JP4200779B2 - Image processing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image processing apparatus that reads an image of a document and performs processing for forming the read image.
[0002]
[Prior art]
An image forming process in an image processing apparatus such as a conventional copying machine, facsimile apparatus, scanner apparatus, or a multi-function machine having these functions is a reading operation for extracting image feature points of the entire image. It is known that the image is formed by performing a can, performing gamma correction based on the result at the time of the main scan (see, for example, Patent Document 1).
[0003]
The movement operation of the scanner head in such a pre-scan operation will be described with reference to FIG.
As shown in FIG. 17, the scanner head 3 of the image processing apparatus moves from the scanner standby position, which is the document reference position (A), toward the reference white plate 8 (arrow I), and the first shading correction position. In (B), after the first shading reference reading, the second shading correction position (C) is moved (arrow II), and the second shading reference reading is performed. Then, the scanner head 3 moves to the scanner head approach start position (D) (arrow III), and then the platen 1 so as to pre-scan the range from the document reference position (A) to the document edge position (E). Move to the side (arrow IV). Then, the scanner head 3 returns to the scanner head approach start position (D) (arrow V), and then performs a main scan (arrow VI). Then, the scanner head 3 moves to the scanner-home position sensor position (F) (arrow VII), and after adjusting the scanner head position, returns to the scanner standby position that is the document reference position (A) ( Arrow VIII).
[0004]
The image feature point of the entire original image read by the scanner head 3 during this pre-scan (arrow IV) is based on the luminance (shading data) of the reference white plate 8 read by the scanner head 3 in the two shading reference readings. Shading correction. Then, the image processing apparatus performs gamma correction set and determined from the overall image feature point during the main scan (arrow VI). Here, the reason for performing the shading reference reading twice is to increase the accuracy of the shading correction.
In addition, when setting and determining gamma correction based on the whole image feature point, gamma correction data for performing gamma correction may be calculated from a predetermined arithmetic expression, and optimal from a plurality of gamma correction data stored in advance. Gamma correction data may be selected.
[0005]
[Patent Document 1]
JP 7-336503 A
[0006]
[Problems to be solved by the invention]
However, in the case of the above-mentioned Patent Document 1, there is a problem that it takes time to read the entire image in the pre-scan and to analyze the entire read image.
For example, in the case of an image having a simple luminance distribution that is polarized between a light place and a dark place between the background density portion and the character density portion of an image original, such as a character image, the brightness in the image or for each image is increased. Since the distribution is almost the same, it is possible to estimate the image feature points (bipolar luminance distribution) of the entire image by analyzing a part of the image. There is no need to do it.
That is, such a pre-scan operation for extracting image feature points of the entire image is an effective operation for an image configured as an aggregate of various luminances such as a photographic image, but is simple. This operation is not always necessary for a character image configured as a collection of luminance, and is an inefficient operation.
[0007]
An object of the present invention is to provide an image processing apparatus that performs an efficient image reading operation and image processing of a document placed on a platen in the image processing apparatus.
[0008]
[Means for Solving the Problems]
  In order to solve the above problems, the invention described in claim 1
An image reading unit that reads an image of a document placed on a platen, and a control unit that controls the image reading unit, and the control unit performs a reading operation for extracting image feature points of the entire image of the document An image processing apparatus that controls a pre-scan, a main scan that is an entire image reading operation for performing gamma correction based on a result of the pre-scan, and a preliminary image reading that reads an image of a part of the document. And
The controller is
A luminance histogram creating means for creating a luminance histogram of the image based on an image of a part of the document read by the preliminary image reading;
Image judging means for judging whether the image of the document is a character image or a photographic image based on a brightness histogram of a part of the image of the document created by the brightness histogram creating means;
When the image determination unit determines that the image of the document is a character image, based on the brightness histogram created by the brightness histogram creation unit, selection of optimal gamma correction data or a predetermined calculation formula Gamma correction data setting means for calculating gamma correction data;
Gamma correction control means for performing gamma correction based on the gamma correction data set by the gamma correction data setting means at the time of the main scan,
When the image determination unit determines that the image of the document is a photographic image, prescanning and main scanning of the entire image of the document are performed.
[0011]
  Claim 1According to the described invention, the brightness histogram creating means creates a brightness histogram of an image in a part of the document read by the preliminary image reading, and based on the created brightness histogram, the image judging means converts the document image into a character image Or whether it is a photographic image.
  When the image judging means judges that the image of the document is a character image, the gamma correction data setting means selects gamma correction data for performing the optimum gamma correction based on the brightness histogram created by the brightness histogram creating means. Alternatively, since it is calculated and set, based on the set gamma correction data, it is possible to perform image processing for performing gamma correction during the main scan for reading the entire image of the document.
  If the image determining unit determines that the image of the document is a photographic image, a pre-scan that extracts the feature points of the entire image of the document is performed, and gamma correction based on the result of the pre-scan is performed during the main scan. be able to.
  That is, it is possible to perform precise image processing that performs pre-scanning on images that require pre-scanning such as photographic images. In addition, when the original image is a character image, the gamma correction during the main scan is performed by performing the preliminary image reading for reading the partial image of the original without performing the pre-scan for reading the entire original image. The image processing can be performed and the processing time can be shortened.
  Therefore, efficient image processing according to the image of the document can be performed.
[0012]
  Claim 2The described inventionClaim 1In the image processing apparatus described in
  The controller is
  Image selection means for selecting whether the image of the document is a character image or a photographic image;
  When a character image is selected by the image selection means,
  Controlling the preliminary image reading, the luminance histogram creation means, the gamma correction data setting means, and the gamma correction control means to operate,
  When a photographic image is selected by the image selection means, a pre-scan and a main scan of the entire image of the document are performed.
[0013]
  Claim 2According to the described invention,Claim 1Of course, it is possible to obtain the same effect as that of the invention described in 1. In particular, when a character image is selected by the image selection means, a luminance histogram of an image in a part of the document read by the preliminary image reading is obtained. The creation means creates, and based on the created brightness histogram, the gamma correction data setting means selects or calculates and sets gamma correction data for performing optimal gamma correction. Based on the data, it is possible to perform image processing for performing gamma correction during the main scan for reading the entire image of the document.
  Further, when a photographic image is selected by the image selection means, a pre-scan for extracting feature points of the entire image of the document can be performed, and gamma correction based on the result of the pre-scan can be performed during the main scan.
  That is, it is possible to select a photographic image in advance for an image that needs to be pre-scanned, such as a photographic image, and perform precise image processing for pre-scanning. Further, when the image of the document is a character image, by selecting a character image in advance and performing a preliminary image reading that reads an image of a part of the document without performing a pre-scan that reads the entire image of the document, Image processing for performing gamma correction during the main scan can be performed.
  Therefore, more efficient image processing can be performed by selecting an image of a document.
[0014]
  Claim 3The described inventionClaim 1 or claim 2In the image processing apparatus described in
  A detecting means for detecting the open / closed state of the platen cover;
  The control unit is configured to detect the image reading unit from a standby position that is a predetermined distance away from a home position where the pre-scan and the main scan are started based on detection by the detection unit that the platen cover is closed. The preliminary image reading is performed to read an image of a part of the edge of the document while moving the image to the home position.
[0015]
  Claim 3According to the described invention,Claim 1 or claim 2Of course, it is possible to obtain the same effect as that of the invention described in (1). In particular, the control unit moves the image reading unit from the predetermined standby position based on the detection that the platen cover is closed by the detection unit. Since the preliminary image reading for reading a partial image at the edge of the document is performed while moving to the position, the image reading unit can move to the pre-scan and main scan operations immediately after the preliminary image is read. Therefore, there is no waste when shifting from the preliminary image reading operation to the pre-scan or main-scan operation, and the processing operation can be made more efficient.
[0016]
For example, while the scanner head of the image reading apparatus as the image reading unit moves from a predetermined standby position to a home position so as to perform a scan (back scan) in a direction opposite to the scan direction at the time of pre-scan or main scan. Then, an image of a part of the edge of the original is read. After the preliminary image is read, the scanner head moves to a pre-scan and main scan operation that moves in a predetermined direction from the home position, so that the scanner head does not perform unnecessary operations from the preliminary image reading operation. It is possible to smoothly shift to the operation of the can and the main scan.
[0017]
  In addition, based on the detection that the document is placed on the platen and the platen cover is closed by the detection means, the preliminary image reading is performed.RunTherefore, there is no need for an operation instruction for the preliminary image reading operation, and the processing operation can be made more efficient.
[0018]
  Claim 4The described inventionClaim 3In the image processing apparatus described in
  The controller is
  After the detection means detects that the platen cover is closed, at least the detection means detects that the platen cover has been opened again based on the gamma correction data set by the gamma correction data setting means. Gamma correction data storage means for storing up to
  The main scan is performed based on the gamma correction data stored in the gamma correction data storage means.
