JP4043725B2 - Color image reading apparatus and color image data processing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is a color image reading apparatus such as an image scanner, a facsimile machine, a digital copying machine, etc., which reads a color image for each of a plurality of primary colors and performs processing such as color correction. The present invention relates to a color image reading apparatus and a color image data processing method for outputting image data for each of the plurality of primary colors to an apparatus (color printer, print engine, etc.).
[0002]
[Prior art]
Conventionally, in image processing in this type of color image reading apparatus, a single reading sensor is used to read a document in three primary colors / red, green, and blue (referred to as R, G, and B as appropriate) in units of one page. There is a frame sequential method. A line-sequential method is also known in which one line sensor is used to read the three primary colors R, G, and B for each color and for each line in the main scanning direction (X direction). Furthermore, using a reading sensor (three-line color sensor) equipped with three lines of photoelectric conversion cells (photoelectric conversion elements), the three-line color reading that simultaneously reads the three primary colors R, G, and B in each line in each line. The method is also known.
[0003]
Here, for example, in the three-line color reading method using the three-line color sensor, a photoelectric conversion element (corresponding to a pixel) that receives an optical image (for example, reflected light from a document) and converts it into a charge has a predetermined interval. And a plurality of color filters that allow R, G, and B color components to pass therethrough are arranged on each photoelectric conversion element. That is, one line of photoelectric conversion pixel column data is generated by repeatedly arranging photoelectric conversion elements corresponding to the respective colors of R, G, and B in the main scanning direction.
[0004]
With such a configuration, the occurrence of color misregistration or the like during color image reading in the sub-scanning direction (Y direction) is suppressed, and deterioration in image quality is prevented.
FIG. 13 is a block diagram showing a configuration of a color image reading apparatus according to a conventional three-line color reading method, and FIG. 14 is a diagram for explaining a color correction matrix in FIG. FIG. 15 is a diagram for explaining linear matrix calculation for performing color correction from R, G, and B image data to R ′, G ′, and B ′ image data. .
The color image reading apparatus shown in FIG. 13 is a main part of image processing such as an image scanner, a facsimile machine, and a digital copying machine.
[0005]
The color image reading apparatus includes, for example, a color image analog A, a color image analog-to-digital conversion processing system B, and a distortion color correction output processing system C. The color image reading system A is an object to be read (for example, a color document). The analog R, G, and B signals obtained by separating the reflected light from the photograph) into three color components by a color filter are output (this configuration is, for example, a photoelectric conversion unit or a signal selection unit. See FIG. 1 below). . In addition, the color image correction processing system B corrects the signal gain and converts analog to digital (this configuration is, for example, a gain correction unit and an A / D converter 1, see FIG. 1).
[0006]
Referring to FIG. 13, in the color correction output processing system C, digital R, G, B signals from the correction processing system described above are input, and distortion correction (shading correction) is performed here. The digital R, G, B signals are stored in the data address memory 2 as table data. The data address memory 2 is controlled by an address control unit 3. In this control, the reading order of each R, G, B signal is controlled and output to the matrix calculation unit 4. This reading order is determined by the color image output device 6 (for example, application software installed in a small general-purpose computer that processes color images, a printer of a facsimile machine or a digital copying machine) that is an output target of each R, G, B signal. It will be changed appropriately according to the specifications and applications of the engine.
[0007]
The matrix calculation unit 4 performs color correction by multiplying each R, G, B signal from the data address memory 2 by the color correction matrix shown in FIG. 14 for color flattening.
Here, the color correction will be briefly described. Color error due to chromatic aberration in optical system (color convergence error due to difference in refractive index caused by wavelength difference) or unevenness of color filter on photoelectric conversion element of 3-line color sensor (ie color density of original image and acquired color) It is the color correction process that corrects the error between the data) to be flat (which should be the original value). Such color correction processing is extremely important in a color reading apparatus (color scanner) regardless of the surface sequential, line sequential, and three-line color reading methods.
[0008]
By the way, in the color correction output processing system C, the color correction from the image data of the three colors R, G, B to the image data of the three colors R ′, G ′, B ′ is performed simply by the equation shown in FIG. This is done by linear matrix calculation. Here, the 3 × 3 square matrix is referred to as a color correction matrix, and its elements are determined theoretically and empirically.
[0009]
In the linear matrix operation in the matrix operation unit 4, operations such as k11 · R, k12 · R, k13 · R,... Are executed using the lookup table 4a, so that, for example, a multiplier is not required. It is processed at high speed. Of course, a multiplier may be used.
[0010]
The image data color-corrected by the matrix calculation unit 4 in this manner is input to the image processing unit 5 where processing such as density contrast correction and binarization processing is performed. The color image data is transferred to a color image output device 6 such as a small general-purpose computer that processes a color image, a printer engine of a facsimile machine or a digital copying machine, or a single color printer.
[0011]
In the processing by the small general-purpose computer, the captured color image is output to the connected printer as it is, another color image is added, or the input color image is partially deleted.
