JP2013157965A - Image processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve quality of a read image of a document.SOLUTION: An image processing apparatus for reading an image of a document, includes: an exposure adjusting unit for increasing/decreasing a light amount of a light source; an image reading unit for illuminating light from the light source adjusted in the exposure adjusting unit to the document to read image information including a luminance value for each pixel, and reading the image information of the document for the at least every two light amounts adjusted; a halation pixel detecting unit for detecting a halation pixel at which the luminance value for each pixel included in the image information read by increasing the light amount exceeds a threshold, to detect a pixel column including the halation pixel; a luminance difference calculating unit for calculating a difference between a maximum value and a minimum value of the luminance value in each pixel column of the image information; a pixel column combining unit for generating an intermediate image obtained by selecting and combining a pixel column having the largest difference between the maximum value and the minimum value of the luminance value and not including the halation pixel; and a luminance correcting unit for performing luminance correction of the intermediate image.

Description

  The present invention relates to an image processing apparatus that reads an image of a document.

  In order to improve the image quality of a dark portion of a read image generated at a place where a bound original is lifted from a mounting table, a conventional image processing apparatus includes an optical system using a plurality of point light sources, and the reading optical system is There is one in which the light amount of the light source is increased when the document is moved to a position near the center of the document (for example, see Patent Document 1).

JP 2002-314760 A (paragraphs “0114” to “0120”, FIGS. 11 and 15)

However, in the conventional technology, it is difficult to appropriately adjust the light amount according to the height of the central portion of the document from the mounting table, and there is a problem that sufficient quality of the read image of the document cannot be obtained. is there.
An object of the present invention is to solve such a problem and to improve the quality of a read image of a document.

  Therefore, according to the present invention, in an image processing apparatus that reads an image of a document, an exposure adjustment unit that increases or decreases the light amount of a light source, and the light of the light source adjusted by the exposure adjustment unit is irradiated on the document to obtain a luminance value for each pixel. An image reading unit that reads image information including the image information and reads the image information of the document for each of the adjusted at least two light amounts; and a luminance value for each pixel included in the image information read by increasing the light amount has a threshold value. A whiteout pixel detection unit that detects an overexposed whiteout pixel and detects a pixel row including the whiteout pixel, and calculates a difference between the maximum value and the minimum value of the luminance values in each pixel row of the image information. A luminance difference calculation unit and a pixel row that has the largest difference between the maximum value and the minimum value of the luminance values and does not include the whiteout pixel among all the read image information for each pixel row. Intermediate image synthesized by selecting A pixel column combining part to be generated, characterized in that a luminance correction unit for performing luminance correction of the intermediate image.

  According to the present invention as described above, it is possible to improve the quality of the read image of the document.

The block diagram which shows the control structure of the scanner in a 1st Example. External view showing the configuration of the scanner in the first embodiment Side surface explanatory drawing of the scanning part in 1st Example The flowchart which shows the flow of the brightness correction processing in the first embodiment. Explanatory drawing which shows the loading state of the original in a 1st Example Luminance value distribution chart in the first embodiment Explanatory drawing of the captured image in 1st Example Histogram of brightness value of captured image in the first embodiment Explanatory drawing of the image of the correction result in 1st Example Histogram after correction in the first embodiment The flowchart which shows the flow of the pixel row composition process in the first embodiment. Explanatory drawing of calculation of the number of whiteout pixels in the first embodiment The block diagram which shows the control structure of the scanner in a 2nd Example. Explanatory drawing of the preview screen of the correction result in 2nd Example Explanatory drawing of the reading acceptance screen in 2nd Example The flowchart which shows the flow of the brightness correction process in 2nd Example. The flowchart which shows the flow of the pixel row image synthetic | combination process in 2nd Example.

  Embodiments of an image processing apparatus according to the present invention will be described below with reference to the drawings.