[0019]
  Claim 4According to the described invention,Claim 3Of course, it is possible to obtain the same effect as that of the invention described in (1), in particular, after detecting that the platen cover has been closed by the detection means, the gamma correction data set by the gamma correction data setting means is at least Since it can be stored in the gamma correction data storage means until the detection means detects that the document has been opened again, it is not necessary to select gamma correction data for each document processing, and the processing operation can be made more efficient.
[0020]
  Claim 5The described inventionClaims 1-4In the image processing apparatus according to any one of the above,
  A shading reference plate having a reference color;
  A shading reference reading means for reading shading data based on the luminance of the reference color of the shading reference plate by the image reading unit;
  Shading data storage means for storing the shading data read by the shading reference reading means as first shading data;
  Correction value calculation means for calculating a luminance correction value from the second shading data read by the shading reference reading means and the first shading data stored in the shading data storage means;
  Brightness histogram correction means for correcting the brightness histogram created by the brightness histogram creation means based on the brightness correction value calculated by the correction value calculation means,
  The gamma correction data setting means selects optimal gamma correction data or calculates gamma correction data from a predetermined arithmetic expression based on the luminance histogram corrected by the luminance histogram correction means.
[0021]
  Claim 5According to the described invention,Claims 1-4Of course, it is possible to obtain the same effect as the invention described in any one of the above, and in particular, the luminance of the reference color of the shading reference plate read by the shading reference reading means by the correction value calculation means in the image processing apparatus. A luminance correction value is calculated from the second shading data based on the first shading data and the first shading data stored in the shading data storage means. Then, the luminance histogram correction unit corrects the luminance histogram created by the luminance histogram creation unit based on the luminance correction value, and the gamma correction data setting unit selects gamma correction data based on the corrected luminance histogram, Alternatively, gamma correction data is calculated using a predetermined arithmetic expression, and optimal gamma correction data is set.
[0022]
Here, the shading data is, for example, data for correcting distortion components such as sensitivity spots for each pixel included in an image signal read by a CCD unit that is a light receiving unit of an image reading unit in an image processing apparatus. is there. Since this shading data is shifted as the temperature of the CCD unit changes, it is desirable to update the shading data at every predetermined timing.
[0023]
Therefore, the image processing apparatus, for example, a brightness histogram created by correcting with the first shading data based on the brightness correction value calculated by the correction value calculation means based on the second shading data and the first shading data. Is corrected as a luminance histogram based on the second shading data, so that a luminance histogram optimum for the image corrected with the second shading data can be obtained.
[0024]
That is, the gamma correction data setting unit of the image processing apparatus selects gamma correction data based on the luminance histogram corrected so as to correspond to the second shading data by canceling the influence of the first shading data, or The gamma correction data can be calculated from a predetermined arithmetic expression, and optimal gamma correction data can be set.
Therefore, the image processing apparatus can perform image processing according to a predetermined standard without being affected by the first shading data.
[0025]
  Claim 6The described inventionClaims 1-4In the image processing apparatus according to any one of the above,
  A shading reference plate having a reference color;
  A shading reference reading means for reading shading data based on the luminance of the reference color of the shading reference plate by the image reading unit;
  Shading data storage means for storing the shading data read by the shading reference reading means as first shading data;
  Correction value calculation means for calculating a luminance correction value from the second shading data read by the shading reference reading means and the first shading data stored in the shading data storage means;
  Gamma correction data correction means for correcting gamma correction data set by the gamma correction data setting means based on the luminance correction value calculated by the correction value calculation means,
  The gamma correction control means performs gamma correction based on the gamma correction data corrected by the gamma correction data correction means.
[0026]
  Claim 6According to the described invention,Claims 1-4Of course, it is possible to obtain the same effect as that of the invention described in any one of the above, and in particular, the correction value calculation means in the image processing apparatus reads the luminance of the reference color of the shading reference plate read by the shading reference reading means. A luminance correction value is calculated from the second shading data based on the first shading data and the first shading data stored in the shading data storage means. Then, the gamma correction data correction means corrects the gamma correction data set by the gamma correction data setting means based on the brightness correction value, and the gamma correction control means performs gamma correction based on the corrected gamma correction data. carry out.
[0027]
In other words, the image processing apparatus, for example, the gamma correction data set by correcting with the first shading data based on the luminance correction value calculated by the correction value calculation means based on the second shading data and the first shading data. Is corrected as gamma correction data based on the second shading data by the gamma correction data correction means, so that the gamma correction data optimum for the image corrected by the second shading data can be obtained. Then, the gamma correction control means of the image processing apparatus can perform gamma correction based on the gamma correction data corrected so as to correspond to the second shading data after the influence of the first shading data is cancelled. it can.
Therefore, the image processing apparatus can perform image processing according to a predetermined standard without being affected by the first shading data.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS.
[First Embodiment]
FIG. 1 is a perspective view showing a state in which a platen cover of the image processing apparatus according to the first embodiment of the present invention is opened. FIG. 2 is a cross-sectional view schematically showing a document feeder provided on an image reading unit and a platen cover in the image processing apparatus. FIG. 3 is a block diagram showing a main configuration of the image processing apparatus.
[0029]
As shown in FIGS. 1 and 2, a platen 1 on which a document is placed is provided on the upper surface of the main body of the image processing apparatus 100. The image processing apparatus 100 is provided with a platen cover 2 that can be freely opened and closed. The platen cover 2 covers the platen 1 when it is closed. The platen cover 2 is provided with a document feeder 7. The document feeder 7 includes a document tray 7a, a document insertion section 7b, a document transport roller 7c, a document transport belt 7d, a belt drive roller 7e, a document discharge section 7f, The paper discharge tray 7g is configured.
[0030]
Inside the image processing apparatus 100, an image reading unit 20 that reads an image of a document placed on the platen 1 is provided on the lower side of the platen 1. The image reading unit 20 includes, for example, a scanner head 3 including an exposure lamp 3a (for example, a fluorescent lamp, a halogen lamp, etc.), a mirror 3b, and the like, and a CCD unit 4 that receives read scattered light from the scanner head 3, It consists of a mirror 5 and the like. Further, a scale plate 6 is provided on one end side of the upper surface of the platen 1, and a white reference plate 8 as a shading reference plate is provided on the lower side of the scale plate 6.
[0031]
The image reading unit 20 performs a scanning operation for reading an image of a document placed on the platen 1 in response to the scanner head 3 being moved (reciprocated) in a predetermined direction by a driving unit (not shown). This scanning operation includes, for example, a pre-scan for reading the image to check the density of the entire image of the document, a main scan for reading the entire image of the document for image formation, and a preliminary image reading to be described later. Based on the means 11, there is a preliminary image reading operation (back scan) for reading an image of a part of a document.
The white reference plate 8 is a resin plate-like member having a predetermined reference color (white) that serves as a reference for checking whether the image processing apparatus 100 performs image processing under a predetermined image reading condition. is there.
Here, the scale plate 6 side of the platen 1 is defined as a home position HP of the scanner head 3, and a position separated from the home position HP by a predetermined interval is defined as a standby position WP of the scanner head 3.
[0032]
As shown in FIG. 3, the image processing apparatus 100 includes a control unit 10 that performs overall control of the image processing apparatus 100 and performs various processes and determinations. The control unit 10 includes the above-described image. In addition to the reading unit 20, a storage unit 30, an operation unit 40, a detection unit 50, and the like are connected via a bus or the like.
[0033]
The control unit 10 temporarily stores a CPU 10a that executes arithmetic processing, various programs for various processes such as control and determination, a ROM 10b that stores various data, work areas in various processes and data generated by various processes. And a RAM 10c having a storage area for storing the data.
[0034]
The CPU 10a reads the system program and various processing programs, etc., for controlling the image processing apparatus 100 recorded and stored in the ROM 10b, into the RAM 10c, and cooperates with the read program for the entire image processing apparatus 100. Take control.
[0035]
The ROM 10b is configured by a nonvolatile semiconductor memory or the like, stores a system program corresponding to the image processing apparatus 100 and various processing programs executable on the system program, and stores these various programs. Further, the ROM 10b stores a plurality of gamma correction data GD serving as a gamma correction reference for the original image, and has a recording unit 60 for recording the gamma correction data GD.
[0036]
The RAM 10c serves as a temporary work area and storage area for programs and data read from the ROM 10b in various processes controlled by the CPU 10a. Further, the RAM 10c has gamma correction data storage means 70a for temporarily storing gamma correction data GD set by a gamma correction data setting means 13 described later.
