating a configuration of an image processing system according to an embodiment. It is a block diagram which shows the principal part structure of the electric system of the image processing apparatus which concerns on embodiment. It is a functional block diagram which shows the functional structure of the image processing apparatus which concerns on embodiment. It is a figure with which it uses for description of the calculation by the calculating part which concerns on embodiment, and is a top view which shows an example of the image before additional recording and the image after additional recording. It is a figure with which it uses for description of the calculation by the calculating part which concerns on embodiment. It is a figure where it uses for description of the noise contained in the image data before additional recording which concerns on embodiment, and image data after additional recording. It is a flowchart which shows the flow of a process of the image processing program concerning embodiment. It is a flowchart which shows the flow of a process of the pixel value cancellation process routine program which concerns on embodiment. It is a figure with which it uses for the concrete description of the processing content by the pixel value cancellation process routine program which concerns on embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image processing system 20 Image processing apparatus 20A CPU
20D hard disk 20E keyboard 22 calculation unit (derivation means)
24 pixel value canceling unit (offset means)
26 Addendum identification part (identification means)
28 storage unit 30 image reading device (acquisition means)

Claims (5)

A plurality of first image information indicating an image of a document before additional recording and second image information indicating an image of the original after additional recording are set to a plurality of bits each having a predetermined number of pixel information. An acquisition means for acquiring the data as comprising bits;
Deriving means for deriving third image information by subtracting pixel information for each corresponding pixel of the first image information and the second image information acquired by the acquiring means;
Pixel information that is out of a numerical range that can be expressed as an integer greater than or equal to zero by the predetermined number of bits in the third image information derived by the deriving means has a predetermined distance from the pixel corresponding to the pixel information. Canceling means for offsetting the pixel information of the pixels within the distance;
Specifying means for specifying a location where the additional recording is performed based on the third image information canceled by the canceling means;
An image processing apparatus. The predetermined distance is a distance corresponding to an assumed maximum shift amount between corresponding pixels of the first image information and the second image information when the third image information is derived by the deriving unit. Item 6. The image processing apparatus according to Item 1. The offset means is
Calculating means for calculating an amount of pixel information out of the numerical range of the third image information derived by the deriving means out of the numerical range;
The amount calculated by the calculating means is converted into the numerical value range of the pixel information of a pixel whose distance from the pixel corresponding to the pixel information for which the amount is calculated in the third image information is within the predetermined distance. Dispersion means for performing the cancellation by dispersing within a range to be accommodated;
The image processing apparatus according to claim 1, further comprising: The distribution unit converts the amount calculated by the calculation unit into pixel information of a pixel whose distance from a pixel corresponding to the pixel information for which the amount is calculated in the third image information is within the predetermined distance. The image processing apparatus according to claim 3, wherein the distances are dispersed within a range that falls within the numerical range in ascending order of the distance. A plurality of first image information indicating an image of a document before additional recording and second image information indicating an image of the original after additional recording are set to a plurality of bits with each pixel information determined in advance. An acquisition step for acquiring as consisting of bits;
A derivation step of deriving third image information by subtracting pixel information for each corresponding pixel of the first image information and the second image information acquired by the acquisition step;
Pixel information that is out of a numerical range that can be expressed as an integer greater than or equal to zero by the predetermined number of bits in the third image information derived by the deriving step has a predetermined distance from the pixel corresponding to the pixel information. An offset step that offsets pixel information for pixels that are within a distance;
An image processing program for causing a computer to execute.

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