FIG. 2 is an external view showing the configuration of the scanner in the first embodiment.
In FIG. 2, reference numeral 100 denotes a scanner as an image processing apparatus that reads an image of an original, and reads an original placed on a mounting table and generates image information of the original.
The scanner 100 includes a scanning unit 1, a mounting table 2, an operation button 3, a start button 4, a display panel 5, and a cover 6.

  The scanning unit 1 obtains image information of a document while moving in the sub-scanning direction indicated by an arrow B in the drawing. As shown in FIG. 3, the scanning unit 1 includes a light source 21 and an image sensor 22 that obtains image information in the main scanning direction indicated by an arrow A in the figure, and moves while moving in the sub-scanning direction indicated by an arrow B in the figure. 21 is applied to the original 51, and the reflected light is received by the image sensor 22 and converted into an electrical signal, thereby obtaining image information including a luminance value as luminance information for each pixel. In the present embodiment, the luminance value represents 256 gradations from 0 to 255, for example.

The mounting table 2 is a glass table or the like on which a document to be scanned (including a bound document) is mounted. A scanning unit 1 that can move in the sub-scanning direction indicated by an arrow B in the drawing is arranged below the mounting table 2, and the scanning unit 1 reads image information of a document placed on the mounting table 2.
The operation button 3 accepts a user's input operation, and is an input means for inputting an instruction such as a cursor movement operation or a selection operation as an electric signal.

The start button 4 accepts a user's input operation, and is an input means for inputting an instruction for starting or stopping a document reading operation as an electric signal.
The display panel 5 is a display unit such as a display for displaying the state of the scanner 100 and various information based on the signal input by the operation button 3.
The cover 6 covers the mounting table 2 in order to block ambient light from the outside when the scanning unit 1 reads a document placed on the mounting table 2.

FIG. 1 is a block diagram showing the control configuration of the scanner in the first embodiment.
In FIG. 1, a scanner 100 includes an image reading unit 7, a storage unit 8, an exposure adjustment unit 9, a whiteout pixel detection unit 10, a luminance difference calculation unit 11, a pixel column synthesis unit 12, and a luminance correction unit. 13 and includes a CPU (Central Processing Unit) as a control unit (not shown), and the operation of the entire scanner 100 is controlled by the control unit based on a control program (software) stored in the storage unit 8. .

The image reading unit 7 controls the scanning unit 1 shown in FIG. 2, detects the pressing of the start button 4, reads a document (including a bound document) placed on the placing table 2, and reads the document. Image information is generated from the electrical signal.
The storage unit 8 includes storage means such as a memory, and stores information on the light amount (hereinafter referred to as “light source light amount”) of the light source 21 of the scanning unit 1 shown in FIG.

  The exposure adjustment unit 9 reads information on the light source light amount from the storage unit 8 and changes (increases / decreases) the light source light amount when the scanning unit reads the document. The image reading unit 7 reads the image information including the luminance value for each pixel by irradiating the original with the light of the light source adjusted by the exposure adjusting unit 9. In addition, the image reading unit 7 outputs image information based on the standard light source light amount and the light source light amount (standard) adjusted by the exposure adjustment unit 9 as image information of the original document for each of at least two light source light amounts adjusted by the exposure adjustment unit 9. Image information based on the light amount increased from the light source light amount).

  The whiteout pixel detection unit 10 detects a whiteout pixel in which the luminance value for each pixel included in the image information of the document acquired by the image reading unit 7 by increasing the light source light amount exceeds a threshold value. A pixel column including the detected pixel is detected, and the storage unit 8 stores that there is a pixel column including a pixel that is whitened by setting a whiteout flag. Here, an overexposed pixel means a pixel whose luminance value exceeds a predetermined threshold because the exposure amount of the reflected light of the light irradiated on the document exceeds the saturation exposure amount of the image sensor of the scanning unit. Say.