[0037]
Such a control unit 10 performs various processes on the image of the document read by the image reading unit 20, control, determination, and the like based on operation signals, detection signals, and the like of the operation unit 40 and the detection unit 50.
In the present embodiment, the control unit 10 includes a preliminary image reading unit 11, a luminance histogram creating unit 12, a gamma realized by software processing in cooperation with the CPU 10 a and each processing program stored in the ROM 10 b. A correction data setting unit 13, a gamma correction control unit 14, an image determination unit 15 and the like are provided.
[0038]
The preliminary image reading unit 11 of the control unit 10 is configured so that the scanner head 3 of the image reading unit 20 performs the preliminary image reading operation in which the image reading unit 20 reads a part of the image corresponding to a predetermined range of the document. Operation control of a drive unit (not shown) and the image reading unit 20 is performed so as to move the range, and an image of a part of the document is read.
[0039]
Further, the luminance histogram creating means 12 of the control unit 10 creates a luminance histogram hg (HG) of the image based on the image of the original read by the image reading unit 20.
[0040]
Further, the gamma correction data setting unit 13 of the control unit 10 generates gamma correction data GD for performing optimum gamma correction on the image based on the luminance histograms hg and HG created by the luminance histogram creation unit 12. 10 is selected and set from the gamma correction data group recorded and stored in the ROM 10b (recording means 60).
[0041]
The gamma correction control unit 14 of the control unit 10 performs gamma correction during the main scan based on the gamma correction data GD selected and set by the gamma correction data setting unit 13.
[0042]
The image determination unit 15 of the control unit 10 determines whether the image is a character image based on the luminance histogram hg generated by the luminance histogram generation unit 12 from a partial image of the document read by the image reading unit 20. Determine whether it is a photographic image.
Here, the character image includes both a background type in which characters are printed on a white background and an inverted type in which characters are printed in white. In addition to monochrome photographs and color photographs, photographic images include objects other than character images, such as paintings and drawings.
[0043]
The preliminary image reading means 11, the luminance histogram creation means 12, the gamma correction data setting means 13, the gamma correction control means 14, and the image determination means 15 are based on the cooperation of the CPU 10a and each processing program stored in the ROM 10b. Although it is realized by software processing, the function of each processing program may be realized by dedicated hardware that operates under the control of the CPU 10a.
[0044]
The image reading unit 20 reads an image of a document placed on the platen 1 of the image processing apparatus 100 and shading data based on the luminance of the white reference plate 8.
The storage unit 30 is configured by, for example, an optical system / magnetic system storage medium or the like, and stores various data.
The operation unit 40 is for instructing various operations of the image processing apparatus 100, and includes, for example, an operation input key 41, a display screen 42, and the like. The operation input key 41 is configured to input settings of the image processing apparatus 100 and driving operation instructions, and is, for example, an operation button, a remote controller, or the like. The display screen 42 is configured by an LCD or the like, for example, and displays settings of the image processing apparatus 100, an operation state, and the like. When the operation unit 40 is a touch panel, the display screen 42 is configured to have operation input keys.
The detection unit 50 is configured as detection means for detecting the presence / absence of a document in the platen 1 of the image processing apparatus 100, the size of the document, and the opening / closing of the platen cover 2, and includes, for example, a photo sensor, For example, a contact switch sensor.
[0045]
Next, the operation of the image processing apparatus 100 configured as described above will be described with reference to the flowchart shown in FIG.
As shown in FIG. 4, during use of the image processing apparatus 100, the detection unit 50 detects that the platen cover 2 of the image processing apparatus 100 is closed, and detects that the platen cover 2 is closed from the detection unit 50. When the signal shown is input to the control unit 10 (step S101; Yes), the process proceeds to step S102. Next, the detection unit 50 detects that a document is placed on the platen 1 of the image processing apparatus 100, and a signal indicating that the document is placed on the platen 1 from the detection unit 50 is sent to the control unit 10. When input (step S102; Yes), the detection unit 50 detects the size of the document and inputs a signal indicating the size of the document to the control unit 10 (step S103). On the other hand, when a signal indicating that no document is placed on the platen 1 is input from the detection unit 50 to the control unit 10 (step S102; No), the process returns to step S101.
[0046]
Next, the preliminary image reading unit 11 of the control unit 10 moves the scanner head 3 of the image reading unit 20 from the predetermined standby position WP (for example, the standby position WP shown in FIGS. 1 and 2) to the home position HP that is the scan start position. (For example, while moving to the home position HP shown in FIGS. 1 and 2), a preliminary image reading operation is performed to read an image of a part of the document edge in the document main scanning direction width based on the detected document size (step). S104). Next, the luminance histogram creating means 12 of the control unit 10 creates a luminance histogram hg of an image of a part of the document edge based on the document image read by the image reading unit 20 (step S105). Next, the image determination unit 15 of the control unit 10 determines whether the image is a character image or a photographic image based on the created luminance histogram hg (step S106).
[0047]
Here, the determination of whether the read image of the original document is a character image or a photographic image performed in step S106 will be described in detail. For example, the luminance histogram hg shown in FIG. 5A schematically shows a luminance histogram hg of a normal character document (a dark (dark) color character on a light background document). The luminance histogram hg shown in b) schematically shows the luminance histogram hg of a photographic document. The operation of determining what kind of original the brightness histogram hg is will be described with reference to the flowchart shown in FIG.
First, the luminance frequency maximum value (Hmax) in the luminance histogram hg and the threshold value L.P. H. Comparison with (Limit H) is performed (step S1). Hmax is a threshold value L.P. H. If it is determined to be smaller (lower) (step S1; No), the luminance histogram hg is determined to be an image of another type (photo original). On the other hand, Hmax is a threshold value L.P. H. When it is determined that it is larger (higher) (step S1; Yes), the process proceeds to step S2.
Next, the maximum luminance value (Imax) corresponding to the maximum frequency value (Hmax) in the luminance histogram hg, and the threshold value L.P. I. Comparison with (Limit I) is performed (step S2). Imax is a threshold L.I. I. If it is determined that it is larger (higher) (step S2; Yes), the luminance histogram hg is determined to be a background image (normal character original). On the other hand, Imax is a threshold value L.P. I. If it is determined to be smaller (lower) (step S2; No), the luminance histogram hg is determined to be an inverted image (black / dark color background with white text original).
[0048]
As described above, the frequency maximum value (Hmax) in the luminance histogram hg and the threshold value L.P. H. And the maximum luminance value (Imax) and the threshold value L. I. Based on the comparison, the type, state, etc. of the image of the luminance histogram hg can be determined. It should be noted that by increasing the determination criteria such as the threshold value, it is possible to make a more detailed determination of various image types and states.
[0049]
Next, when the control unit 10 determines that the read document image is a character image (step S106; character), the gamma correction data setting unit 13 of the control unit 10 is based on the luminance histogram hg created in step S105. Then, the gamma correction data GD for performing the optimum gamma correction for the image is selected from the ROM 10b (recording means 60) of the control unit 10, and the gamma correction data is stored in the RAM 10c (gamma correction data storage means 70a) of the control unit 10. The correction data GD is stored (step S107). Then, the gamma correction control means 14 of the control unit 10 performs gamma correction based on the gamma correction data GD selected and stored together with the main scan for reading the entire image of the document (step S108), and performs image formation processing (step S108). Step S109).
Next, the control unit 10 determines whether or not the platen cover 2 has been opened (step S110). When the signal indicating that the platen cover 2 has been opened is not input to the control unit 10 (step S110; No), the process waits repeatedly until the signal indicating that the platen cover 2 has been opened is input. On the other hand, when a signal indicating that the platen cover 2 has been opened is input from the detection unit 50 to the control unit 10 (step S110; Yes), the storage of the gamma correction data GD stored in the RAM 10c of the control unit 10 is erased. (Step S111), the process is terminated.
[0050]
On the other hand, when the control unit 10 determines that the read image of the document is a photographic image (step S106; photograph), the control unit 10 determines the image reading unit 20 based on the document size detection signal of the detection unit 50. A pre-scan for reading the entire image of the original is performed (step S112), and the luminance histogram creating means 12 of the control unit 10 is based on the image of the original read by the image reading unit 20, and the entire luminance histogram HG of the entire original image of the original. Is created (step S113). Then, the gamma correction data setting means 13 of the control unit 10 obtains gamma correction data GD for performing optimum gamma correction for the image from the ROM 10b (recording means 60) based on the whole luminance histogram HG created in step S113. At the same time, the gamma correction data GD is stored in the RAM 10c (gamma correction data storage means 70a) (step S114). Then, the gamma correction control means 14 of the control unit 10 performs gamma correction based on the gamma correction data GD selected and stored together with the main scan for reading the entire image of the document (step S115), and performs image forming processing (step S115). Step S116).