[0012]
[Problems to be solved by the invention]
In an image reading apparatus that processes and outputs image data for each of a plurality of primary colors as in the conventional three-line color reading system described above, when an R, G, B signal is extracted from the data address memory 2, an address is used. The extraction order is changed under the control of the control unit 3. The change process can be performed before the address control unit 3 or can be changed after the address control unit 3. In any case, in the prior art, R, G, B Required a dedicated control circuit for changing the order of signals.
[0013]
Further, when processing and outputting such image data for each of the primary colors, in addition to the address control unit 3 for changing the reading order from the data address memory 2, the read data is stacked and taken out (push-down). A register (not shown in FIG. 13) for stacking is required. In other words, in the prior art, the processing of image data for each of a plurality of primary colors and the output control thereof are complicated and complicated.
[0014]
The present invention solves such a problem in the prior art, and eliminates the need for a special control circuit, a push-down stack register, an address controller, and the like, and outputs three lines of R, G, and B signals. It is an object of the present invention to provide a color image reading apparatus and a color reading processing method that can process and output image data in color and can suppress an increase in signal processing scale and apparatus scale.
[0015]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a color image reading apparatus for correcting and outputting color image data read for each of a plurality of primary colors, and a plurality of primary color lines spaced apart in the sub-scanning direction. A reading sensor for reading a document composed of a photoelectric sensor, an inter-line correction unit for correcting inter-line correction of image data read by the reading sensor, and matrix calculation means for correcting the image data Storage means storing a product matrix of a color correction matrix for color correcting the image data and an output order defining matrix for defining the output order of the image data, and the matrix computing means includes the line It is an object of the present invention to provide a color image reading apparatus characterized by performing a matrix operation between the image data corrected between lines by the interval correction unit and the product matrix .
[0016]
Here, the reading sensor is composed of three linear photoelectric conversion sensors of R, G, and B, and integration for obtaining a product matrix of the color correction matrix and the output order defining matrix is performed by the CPU. Is called. The output order defining matrix is a 3 × 3 square matrix, and each row and column element is composed of one “1” and two “0”. The output order defining matrix is a diagonal matrix .
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The color image reading apparatus and color image data processing method according to the present invention is an apparatus for reading a color image on a document for each of a plurality of primary colors, such as a line sequential reading method and a three-line color reading method, and processing and outputting the same. And applicable to methods.
Hereinafter, an example of an embodiment of a color image reading apparatus and a color image data processing method according to the present invention will be described in detail with reference to the drawings based on a three-line color image data processing method.
FIG. 1 is a block diagram showing the configuration of an embodiment of a color image reading apparatus and color image data processing method according to the present invention. In FIG. 1, this color image reading apparatus has a light source lamp 11 that irradiates light on an image surface of a document 12.
[0018]
In this color image reading apparatus, reflected light read from the document 12 is incident through an optical system, and a photoelectric conversion is performed to output the CCD. The charge of the photoelectric conversion unit 13 and the photoelectric conversion cell (photoelectric conversion element / photoelectric conversion sensor) of the photoelectric conversion unit 13 are sequentially selected from each line, and at the timing for each pixel of the R, G, B signals. It has a signal selection unit 14 to output, and a gain correction unit 15 that corrects the level difference between the R, G, and B signals from the signal selection unit 14 and equalizes and outputs it.
[0019]
In addition, the color image reading apparatus includes an A / D converter 18 that converts analog signals (R, G, and B signals) from the gain correction unit 15 into digital signals, a non-uniformity in the amount of radiated light from the light source lamp 11, and a lens. The distortion correction unit 16 that corrects the distortion of the output signal of the photoelectric conversion unit 13 generated in the system and the correction of the dark output of the photoelectric conversion cell with the input correction data and outputs the correction data to the distortion correction unit 16 And a distortion correction memory 17 to be sent out.
[0020]
Further, the color image reading apparatus includes an inter-line correction unit 20 that performs inter-line distance correction of three lines R, G, and B, a data address memory 19 that stores R, G, and B image data, and three rows. It has a matrix calculation unit 21 (corresponding to matrix calculation means in the claims) that executes matrix calculation of three columns. The data address memory 19 is provided with a look-up table (RAM / ROM) 21a (corresponding to the matrix calculation means in the claims) for executing a matrix calculation. The color image reading apparatus includes an image processing unit 22 that performs processing such as density contrast correction and binarization processing.
[0021]
In the configuration shown in FIG. 1, a color image output device 23 that outputs color printing paper such as a small general-purpose computer that processes a color image from the image processing unit 22 or a printer engine of a single color printer, facsimile machine, or digital copying machine. have. In the processing on a small general-purpose computer, as described above, the captured color image is directly output to the connected printer, or another color image is added, or the input color image is partially deleted. Do.
[0022]
Next, the operation of this embodiment will be described.
FIG. 2 is a diagram for explaining the storage contents of the matrix and calculation in the lookup table 21a.