The luminance difference calculation unit 11 performs the maximum and minimum luminance values of the pixels in each pixel column for all pixel columns for which the whiteout pixel detection unit 10 has not set the whiteout flag in each pixel column of the image information. The difference from the value is obtained as a luminance difference.
The pixel row synthesizing unit 12 compares the luminance difference obtained by the luminance difference calculating unit 11 for each pixel column in the entire image information of the document acquired by the image reading unit 7, and selects (extracts) the pixel row having the largest luminance difference. ) To generate an intermediate image that is a basis for luminance correction. In other words, the pixel row composition unit 12 has the largest difference between the maximum value and the minimum value of the luminance value among all pieces of image information read by changing the light source light amount for each pixel row, and the pixels that are whiteout. An intermediate image is generated by selecting and synthesizing a pixel row that does not include.

For the intermediate image generated by the pixel column synthesizing unit 12, the luminance correction unit 13 calculates, for each pixel column, a ratio calculated so that the largest luminance value in the pixel column becomes the maximum luminance value (for example, 255). Brightness correction is performed to normalize the luminance value of each pixel by multiplying the luminance value of all the pixels in the pixel row, and a corrected image is output.
The operation of the above configuration will be described.

The brightness correction processing performed by the scanner will be described with reference to FIGS. 1 and 2 in accordance with the step represented by S in the flowchart showing the flow of the brightness correction processing in the first embodiment of FIG.
It is assumed that the scanner as the image processing apparatus has selected a bookbinding document reading mode for reading a document bound by a user operation (hereinafter referred to as “bookbinding document”).
The “pixel row” means a row of pixels parallel to the longitudinal direction of the binding portion in the image information of the bookbinding document. In this embodiment, the “pixel row” is displayed on the mounting table 2 as shown in FIG. This is a row of pixels parallel to the read marker 53.

  S1: The image reading unit 7 of the scanner 100 scans the scanning unit 1 using the exposure amount of the light source as the standard light amount, reads the bookbinding document 51 placed on the placing table 2 as shown in FIG. Image information is acquired, and the image information is stored in the storage unit 8. At this time, for example, as shown in FIG. 5, the scanner 100 prompts the user to place the bookbinding document 51 at a position where the reading marker 53 displayed on the mounting table 2 and the binding portion 52 of the bookbinding document 51 are aligned. The position of the binding portion 52 in the acquired image information of the bookbinding document 51 is specified by the position of the reading marker 53.

  S2: The exposure adjustment unit 9 changes (increases) the light amount of the light source of the scanning unit 1, the image reading unit 7 reads the bookbinding document 51 placed on the placing table 2, acquires the image information of the bookbinding document 51, The image information is stored in the storage unit 8. In this embodiment, the light source is an LED (Light Emitting Diode) light source, and the exposure value is changed by changing the current value of the LED light source and adjusting the lighting time. The amount of exposure can also be changed by changing the number of point light sources to be lit among the point light sources arranged in 1.

S3: When the scanner 100 determines that the number of readings of the bookbinding document 51 by the image reading unit 7 has reached a predetermined number of readings, the process proceeds to S4. When the scanner 100 determines that the number has not yet reached, the process proceeds to S2. . Note that the predetermined number of readings is a value selected according to the required accuracy of luminance correction, and is stored in the storage unit 8.
S4: The whiteout pixel detection unit 10 and the pixel row synthesis unit 12 of the scanner 100 generate an intermediate image used for luminance correction from the image information acquired in S1 and S2.
S5: The luminance correction unit 13 performs luminance correction for each pixel column on the intermediate image generated by the pixel column synthesis unit 12 in S4, outputs the corrected image, and ends the luminance correction process. Here, for the luminance correction, for example, a normalization method is used so that the maximum luminance value becomes 255.