[0051]
Next, the control unit 10 determines whether or not the platen cover 2 has been opened (step S117). When a signal indicating that the platen cover 2 is opened is not input to the control unit 10 (step S117; No), the process is on standby until a signal indicating that the platen cover 2 is opened is input. On the other hand, when a signal indicating that the platen cover 2 has been opened is input from the detection unit 50 to the control unit 10 (step S117; Yes), the storage of the gamma correction data GD stored in the RAM 10c of the control unit 10 is deleted. (Step S118), and this process is terminated.
[0052]
Here, selection of the gamma correction data GD for performing optimal gamma correction on the image from the ROM 10b (recording means 60) of the control unit 10 based on the luminance histogram hg and the overall luminance histogram HG will be described in detail. For example, FIG. 7 shows luminance histograms hg and HG of a background image (normal character original) and gamma correction data GD corresponding to the luminance histograms hg and HG. FIG. 8 shows luminance histograms hg and HG of an inverted image (black / dark colored background original) and gamma correction data GD corresponding to the luminance histograms hg and HG. FIG. 9 shows brightness histograms hg and HG of other types of images (photo originals) and gamma correction data GD corresponding to the brightness histograms hg and HG.
[0053]
As described above, the maximum frequency value (Hmax), maximum luminance value (Imax), brightest value (Ilight), darkest value (Idark), peak value (Iridge), peak value (Hridge) in the luminance histograms hg and HG. ), Etc., and a plurality of gamma correction data GD corresponding to the brightness histograms hg, HG curve states, etc. are set and recorded in the recording means 60 of the ROM 10b of the control unit 10. Then, according to the control processing program, the control unit 10 selects gamma correction data GD determined to be optimal for the luminance histogram hg and the overall luminance histogram HG of the image from the ROM 10b (recording means 60) of the control unit 10, and the gamma correction data. Gamma correction based on the correction data GD is performed.
[0054]
As described above, in the image processing apparatus 100, based on the luminance histogram hg of the image of a part of the document edge read by the image reading unit 20, it is determined whether the image is a character image or a photographic image. Therefore, in the case of a photographic image that requires analysis of the entire image, control for performing image processing for pre-scanning the entire image can be performed. In the case of a character image that does not require pre-scanning of the entire image, gamma correction can be performed based on the luminance histogram hg of a partial image at the edge of the document read by the image reading unit 20, so that the image processing time Can be shortened. Therefore, automatic image processing according to the image of the document can be performed.
[0055]
[Second Embodiment]
Next, a second embodiment of the present invention will be described. In addition, the same code | symbol is attached | subjected to the same part as 1st Embodiment, and only a different part is demonstrated.
In the image processing apparatus, for example, when it is determined to perform image processing on a photographic document, it is not necessary to determine whether the photographic document is a character image or a photographic image. That is, when image processing of a photographic document is selected in advance, a preliminary image is read from the document, a luminance histogram hg is created, and a pre-scan operation is performed without determining whether the image is a character image or a photographic image. Therefore, the processing time can be shortened.
[0056]
As shown in FIG. 10, the operation unit 40 in the image processing apparatus 200 includes image selection means 41 that can select an image mode (for example, a photo mode, a character mode, etc.). Specifically, for example, the image processing apparatus 200 selects, as the image selection unit 41, a photo mode key for selecting and inputting image processing in the photo mode, or performing image processing in the character mode. It has character mode keys for selecting and entering. When those keys that are the image selection means 41 are pressed, a press signal indicating that the key has been pressed is output, and the press signal indicating the image mode selected via the image selection means 41 is transmitted to the control unit. 10 is sent.
[0057]
Then, the control unit 10 performs image processing according to the image mode based on the image mode selected by the image selection unit 41 of the operation unit 40. Specifically, the operation of the image processing apparatus 200 will be described along the flowchart shown in FIG.
As shown in FIG. 11, during use of the image forming apparatus 100, the detection unit 50 detects that the platen cover 2 of the image processing apparatus 200 is closed, and the detection unit 50 detects that the platen cover 2 is closed. When the signal shown is input to the control unit 10 (step S201; Yes), the process proceeds to step S202. Next, the detection unit 50 detects that a document is placed on the platen 1 of the image processing apparatus 200, and a signal indicating that the document is placed on the platen 1 from the detection unit 50 is sent to the control unit 10. When input (step S202; Yes), the detection unit 50 detects the size of the document and inputs a signal indicating the size of the document to the control unit 10 (step S203). On the other hand, when a signal indicating that a document is not placed on the platen 1 is input from the detection unit 50 to the control unit 10 (step S202; No), the process returns to step S201.
[0058]
Next, the control unit 10 determines which image mode (for example, photo mode, character mode) is selected (step S204). When the control unit 10 detects a signal indicating that the photo mode is selected from the image selection unit 41 of the operation unit 40 (step S204; photo mode), the control unit 10 performs a pre-scan to read the entire image of the document. (Step S205) The brightness histogram creating means 12 of the control unit 10 creates an overall brightness histogram HG of the entire image of the document based on the image of the document read by the image reading unit 20 (Step S206). Then, the gamma correction data setting unit 13 of the control unit 10 performs gamma correction for performing optimal gamma correction on the image from the ROM 10b (recording unit 60) of the control unit 10 based on the overall luminance histogram HG created in step S206. The correction data GD is selected, and the gamma correction data GD is stored in the RAM 10c (gamma correction data storage means 70a) of the control unit 10 (step S207). Then, the gamma correction control means 14 of the control unit 10 performs gamma correction based on the gamma correction data GD selected and stored together with the main scan for reading the entire image of the document (step S208), and performs image formation processing (step S208). Step S209).
[0059]
Next, the control unit 10 determines whether or not the platen cover 2 has been opened (step S210). When the signal indicating that the platen cover 2 is opened is not input to the control unit 10 (step S210; No), the process waits until the signal indicating that the platen cover 2 is opened is input. On the other hand, when a signal indicating that the platen cover 2 is opened is input from the detection unit 50 to the control unit 10 (step S210; Yes), the storage of the gamma correction data GD stored in the RAM 10c of the control unit 10 is deleted. (Step S211), the process is terminated.
[0060]
On the other hand, when the control unit 10 detects a signal indicating that the character mode has been selected from the operation unit 40 (step S204; character mode), the preliminary image reading unit 11 of the control unit 10 causes the scanner head of the image reading unit 20 to scan. 3 is moved from a predetermined standby position WP (for example, the standby position WP shown in FIGS. 1 and 2) to the home position HP (for example, the home position HP shown in FIGS. 1 and 2) that is a scan start position. Based on the size of the original document, a preliminary image reading operation is performed to read an image of a part of the original edge portion in the width of the original main scanning direction (step S212). Next, the luminance histogram creating means 12 of the control unit 10 creates a luminance histogram hg of an image of a part of the document edge based on the document image read by the image reading unit 20 (step S213). Next, the gamma correction data setting unit 13 of the control unit 10 performs gamma correction for performing optimal gamma correction on the image from the ROM 10b (recording unit 60) of the control unit 10 based on the luminance histogram hg created in step S213. The data GD is selected, and the gamma correction data GD is stored in the RAM 10c (gamma correction data storage means 70a) of the control unit 10 (step S214). Then, the gamma correction control means 14 of the control unit 10 performs gamma correction based on the gamma correction data GD selected and stored together with the main scan for reading the entire image of the document (step S215), and performs image formation processing (step S215). Step S216).
[0061]
Next, the control unit 10 determines whether or not the platen cover 2 has been opened (step S217). When the signal indicating that the platen cover 2 is opened is not input to the control unit 10 (step S217; No), the process is on standby until the signal indicating that the platen cover 2 is opened is input. On the other hand, when a signal indicating that the platen cover 2 has been opened is input from the detection unit 50 to the control unit 10 (step S217; Yes), the gamma correction data GD stored in the RAM of the control unit 10 is erased. (Step S218), the process is terminated.
[0062]
As described above, in the image processing apparatus 200, an image mode corresponding to an image of a document to be image-processed, for example, a photo mode, a character mode, and the like is selected and input in advance by the operation unit 40, whereby the image of the document is processed. Can be performed. Therefore, it is not necessary to determine whether the image of the document is a photographic image or a character image, image processing based on the selected image mode can be performed, and processing time can be shortened.
[0063]
[Third Embodiment]
Next, a third embodiment of the present invention will be described. In addition, the same code | symbol is attached | subjected to the same part as 1st, 2nd embodiment, and only a different part is demonstrated.
[0064]
The image reading unit 20 (scanner head 3) of the image processing apparatus 300 performs a shading reference reading operation for reading shading data based on the luminance of the white reference plate 8 based on a shading reference reading unit 16 described later.
[0065]
The operation unit 40 in the image processing apparatus 300 may include an operation unit capable of selecting an image forming speed adjustment mode (for example, a Fast mode, a Fine mode, etc.). Specifically, for example, the operation unit 40 of the image processing apparatus 300 uses the Fast mode key for selecting image formation in the Fast mode in which image formation is performed faster as the image formation speed adjustment unit, There is a Fine mode key for selecting to perform image formation in the Fine mode for performing image formation. When those keys that are image forming speed adjusting means are pressed, a pressing signal indicating that the key has been pressed is output, and the pressing signal indicating the selected image forming speed adjusting mode is sent to the control unit 10. It is done.
[0066]
As shown in FIG. 12, the control unit 10 further includes a shading reference reading unit 16, a correction value calculating unit 17, and a luminance histogram correcting unit 18.
[0067]
The shading reference reading unit 16 of the control unit 10 is a scanner of the image reading unit 20 for performing a shading reference reading operation in which the image reading unit 20 reads shading data based on the luminance (density) of the reference color of the white reference plate 8. Operation control of a drive unit and an image reading unit 20 (not shown) is performed so that the head 3 moves to the position of the white reference plate 8, and the luminance (shading data) of the white reference plate 8 is read.
[0068]
The correction value calculation means 17 of the control unit 10 compares the second shading data read by the shading reference reading means 16 with the first shading data stored in the shading data storage means 70b described later, A brightness correction value is calculated based on the difference, ratio, and the like.
[0069]
The luminance histogram correction unit 18 of the control unit 10 corrects the luminance histogram created by the luminance histogram creation unit 12 based on the luminance correction value calculated by the correction value calculation unit 17.
[0070]
The RAM 10c of the control unit 10 of the image processing apparatus 300 has a function of storing document image data read by the image reading unit 20 and luminance (density) data of the white reference plate 8. In particular, the RAM 10c includes a shading data storage unit 70b, and stores the shading data (first shading data) based on the luminance of the reference color of the white reference plate 8 read by the shading reference reading unit 16 of the control unit 10. Have
[0071]
In the present embodiment, the shading reference reading unit 16, the correction value calculation unit 17, and the luminance histogram correction unit 18 are realized by software processing in cooperation with the CPU 10a and each processing program stored in the ROM 10b. The The function of each processing program may be realized by dedicated hardware that operates under the control of the CPU 10a.
[0072]
Next, the operation of the image processing apparatus 300 according to the third embodiment of the present invention will be described with reference to the flowchart shown in FIG.
As illustrated in FIG. 13, during use of the image forming apparatus 300, the detection unit 50 detects that the platen cover 2 of the image processing apparatus 300 is closed, and the detection unit 50 detects that the platen cover 2 is closed. When the signal shown is input to the control unit 10 (step S301; Yes), the process proceeds to step S302. Next, the detection unit 50 detects that a document is placed on the platen 1 of the image processing apparatus 300, and a signal indicating that the document is placed on the platen 1 from the detection unit 50 is sent to the control unit 10. When input (step S302; Yes), the detection unit 50 detects the size of the document and inputs a signal indicating the size of the document to the control unit 10 (step S303). On the other hand, when a signal indicating that no document is placed on the platen 1 is input from the detection unit 50 to the control unit 10 (step S302; No), the process returns to step S301.
[0073]
Next, the control unit 10 determines which image forming speed adjustment mode (for example, Fast mode, Fine mode) is selected (step S304). When the control unit 10 detects a signal indicating that the Fast mode for faster image formation is selected from the operation unit 40 (step S304; Fast mode), the preliminary image reading unit 11 of the control unit 10 reads the image reading unit. 20 scanner heads 3 are moved from a predetermined standby position WP (for example, the standby position WP shown in FIGS. 1 and 2) to a home position HP (for example, the home position HP shown in FIGS. 1 and 2) as a scan start position. Then, a preliminary image reading operation is performed to read an image of a part of the document edge based on the detected document size based on the first shading data stored in the shading data storage unit 70b in the document main scanning direction width. The read image data is stored in the RAM 10c of the control unit 10 (step S305). Next, the luminance histogram creating means 12 of the control unit 10 creates a luminance histogram of the image based on the document image data stored in the RAM 10c in step S305, and temporarily stores it in the RAM 10c (step S306). Note that the creation of the luminance histogram may be performed with dedicated hardware.
[0074]
Next, the shading reference reading unit 16 of the control unit 10 moves the scanner head 3 of the image reading unit 20 to a predetermined shading correction position (B, C), and obtains second shading data based on the luminance of the white reference plate 8. A reading shading reference reading operation is performed (step S307).
Next, in step S307, the correction value calculation unit 17 of the control unit 10 reads the second shading data of the white reference plate 8 read by the image reading unit 20 based on the shading reference reading unit 16, and the shading data storage unit 70b of the RAM 10c. The brightness correction value is calculated based on the first shading data stored in. Then, the read second shading data and brightness correction value of the white reference plate 8 are stored in the RAM 10c of the control unit 10 (step S308). Here, the second shading data stored in the RAM 10c (shading data storage means 70b) is the first shading data for the next operation.
[0075]
Next, the luminance histogram correction means 18 of the control unit 10 corrects the luminance histogram stored in the RAM 10c in step S306 based on the luminance correction value calculated in step S308 (step S309).
Then, the gamma correction data setting unit 13 of the control unit 10 selects gamma correction data GD for performing optimal gamma correction for the image from the ROM 10b (recording unit 60) based on the luminance histogram corrected in step S309. At the same time, the gamma correction data GD is stored in the RAM 10c (gamma correction data storage means 70a) (step S310). Then, the gamma correction control unit 14 of the control unit 10 selects and stores the gamma correction that is selected and stored together with the main scan for reading the entire image of the document based on the second shading data read by the shading reference reading unit 16 in step S307. Gamma correction based on the data GD is performed (step S311), and image forming processing is performed (step S312).
[0076]
Here, the moving operation of the scanner head 3 from step S305 to step S311 will be described with reference to FIG.
As shown in FIG. 14, when the scanner head 3 of the image processing apparatus moves from the predetermined standby position WP (a) toward the reference white plate 8 (arrow i), the scanner head 3 moves from the standby position WP (a). Preliminary image reading (back scanning) is performed in a direction opposite to the main scanning direction in a part of the original image area up to the original reference position (A). (S305)
Based on the read image data of the document, a brightness histogram of the image is created. (S306)
Next, the scanner head 3 performs a shading reference reading at two shading correction positions (C, B). (S307) Here, in order to increase the accuracy of the shading correction, reading is performed at two locations and the shading data is obtained from both data. However, reading at one location may be possible.
Then, the scanner head 3 moves to the scanner head run start position (D) (arrow iii). For example, during this movement, the brightness correction value corresponding to steps S308, S309, and S310, brightness histogram correction, gamma correction data selection, and the like are performed.
Next, the scanner head 3 moves in the main scanning direction in the range from the document reference position (A) to the document edge position (E) (arrow iv). (S311) Then, the scanner head 3 moves to the scanner-home position sensor position (F) (arrow v), and after the scanner head position is adjusted, returns to the standby position WP (a) (arrow vi). ).
[0077]
Next, the control unit 10 determines whether or not the platen cover 2 has been opened (step S313). If the signal indicating that the platen cover 2 has been opened is not input to the control unit 10 (step S313; No), the process waits until a signal indicating that the platen cover 2 has been opened is input. On the other hand, when a signal indicating that the platen cover 2 is opened is input from the detection unit 50 to the control unit 10 (step S313; Yes), the storage of the gamma correction data GD stored in the RAM 10c of the control unit 10 is deleted. (Step S314), and this process is terminated.
[0078]
On the other hand, when the control unit 10 detects a signal indicating that the Fine mode for forming a higher quality image is selected from the operation unit 40 (Step S304; Fine mode), the shading reference reading unit 16 of the control unit 10 Then, the scanner head 3 of the image reading unit 20 is moved to a predetermined shading correction position to perform a shading reference reading operation for reading shading data based on the luminance of the white reference plate 8, and the control unit 10 stores the read shading data in the RAM 10c. Store (step S315).
[0079]
Next, the control unit 10 performs pre-scanning based on the shading data read by the shading reference reading unit 16 based on the shading data read by the image reading unit 20 based on the document size detection signal from the detection unit 50 (step S316). The brightness histogram creating means 12 of the control unit 10 creates a brightness histogram HG of the entire image of the document based on the image of the document read by the image reading unit 20 (step S317).