Next, referring to FIG. 1 according to the step represented by S in the flowchart showing the flow of the pixel column synthesizing process in the first embodiment of FIG. 11, the pixel column synthesizing process performed by the control unit of the scanner in S4 described above. While explaining.
S41: The control unit of the scanner performs the processing of S42 to S47 for each pixel row 121a parallel to the longitudinal direction of the binding portion of the bookbinding original (reading marker 53) of the standard light quantity image information shown in FIG. repeat.

S42: The whiteout pixel detection unit 10 performs whiteout pixels for each pixel row 121a parallel to the longitudinal direction of the binding portion of the bookbinding original (reading marker 53) of the standard light quantity image information shown in FIG. The number N is calculated.
S43: The whiteout pixel detection unit 10 performs the processing of S44 to S46 on each piece of image information obtained by reading the bookbinding document by changing the light amount in S2 described above. Repeat as many times as read.

  S44: The whiteout pixel detection unit 10 changes the light quantity of the image information shown in FIG. 12B (read marker 53) for one piece of image information obtained by changing the light quantity and reading the bookbinding document, as in S42. That is, the number M of whiteout pixels is calculated for each pixel row 121c parallel to the longitudinal direction of the binding portion of the bookbinding document. The pixel column for calculating the number of whiteout pixels is a pixel column at the same position as the pixel row for which the number of whiteout pixels is calculated in S42. For example, when the pixel row for which the number of whiteout pixels is calculated in S42 is the i-th pixel row from the left end in the read image information, it is the i-th pixel row from the left end in the image information with the light amount changed.

  S45: The whiteout pixel detection unit 10 compares the number N of whiteout pixels calculated in S42 with the number of whiteout pixels M calculated in S44, and the number of whiteout pixels M is equal to or greater than a constant α from the number N of whiteout pixels. If so, the process proceeds to S46, and if the number M of overexposed pixels is not greater than the constant α by more than the constant α, the process proceeds to S44 where the number of overexposed pixels in the pixel row of the next image information is determined. calculate. Here, the constant α is a parameter set in advance according to the accuracy required by the user or according to the characteristics of the apparatus, and is stored in the storage unit 8.

S46: The whiteout pixel detection unit 10 that has determined that the number M of whiteout pixels is larger than the number N of whiteout pixels by a constant α is a whiteout flag for determining that the pixel row being processed is a whiteout pixel row. Is stored in the storage unit 8 to indicate that the pixel row being processed is a pixel row that is whiteout. When the storage unit 8 stores that the pixel row being processed is a whiteout pixel row, the whiteout pixel detection unit 10 moves the process to S44 and determines the number of whiteout pixels in the pixel row of the next image information. calculate.
When the processes in S44 to S46 are performed on the respective image information obtained by reading the bookbinding document with the light amount changed, the control unit shifts the process to S47.

  S47: When the processes of S44 to S46 are performed on the respective image information obtained by reading the bookbinding document with the light quantity changed, the pixel row composition unit 12 changes the image information of the standard light quantity and the respective image information with the light quantity changed. For the corresponding pixel row, the pixel row having the maximum luminance difference calculated by the luminance difference calculation unit 11 is selected from the pixel columns for which the whiteout flag is not set, and stored in the storage unit 8.

Here, the luminance difference dif (x) of the pixel row x is calculated by the following equation.
Brightness difference dif (x) = max (x) −min (x) (formula)
Note that max (x) is the maximum luminance value in the pixel column x, and min (x) is the minimum luminance value in the pixel column x.

  In the example of the image information in FIG. 12, since the whiteout flag is set in the pixel row 121c at the left end of the image in which the amount of light shown in FIG. 12B is changed, the whiteout flag is set. The pixel row 121a at the left end of the image having the standard light quantity shown in a) is selected, and the whiteout flag is not raised in the pixel row 121d near the binding portion of the bookbinding document of the image having the changed light quantity shown in FIG. If there is something, the brightness difference is compared between the pixel row 121d of the image in which the whiteout flag is not set and the pixel row 121b in the vicinity of the binding portion of the standard light quantity image shown in FIG. The pixel column 121d is selected.