Then, the gamma correction data setting unit 13 of the control unit 10 selects gamma correction data GD for performing optimal gamma correction for the image from the ROM 10b (recording unit 60) based on the luminance histogram created in step S317. At the same time, the gamma correction data GD is stored in the RAM 10c (gamma correction data storage means 70a) (step S318). Then, the gamma correction control means 14 of the control unit 10 performs gamma correction based on the gamma correction data GD selected and stored together with the main scan for reading the entire image of the document (step S319), and performs image formation processing (step S319). Step S320).
[0080]
Next, the control unit 10 determines whether or not the platen cover 2 has been opened (step S321). When the signal indicating that the platen cover 2 is opened is not input to the control unit 10 (step S321; No), the process waits until the signal indicating that the platen cover 2 is opened is input. On the other hand, when a signal indicating that the platen cover 2 is opened is input from the detection unit 50 to the control unit 10 (step S321; Yes), the storage of the gamma correction data GD stored in the RAM of the control unit 10 is deleted. (Step S322), and this process is terminated.
[0081]
As described above, the image processing apparatus 300 uses the luminance correction value calculated by the luminance histogram correction unit based on the second shading data and the first shading data, as the luminance histogram created based on the first shading data. The luminance histogram can be corrected based on the second shading data.
The gamma correction data setting means 13 can select the gamma correction data from the recording means 16 based on the luminance histogram corrected so as to correspond to the second shading data, and therefore based on the second shading data. It is possible to set the optimal gamma correction data for the scanned image. Therefore, the image processing apparatus 300 can perform more stable image processing and image formation.
[0082]
Note that, based on the luminance histogram corrected in step S309 in the operation of the image processing apparatus 300 according to the third embodiment, as in step S106 in the operation of the image processing apparatus 100 according to the first embodiment. It may be determined whether the image of the document is a character image or a photographic image, and the scanning operation in each case may be performed.
[0083]
[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described. In addition, the same code | symbol is attached | subjected to the same part as 1st-3rd embodiment, and only a different part is demonstrated.
[0084]
The image reading unit 20 (scanner head 3) of the image processing apparatus 400 performs a shading reference reading operation for reading shading data based on the luminance of the white reference plate 8, based on the shading reference reading unit 16 of the control unit 10.
[0085]
The operation unit 40 in the image processing apparatus 400 may include an operation unit capable of selecting an image forming speed adjustment mode (for example, a Fast mode, a Fine mode, etc.). Specifically, for example, the operation unit 40 of the image processing apparatus 400 uses the Fast mode key for selecting image formation in the Fast mode in which image formation is performed faster as the image formation speed adjustment unit, or high image quality. There is a Fine mode key for selecting to perform image formation in the Fine mode for performing image formation. When those keys that are image forming speed adjusting means are pressed, a pressing signal indicating that the key has been pressed is output, and the pressing signal indicating the selected image forming speed adjusting mode is sent to the control unit 10. It is done.
[0086]
As shown in FIG. 15, the control unit 10 further includes a shading reference reading unit 16, a correction value calculation unit 17, and a gamma correction data correction unit 19.
The gamma correction data correction unit 19 of the control unit 10 corrects the gamma correction data selected by the gamma correction data setting unit 13 based on the luminance correction value calculated by the correction value calculation unit 17.
In the present embodiment, the gamma correction data correction means 19 is realized by software processing in cooperation with the CPU 10a and each processing program stored in the ROM 10b. The function of each processing program may be realized by dedicated hardware that operates under the control of the CPU 10a.
[0087]
The RAM 10 c of the control unit 10 of the image processing apparatus 400 has a function of storing document image data read by the image reading unit 20 and luminance (density) data of the white reference plate 8. In particular, the RAM 10c includes a shading data storage unit 70b, and stores the shading data (first shading data) based on the luminance of the reference color of the white reference plate 8 read by the shading reference reading unit 16 of the control unit 10. Have
[0088]
Next, the operation of the image processing apparatus 400 according to the fourth embodiment of the present invention will be described with reference to the flowchart shown in FIG.
As illustrated in FIG. 16, during use of the image forming apparatus 400, the detection unit 50 detects that the platen cover 2 of the image processing apparatus 400 is closed, and the detection unit 50 detects that the platen cover 2 is closed. When the signal shown is input to the control unit 10 (step S401; Yes), the process proceeds to step S402. Next, the detection unit 50 detects that a document is placed on the platen 1 of the image processing apparatus 400, and a signal indicating that the document is placed on the platen 1 from the detection unit 50 is sent to the control unit 10. When input (step S402; Yes), the detection unit 50 detects the size of the document and inputs a signal indicating the size of the document to the control unit 10 (step S403). On the other hand, when a signal indicating that a document is not placed on the platen 1 is input from the detection unit 50 to the control unit 10 (step S402; No), the process returns to step S401.
[0089]
Next, the control unit 10 determines which image forming speed adjustment mode (for example, Fast mode, Fine mode) is selected (Step S404). When the control unit 10 detects a signal indicating that the Fast mode for faster image formation has been selected from the operation unit 40 (step S404; Fast mode), the preliminary image reading unit 11 of the control unit 10 reads the image reading unit. 20 scanner heads 3 are moved from a predetermined standby position WP (for example, the standby position WP shown in FIGS. 1 and 2) to a home position HP (for example, the home position HP shown in FIGS. 1 and 2) as a scan start position. Then, a preliminary image reading operation is performed to read an image of a part of the document edge based on the detected document size based on the first shading data stored in the shading data storage unit 70b in the document main scanning direction width. The read image data is stored in the RAM 10c of the control unit 10 (step S405). Next, the luminance histogram creating means 12 of the control unit 10 creates a luminance histogram of the image based on the document image data stored in the RAM 10c in step S405, and temporarily stores it in the RAM 10c (step S406). Note that the creation of the luminance histogram may be performed with dedicated hardware.
[0090]
Next, the shading reference reading unit 16 of the control unit 10 moves the scanner head 3 of the image reading unit 20 to a predetermined shading correction position (B, C), and obtains second shading data based on the luminance of the white reference plate 8. A reading shading reference reading operation is performed (step S407).
Next, in step S407, the correction value calculation unit 17 of the control unit 10 reads the second shading data of the white reference plate 8 read by the image reading unit 20 based on the shading reference reading unit 16, and the shading data storage unit 70b of the RAM 10c. The brightness correction value is calculated based on the first shading data stored in. Then, the read second shading data and brightness correction value of the white reference plate 8 are stored in the RAM 10c of the control unit 10 (step S408). Here, the second shading data stored in the RAM 10c (shading data storage means 70b) is the first shading data for the next operation.
[0091]
Next, the gamma correction data setting unit 13 of the control unit 10 generates gamma correction data for performing optimum gamma correction on the image from the ROM 10b (recording unit 60) based on the luminance histogram created and stored in step S406. GD is selected (step S409). Then, the gamma correction data correction unit 19 of the control unit 10 corrects the gamma correction data GD selected in step S409 based on the luminance correction value calculated in step S408, and the corrected gamma correction data is stored in the RAM 10c. The data is stored in (gamma correction data storage means 70a) (step S410).
Then, the gamma correction control means 14 of the control unit 10 performs the gamma correction in the selection step S410 together with the main scan for reading the entire image of the document based on the second shading data read by the shading reference reading means 16 in step S407. Gamma correction based on the correction data is performed (step S411), and image forming processing is performed (step S412).
[0092]
Here, the moving operation of the scanner head 3 from step S405 to step S411 will be described with reference to FIG.
As shown in FIG. 14, when the scanner head 3 of the image processing apparatus moves from the predetermined standby position WP (a) toward the reference white plate 8 (arrow i), the scanner head 3 moves from the standby position WP (a). Preliminary image reading (back scanning) is performed in a direction opposite to the main scanning direction in a part of the original image area up to the original reference position (A). (S405)
Based on the read image data of the document, a brightness histogram of the image is created. (S406)
Next, the scanner head 3 performs a shading reference reading at two shading correction positions (C, B). (S407) Here, in order to increase the accuracy of the shading correction, reading is performed at two locations and the shading data is obtained from both data. However, reading at one location may be performed.
Then, the scanner head 3 moves to the scanner head run start position (D) (arrow iii). For example, during this movement, calculation of luminance correction values corresponding to steps S408, S409, and S410, selection of gamma correction data, correction of gamma correction data, and the like are performed.
Next, the scanner head 3 moves in the main scanning direction in the range from the document reference position (A) to the document edge position (E) (arrow iv). (S411) The scanner head 3 moves to the scanner-home position sensor position (F) (arrow v), and after the scanner head position is adjusted, returns to the standby position WP (a) (arrow vi). ).