The control unit that has performed the processes of S42 to S47 moves the process to S42 in order to perform the process of the next pixel column.
S48: When the processing of S42 to S47 is performed for all the pixel columns, the pixel column combining unit 12 combines the pixel columns stored in the storage unit 8 in S47 to generate an intermediate image.

In general, the illuminance on the surface of an object irradiated with light is inversely proportional to the square of the distance from the light source. Therefore, since the distance from the light source becomes large at the part of the document that has floated from the mounting table, the image information acquired by the image reading unit is as shown in FIG. 6 in the document binding unit (binding unit 52 in FIG. 5). The image information has a low luminance value.
Further, after changing the exposure amount of the light source in S2, the acquired image information of the bookbinding document is compared with the image acquired by irradiating the standard light amount of FIG. 7A as shown in FIG. 7B. As the illuminance on the surface of the document increases, the brightness of the binding portion 52 increases. On the other hand, the portion that is in close contact with the mounting table exceeds the saturation exposure amount of the image sensor, resulting in whiteout 54.

  This is represented by a histogram of luminance values for each pixel, as shown in FIG. 8. In an image obtained by irradiating a booklet original with a standard amount of light, the histogram of luminance values of a portion in close contact with the mounting table is shown in FIG. FIG. 8B shows a histogram of luminance values of the part floating from the mounting table. In addition, in an image acquired by irradiating a bookbinding document with light whose light amount is increased from the standard light amount, the histogram of the luminance value of the part in close contact with the mounting table is shown in FIG. The histogram of luminance values is as shown in FIG.

In the example of the image obtained as a result of performing the above-described brightness correction processing, as shown in FIG. 9, the brightness of the binding portion floating from the mounting table is high, and the histogram of the brightness value of the binding portion floating from the mounting table is As shown in FIG. 10, the number of pixels having a high luminance value increases and the number of pixels having a low luminance value decreases.
As described above, by performing the above-described brightness correction processing of S1 to S5, the distribution of the brightness value of the binding portion of the bookbinding document floating from the placing table becomes substantially uniform, and the image quality can be improved.

As described above, in the first embodiment, in addition to the image picked up with the standard light source exposure amount, the pixel row having the largest luminance difference is selected using the image picked up by increasing the light source exposure amount. By generating an intermediate image and performing brightness correction, it is possible to obtain an image with a sufficient exposure amount at each part on the document and to improve the quality of the read image of the document. It is done.
Further, the effect of improving the quality of the read image of the document can be obtained by performing simple exposure amount change and image processing even in the vicinity of the binding portion of the bound document.

  The configuration of the second embodiment is obtained by adding a reception unit and a display unit to the control configuration of the scanner of the first embodiment. The configuration of the second embodiment will be described based on the block diagram showing the control configuration of the scanner in the second embodiment of FIG. Note that parts similar to those of the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.

In FIG. 13, the scanner 100 includes an image reading unit 7, a storage unit 8, an exposure adjustment unit 14, a whiteout pixel detection unit 10, a luminance difference calculation unit 11, a pixel row synthesis unit 12, and a luminance correction unit. 15, a display unit 16, and a reception unit 17, and includes a CPU or the like as a control unit (not shown). The entire scanner 100 is based on a control program (software) stored in the storage unit 8 by the control unit. Operation is controlled.
The exposure adjusting unit 14 reads information on the light source light amount from the storage unit 8 in accordance with an instruction from the receiving unit 17 and changes the light source light amount when the scanning unit reads the document.

The luminance correction unit 15 performs luminance correction for each pixel column on the intermediate image generated by the pixel column synthesis unit 12 and outputs the corrected image to the display unit 16.
The display unit 16 displays an image as a result of the luminance correction performed by the luminance correction unit 15 on the display panel 5 as a preview screen 141 as shown in FIG. 14, for example.
For example, as illustrated in FIG. 15, the reception unit 17 further displays a screen on the display panel 5 that allows the user to select whether or not to read the original with the light source amount changed by the exposure adjustment unit 14. Thus, a selection operation for determining whether or not to read the original is accepted by the operation button.