[0093]
Next, the control unit 10 determines whether or not the platen cover 2 has been opened (step S413). When a signal indicating that the platen cover 2 is opened is not input to the control unit 10 (step S413; No), the process is on standby until a signal indicating that the platen cover 2 is opened is input. On the other hand, when a signal indicating that the platen cover 2 is opened is input from the detection unit 50 to the control unit 10 (step S413; Yes), the storage of the gamma correction data GD stored in the RAM 10c of the control unit 10 is deleted. (Step S414), and this process is terminated.
[0094]
On the other hand, when the control unit 10 detects a signal indicating that the Fine mode for forming a higher quality image is selected from the operation unit 40 (Step S404; Fine mode), the shading reference reading unit 16 of the control unit 10 Then, the scanner head 3 of the image reading unit 20 is moved to a predetermined shading correction position to perform a shading reference reading operation for reading shading data based on the luminance of the white reference plate 8, and the control unit 10 stores the read shading data in the RAM 10c. Store (step S415).
[0095]
Next, the control unit 10 performs a pre-scan based on the shading data read by the shading reference reading unit 16 based on the shading data read by the image reading unit 20 based on the document size detection signal from the detection unit 50 (step S416). The brightness histogram creating means 12 of the control unit 10 creates a brightness histogram HG of the entire image of the document based on the image of the document read by the image reading unit 20 (step S417).
Next, the gamma correction data setting unit 13 of the control unit 10 selects gamma correction data GD for performing optimal gamma correction for the image from the ROM 10b (recording unit 60) based on the luminance histogram created in step S417. At the same time, the gamma correction data GD is stored in the RAM 10c (gamma correction data storage means 70a) (step S418). Then, the gamma correction control means 14 of the control unit 10 performs gamma correction based on the gamma correction data GD selected and stored together with the main scan for reading the entire image of the document (step S419), and performs image formation processing (step S419). Step S420).
[0096]
Next, the control unit 10 determines whether or not the platen cover 2 has been opened (step S421). When the signal indicating that the platen cover 2 is opened is not input to the control unit 10 (step S421; No), the process waits until the signal indicating that the platen cover 2 is opened is input. On the other hand, when a signal indicating that the platen cover 2 has been opened is input from the detection unit 50 to the control unit 10 (step S421; Yes), the gamma correction data GD stored in the RAM of the control unit 10 is erased. (Step S422), this process is terminated.
[0097]
As described above, the image processing apparatus 400 converts the gamma correction data selected based on the first shading data to the luminance correction calculated by the gamma correction data correction unit based on the second shading data and the first shading data. The value can be corrected as gamma correction data based on the second shading data.
The gamma correction control means 14 can perform gamma correction based on the gamma correction data corrected so as to correspond to the second shading data, so that the main scan is performed based on the second shading data. Optimal gamma correction can be performed on images. Therefore, the image processing apparatus 400 can perform more stable image processing and image formation.
[0098]
In the above embodiment, the control operation and processing of the image processing apparatus (100, 200, 300, 400) have been described individually as the first to fourth embodiments. Control operation processing combined with processing, for example, image mode automatic selection processing (first embodiment), image mode manual selection processing (second embodiment), image formation speed adjustment processing (third, fourth, and so on). The above embodiment) may be performed as a series of operations, and image formation may be performed by selectively using each of these processes depending on circumstances.
[0099]
In the present embodiment, the gamma correction data setting unit 13 of the control unit 10 is based on the luminance histogram created by the luminance histogram creating unit 12 and performs gamma correction for performing optimal gamma correction on the image. The data is selected and set from the gamma correction data group recorded and stored in the ROM 10b (recording means 60) of the control unit 10, but the present invention is not limited to this, and the gamma correction data setting is performed. The means 13 may calculate and set the gamma correction data based on the brightness histogram created by the brightness histogram creation means 12 by a predetermined arithmetic expression recorded in the ROM 10b of the control unit 10.
[0100]
In the third and fourth embodiments, when the image processing device (300, 400) is activated, the image processing device first reads shading data based on the luminance of the white reference plate 8 to obtain the first shading. It is desirable to store the data in the shading data storage means 70b of the RAM 10c.
[0101]
The standby position WP of the scanner head 3 of the image reading unit 20 may be a position where a part of the image of the document can be read to such an extent that the type of image can be determined. It is preferable that correspondence is possible. For example, if the type of image can be determined by reading the end 40 mm of the document, the position 40 mm away from the home position HP is the standby position WP of the scanner head 3.
[0102]
Further, the erasure of the gamma correction data GD stored in the RAM 10c of the control unit 10 is not limited to the detection of the operation of opening the platen cover 2, but may be an erasure operation performed by the operation unit 40, for example.
[0103]
The image mode is not limited to the photo mode and the character mode, and may be any image mode such as a painting mode, a color mode, a monochrome mode, a high image quality mode, a draft mode, and the like, and is suitable for the image mode. Image processing control may be performed.
[0104]
The gamma correction data GD is composed of a plurality of gamma correction values, and the configuration is arbitrary such as a gamma correction table.
In addition, the configuration of the image reading unit 20 and the document feeder 7 is arbitrary, and it is needless to say that other specific detailed structures can be appropriately changed.
[0105]
【The invention's effect】
  According to invention of Claim 1,The luminance histogram creation means creates a luminance histogram of an image of a part of the original read by reading the preliminary image, and based on the created luminance histogram, the image determination means determines whether the original image is a character image or a photographic image. Judge whether there is.
When the image judging means judges that the image of the document is a character image, the gamma correction data setting means selects gamma correction data for performing the optimum gamma correction based on the brightness histogram created by the brightness histogram creating means. Alternatively, since it is calculated and set, based on the set gamma correction data, it is possible to perform image processing for performing gamma correction during the main scan for reading the entire image of the document.
If the image determining unit determines that the image of the document is a photographic image, a pre-scan that extracts the feature points of the entire image of the document is performed, and gamma correction based on the result of the pre-scan is performed during the main scan. be able to.
That is, it is possible to perform precise image processing that performs pre-scanning on images that require pre-scanning such as photographic images. In addition, when the original image is a character image, the gamma correction during the main scan is performed by performing the preliminary image reading for reading the partial image of the original without performing the pre-scan for reading the entire original image. The image processing can be performed and the processing time can be shortened.
Therefore, efficient image processing according to the image of the document can be performed.
[0107]
  Claim 2According to the described invention,Claim 1Of course, it is possible to obtain the same effect as that of the invention described in 1. In particular, when a character image is selected by the image selection means, a luminance histogram of an image in a part of the document read by the preliminary image reading is obtained. The creation means creates, and based on the created brightness histogram, the gamma correction data setting means selects or calculates and sets gamma correction data for performing optimal gamma correction. Based on the data, it is possible to perform image processing for performing gamma correction during the main scan for reading the entire image of the document.
  Further, when a photographic image is selected by the image selection means, a pre-scan for extracting feature points of the entire image of the document can be performed, and gamma correction based on the result of the pre-scan can be performed during the main scan.
  That is, it is possible to select a photographic image in advance for an image that needs to be pre-scanned, such as a photographic image, and perform precise image processing for pre-scanning. Further, when the image of the document is a character image, by selecting a character image in advance and performing a preliminary image reading that reads an image of a part of the document without performing a pre-scan that reads the entire image of the document, Image processing for performing gamma correction during the main scan can be performed.
  Therefore, more efficient image processing can be performed by selecting an image of a document.
[0108]
  Claim 3According to the described invention,Claim 1 or claim 2Of course, it is possible to obtain the same effect as that of the invention described in (1). In particular, the control unit moves the image reading unit from the predetermined standby position based on the detection that the platen cover is closed by the detection unit. Since the preliminary image reading that reads a part of the image at the edge of the document is executed while moving to the position, after the preliminary image reading, the image reading unit can move from the home position to the pre-scan and main scan operations immediately. There is no waste when shifting from the preliminary image reading operation to the pre-scan or main-scan operation, and the processing operation can be made more efficient.
  Further, since the preliminary image reading is performed based on the detection that the original is placed on the platen and the platen cover is closed by the detection means, there is no need for an operation instruction for the preliminary image reading operation, and the processing operation is not performed. Efficiency can be improved.
[0109]
  Claim 4According to the described invention,Claim 3Of course, it is possible to obtain the same effect as that of the invention described in (1), in particular, after detecting that the platen cover has been closed by the detection means, the gamma correction data set by the gamma correction data setting means is at least Since it can be stored in the gamma correction data storage means until the detection means detects that the document has been opened again, it is not necessary to select gamma correction data for each document processing, and the processing operation can be made more efficient.
[0110]
  Claim 5According to the described invention,Claims 1-4Of course, it is possible to obtain the same effect as the invention described in any one of the above, and in particular, the luminance of the reference color of the shading reference plate read by the shading reference reading means by the correction value calculation means in the image processing apparatus. A luminance correction value is calculated from the second shading data based on the first shading data and the first shading data stored in the shading data storage means. Then, the luminance histogram correction unit corrects the luminance histogram created by the luminance histogram creation unit based on the luminance correction value, and the gamma correction data setting unit selects gamma correction data based on the corrected luminance histogram, Alternatively, gamma correction data is calculated using a predetermined arithmetic expression, and optimal gamma correction data is set.
  In other words, the image processing apparatus uses, for example, a luminance histogram created by correcting with the first shading data based on the luminance correction value calculated by the correction value calculation means based on the second shading data and the first shading data. The luminance histogram correction means corrects the luminance histogram based on the second shading data, so that the luminance histogram optimum for the image corrected with the second shading data can be obtained. Then, the gamma correction data setting means of the image processing apparatus selects gamma correction data based on the luminance histogram corrected to correspond to the second shading data after canceling the influence of the first shading data, or The gamma correction data can be calculated from a predetermined arithmetic expression, and optimal gamma correction data can be set.
  Therefore, the image processing apparatus can perform image formation and image processing in accordance with a predetermined standard without being affected by the first shading data.
[0111]
  Claim 6According to the described invention,Claims 1-4Of course, it is possible to obtain the same effect as the invention described in any one of the above, and in particular, the luminance of the reference color of the shading reference plate read by the shading reference reading means by the correction value calculation means in the image processing apparatus. A luminance correction value is calculated from the second shading data based on the first shading data and the first shading data stored in the shading data storage means. Then, the gamma correction data correction means corrects the gamma correction data set by the gamma correction data setting means based on the brightness correction value, and the gamma correction control means performs gamma correction based on the corrected gamma correction data. carry out.
  In other words, the image processing apparatus, for example, the gamma correction data set by correcting with the first shading data based on the luminance correction value calculated by the correction value calculation means based on the second shading data and the first shading data. Is corrected as gamma correction data based on the second shading data by the gamma correction data correction means, so that the gamma correction data optimum for the image corrected by the second shading data can be obtained. Then, the gamma correction control means of the image processing apparatus can perform gamma correction based on the gamma correction data corrected so as to correspond to the second shading data after the influence of the first shading data is cancelled. it can.
  Therefore, the image processing apparatus can perform image formation and image processing in accordance with a predetermined standard without being affected by the first shading data.
[Brief description of the drawings]
FIG. 1 is a perspective view of an image forming apparatus according to the present invention.
FIG. 2 is a cross-sectional view schematically showing an image reading unit and a document feeder provided on a platen cover in the image forming apparatus according to the present invention.
FIG. 3 is a block diagram showing a main configuration of the image forming apparatus according to the first embodiment of the present invention.
FIG. 4 is a flowchart showing an operation in the first embodiment of the present invention.
FIG. 5 is a schematic diagram of a luminance histogram. (A) is a luminance histogram of a normal character document, and (b) is a luminance histogram of a photographic document.
FIG. 6 is a flowchart showing a document type determination operation of a luminance histogram according to the present invention.
FIG. 7 is a diagram showing a luminance histogram of a background-type image (normal character original) and gamma correction data GD corresponding to the luminance histogram.
FIG. 8 is a diagram showing a luminance histogram of an inverted image (black / dark color background character original document) and gamma correction data GD corresponding to the luminance histogram;
FIG. 9 is a diagram showing a luminance histogram of another type of image (photo original) and gamma correction data GD corresponding to the luminance histogram.
FIG. 10 is a block diagram illustrating a main configuration of an image forming apparatus according to a second embodiment of the present invention.
FIG. 11 is a flowchart showing an operation according to the second embodiment of the present invention.
FIG. 12 is a block diagram illustrating a main configuration of an image forming apparatus according to a third embodiment of the present invention.
FIG. 13 is a flowchart showing an operation according to the third embodiment of the present invention.
FIG. 14 is an explanatory diagram showing a scanner head moving operation related to the operations in the third and fourth embodiments.
FIG. 15 is a block diagram illustrating a main configuration of an image forming apparatus according to a fourth embodiment of the present invention.
FIG. 16 is a flowchart showing an operation according to the fourth embodiment of the present invention.
FIG. 17 is an explanatory diagram showing a scanner head moving operation in a conventional image processing apparatus.
[Explanation of symbols]
1 Platen
2 Platen cover
3 Scanner head
4 CCD unit
5 Mirror
6 Scale board
7 Document feeder
8 White reference plate (shading reference plate)
10 Control unit
11 Preliminary image reading means
12 Luminance histogram creation means
13 Gamma correction data setting means
14 Gamma correction control means
15 Image judging means
16 Shading reference reading means
17 Correction value calculation means
18 Luminance histogram correction means
19 Gamma correction data correction means
10a CPU
10b ROM
60 recording means
10c RAM
70a Gamma correction data storage means
70b Shading data storage means
20 Image reader
30 storage unit
40 Operation unit
41 Image selection means
50 Detection part (detection means)
100, 200, 300, 400 Image processing apparatus
hg, HG brightness histogram, overall brightness histogram
GD Gamma correction data
WP standby position
HP home position

Claims (6)

An image reading unit that reads an image of a document placed on a platen, and a control unit that controls the image reading unit, and the control unit performs a reading operation for extracting image feature points of the entire image of the document An image processing apparatus that controls a pre-scan, a main scan that is an entire image reading operation for performing gamma correction based on a result of the pre-scan, and a preliminary image reading that reads an image of a part of the document. And
The controller is
A luminance histogram creating means for creating a luminance histogram of the image based on an image of a part of the document read by the preliminary image reading;
Image judging means for judging whether the image of the document is a character image or a photographic image based on a brightness histogram of a part of the image of the document created by the brightness histogram creating means;
When the image determination unit determines that the image of the document is a character image, based on the brightness histogram created by the brightness histogram creation unit, selection of optimal gamma correction data or a predetermined calculation formula Gamma correction data setting means for calculating gamma correction data;
Gamma correction control means for performing gamma correction based on the gamma correction data set by the gamma correction data setting means at the time of the main scan,
An image processing apparatus, wherein when the image determination unit determines that the image of the document is a photographic image, prescanning and main scanning of the entire image of the document are performed. The image processing apparatus according to claim 1 .
The controller is
Image selection means for selecting whether the image of the document is a character image or a photographic image;
When a character image is selected by the image selection means,
Controlling the preliminary image reading, the luminance histogram creation means, the gamma correction data setting means, and the gamma correction control means to operate,
An image processing apparatus, wherein when a photographic image is selected by the image selection means, a pre-scan and a main scan of the entire image of the document are performed. The image processing apparatus according to claim 1 or 2 ,
A detecting means for detecting the open / closed state of the platen cover;
The control unit is configured to detect the image reading unit from a standby position at a predetermined distance from a home position where the pre-scan and the main scan are started based on detection by the detection unit that the platen cover is closed. An image processing apparatus that performs the preliminary image reading for reading an image of a part of an end portion of the document while moving the image to the home position. The image processing apparatus according to claim 3 .
The controller is
After the detection means detects that the platen cover is closed, at least the detection means detects that the platen cover has been opened again based on the gamma correction data set by the gamma correction data setting means. Gamma correction data storage means for storing up to
An image processing apparatus for performing a main scan based on gamma correction data stored in the gamma correction data storage means. In the image processing device according to any one of claims 1 to 4 ,
A shading reference plate having a reference color;
A shading reference reading means for reading shading data based on the luminance of the reference color of the shading reference plate by the image reading unit;
Shading data storage means for storing the shading data read by the shading reference reading means as first shading data;
Correction value calculation means for calculating a luminance correction value from the second shading data read by the shading reference reading means and the first shading data stored in the shading data storage means;
Brightness histogram correction means for correcting the brightness histogram created by the brightness histogram creation means based on the brightness correction value calculated by the correction value calculation means,
The gamma correction data setting means selects optimal gamma correction data or calculates gamma correction data by a predetermined arithmetic expression based on the luminance histogram corrected by the luminance histogram correction means. Processing equipment. In the image processing device according to any one of claims 1 to 4 ,
A shading reference plate having a reference color;
A shading reference reading means for reading shading data based on the luminance of the reference color of the shading reference plate by the image reading unit;
Shading data storage means for storing the shading data read by the shading reference reading means as first shading data;
Correction value calculation means for calculating a luminance correction value from the second shading data read by the shading reference reading means and the first shading data stored in the shading data storage means;
Gamma correction data correction means for correcting gamma correction data set by the gamma correction data setting means based on the luminance correction value calculated by the correction value calculation means,
The gamma correction control means performs gamma correction based on the gamma correction data corrected by the gamma correction data correction means.

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