The operation of the above configuration will be described.
The luminance correction processing performed by the scanner will be described with reference to FIGS. 2 and 13 in accordance with the step represented by S in the flowchart showing the flow of the luminance correction processing in the second embodiment of FIG. In the scanner as the image processing apparatus, it is assumed that a bookbinding document reading mode for reading a document that has been bound by a user operation is selected.

S101: Since it is the same process as S1 shown in FIG.
S102: The scanner 100 (pixel array synthesis unit 12) generates an intermediate image used for luminance correction from the image information acquired in S101 and S108. If the original image with the light amount changed is not read in S108, the original image read with the standard light amount is set as an intermediate image, and the process proceeds to S103 without performing this process.

S103: The luminance correction unit 13 performs luminance correction for each pixel column on the intermediate image generated by the pixel column synthesis unit 12 in S102. Here, for the luminance correction, for example, a normalization method is used so that the maximum luminance value becomes 255.
S104: The display unit 16 displays the image corrected by the luminance correction unit 15 on the display panel 5 as a preview screen.

S105: The accepting unit 17 further displays on the display panel 5 a screen for allowing the user to select whether or not to read the document by changing the light amount, and to select whether or not to read the document by the user's operation. Accept (request).
S106: The accepting unit 17 moves the process to S107 when receiving a request operation for changing the light amount and reading the document, and ends the process when the request for changing the light amount and reading the document is not accepted. .

  S107: When the scanner 100 determines that the number of readings of the bookbinding document 51 by the image reading unit 7 has reached a predetermined number of readings, the scanner 100 ends the process. When the scanner 100 determines that the number has not yet reached, the process proceeds to S108. Note that the predetermined number of readings is a value selected according to the required accuracy of luminance correction, and is stored in the storage unit 8.

  S108: When the accepting unit 17 accepts a request operation for changing the light amount and reading the document, the exposure adjusting unit 9 changes (increases) the light amount of the light source of the scanning unit 1 according to the requested operation, and the image reading unit 7 Reads the bookbinding document 51 placed on the table 2, acquires image information of the bookbinding document 51, and stores the image information in the storage unit 8. In this embodiment, the light source is an LED light source, and the exposure value is changed by changing the current value of the LED light source and adjusting the lighting time. The exposure amount can also be changed by changing the number of point light sources to be lit among the point light sources.

Next, referring to FIG. 13 according to the step represented by S in the flowchart showing the flow of the pixel column synthesizing process in the second embodiment of FIG. 17, the pixel column synthesizing process performed by the pixel column synthesizing unit in S102 described above. While explaining.
S201: The pixel row synthesizing unit 12 performs the processing of S202 to S207 for each pixel row 121a parallel to the longitudinal direction of the binding portion of the bookbinding original (reading marker 53) of the standard light quantity image information shown in FIG. Repeat the process.

S202: The pixel row synthesizing unit 12 counts the number of whiteout pixels for each pixel row 121a parallel to the longitudinal direction of the binding portion of the bookbinding original (reading marker 53) of the standard light quantity image information shown in FIG. N is calculated.
S203: The pixel column synthesizing unit 12 performs the processing of S204 to S206 on each image information obtained by reading the bookbinding document by changing the light amount in S108 described above, and repeats the number of times of the read image information.

S204 to S208: Since they are the same as S44 to S48 in FIG.
As described above, by performing the luminance correction processing of S101 to S108 described above, a request to perform additional document reading by a user operation is displayed after the luminance-corrected image is displayed on the display panel as a preview screen. Thus, it is possible to reflect the user's desire regarding the accuracy of luminance correction.

As described above, in the second embodiment, in addition to the effects of the first embodiment, an image whose luminance has been corrected is displayed on the display panel as a preview screen, and an additional document is read by a user operation. By accepting the request, it is possible to reflect the user's desire regarding the accuracy of luminance correction.
In the first and second embodiments, the description has been given of the example in which the position of the binding portion in the acquired image is specified by matching the binding portion of the bookbinding document to the reading mark provided on the mounting table. The position of the binding portion in the image acquired by the image processing of the scanner may be detected.

DESCRIPTION OF SYMBOLS 1 Scan part 2 Mounting stand 3 Operation button 4 Start button 5 Display panel 6 Cover 7 Image reading part 8 Memory | storage part 9, 14 Exposure adjustment part 10 White-out pixel detection part 11 Brightness difference calculation part 12 Pixel row | line | column synthetic | combination part 13, 15 Brightness Correction unit 16 Display unit 17 Reception unit 21 Light source 22 Image sensor 100 Scanner

Claims (6)

In an image processing apparatus that reads an image of a document,
An exposure adjustment unit for increasing or decreasing the amount of light from the light source;
An image reading unit that reads the image information including the luminance value of each pixel by irradiating the light of the light source adjusted by the exposure adjustment unit, and reads the image information of the document for each of the adjusted at least two light amounts; ,
A whiteout pixel detection unit that detects a whiteout pixel in which a luminance value of each pixel included in the image information read by increasing the amount of light exceeds a threshold, and detects a pixel row including the whiteout pixel;
A luminance difference calculation unit for calculating a difference between the maximum value and the minimum value of the luminance value in each pixel column of the image information;
For each pixel column, among all the read image information, a pixel column that has the largest difference between the maximum value and the minimum value of the luminance value and does not include the whiteout pixel is selected and combined. A pixel column synthesis unit for generating an intermediate image;
An image processing apparatus comprising: a luminance correction unit that performs luminance correction of the intermediate image. The image processing apparatus according to claim 1.
The original is a bound original;
The pixel row is a pixel row parallel to the longitudinal direction of the binding portion in the image information of the bookbinding document,
The whiteout pixel detection unit is configured such that, for each pixel row, the number of whiteout pixels in the image information read with the standard light quantity is the number of whiteout pixels in the image information read by increasing the light quantity from the standard light quantity. Therefore, when the number is equal to or greater than a predetermined number, the image processing apparatus determines that the pixel row in the image information read with the light amount increased is a pixel row including a whiteout pixel. The image processing apparatus according to claim 1.
The original is a bound original;
The pixel row is a pixel row parallel to the longitudinal direction of the binding portion in the image information of the bookbinding document,
The image processing apparatus, wherein the luminance difference calculation unit calculates a difference between a maximum value and a minimum value of luminance values in each pixel column. The image processing apparatus according to claim 1.
The original is a bound original;
The pixel row is a pixel row parallel to the longitudinal direction of the binding portion in the image information of the bookbinding document,
The pixel column synthesizing unit extracts, for each pixel column, a pixel column having a maximum difference between a maximum value and a minimum value from all the read image information, and combines the extracted pixel columns. And generating an intermediate image. The image processing apparatus according to claim 1.
The original is a bound original;
The pixel row is a pixel row parallel to the longitudinal direction of the binding portion in the image information of the bookbinding document,
For each pixel column of the intermediate image generated by the pixel column synthesis unit, the luminance correction unit calculates a ratio calculated so that the largest luminance value in the pixel column becomes the maximum luminance value. An image processing apparatus that normalizes the luminance value of each pixel by multiplying the luminance value of each pixel. The image processing apparatus according to claim 1.
A display unit for displaying a result of the luminance correction performed by the luminance correction unit;
A reception unit that receives a request operation for reading image information of the document,
The image processing apparatus, wherein the image reading unit reads image information of the document with the adjusted light amount according to a request operation received by the receiving unit.