[0023]
In FIG. 1, radiated light from a light source lamp 11 is reflected by a color screen of a document 12, and this reflected light is provided through an objective lens array or the like, and a photoelectric conversion unit having three-line photoelectric conversion cells for R, G, and B. 13 receives light. The photoelectric conversion unit 13 photoelectrically converts incident light and outputs it, and reads the document 11. This analog photoelectric conversion signal, that is, an analog signal of one pixel unit from the photoelectric conversion cell is simultaneously output to the signal selection unit 14.
[0024]
The photoelectric conversion unit 13 is provided with a color filter or the like for color-separating input reflected light, and the reflected light passing through the color filter is incident on each photoelectric conversion cell. Here, the data output from each pixel of each of the R, G, and B lines is digitized by the A / D converter 18 after the input signal level and the like are corrected by the gain correction unit 15. The digitized signal passes through a distortion correction unit 16 (shading correction) that corrects distortion of the optical system and the color sensor.
[0025]
The distortion correction unit 16 uses the correction data from the distortion correction memory 17 to correct distortion of the output signal from the photoelectric conversion unit 13 generated by the amount of radiation of the light source lamp 11 and dark output of the photoelectric conversion cell. Are output to the data address memory 19 and stored therein.
[0026]
A matrix operation unit 21 performs a 3 × 3 matrix operation on the R, G, B image data stored in the data address memory 19. In this matrix, elements of the result matrix of the product of the color correction matrix described with reference to the conventional example and the matrix that defines the output of image data in three line colors are stored. For example, in the matrix calculation in the look-up table 21a shown in FIGS. 2A and 2B, the matrix element is a matrix element obtained by multiplying the color correction matrix A by the next unit matrix V in advance. The matrix operation is executed based on the element data. As a result, the output order of 3-line color image data corresponding to the order of G, B, and R is defined.
[0027]
More specifically, the look-up table 21a used for performing the matrix operation is composed of rewritable storage means (for example, RAM), and element data from a personal computer connected to the color image reading apparatus. Will be downloaded. The color correction matrix A and the matrix V for determining the order in which the 3-line color output image data is constructed are instructed by this personal computer, and the color image reading apparatus is stored together with the firmware. The matrix A and matrix V parameters are calculated in the firmware CPU, and the parameters for the lookup table 21a are calculated and set. In the embodiment, a configuration that uses either configuration according to the external device to be connected is used.
[0028]
FIG. 3 is a diagram for explaining the calculation contents of the matrix for defining the output of the image data in three line colors and the sequential change of R, G, B. FIG. 4 defines the output of the image data in the three line colors. It is a figure for demonstrating the calculation content of the sequential change of a matrix and R, G, B. FIG. 5 is a diagram for explaining the calculation contents of the matrix for defining the output by the color image data by the three-line color and the sequential change of R, G, and B, and FIG. 6 is the image data by the three-line color. FIG. 6 is a diagram for explaining the calculation contents of the matrix that defines the output of and the sequential change of R, G, and B; Further, FIG. 7 is a diagram for explaining the calculation contents of the matrix for defining the output of the image data in three line colors and the sequential change of R, G, B, and FIG. This is for explaining the matrix for defining the output and the calculation contents of the sequential change of R, G, and B.
[0029]
A matrix of 3 rows and 3 columns that defines a change in the output order of image data in 3 line colors is a matrix in which each row and column element is composed of one “1” and two “0 (zero)”. 6 to 6 matrixes shown in FIGS. This coincides with the permutation combination of R, G, B.
[0030]
Such a synthesized matrix is stored in the lookup table 21 a of the matrix calculation unit 21. The matrix calculation unit 21 performs calculation processing for color correction. At the same time, the signal output order after R, G, B color correction is changed.
[0031]
Image data that has undergone color correction by the matrix calculation unit 21 and whose signal output order has been changed is input to the image processing unit 22. Processing such as density contrast correction and binarization processing is performed by the image processing unit 22, and the color image data is transferred to the color image output device 23.
[0032]
In this way, the signal output order after the R, G, B color correction is performed so that the image data of the three colors R, G, B by the three-line color reading method is adapted to the image generation characteristics of the color image output device 23. Is changed. As a result, print output by various color image output devices 23 becomes possible.
[0033]
A specific example of the color image reading apparatus shown in FIG. 1 is a local area network (LAN) configuration that can be connected to a plurality of types of printers, as will be described with reference to FIGS. This scanner outputs color signals in an appropriate order. The scanner or personal computer identifies the type and specification of the printer and changes the element order of the color correction matrix, or the scanner or personal computer having the color output order for each type of printer.
[0034]
Next, a specific configuration example for changing the signal output order corresponding to the image generation characteristics in the color image processing apparatus or the color image output apparatus will be described.
FIG. 9 is a block diagram showing a specific main part configuration of this embodiment, and FIG. 10 is a block diagram showing another specific main part configuration of the embodiment. FIG. 11 is a block diagram showing still another specific principal part configuration of the embodiment, and FIG. 12 is a block diagram showing still another concrete principal part configuration of the embodiment.
[0035]
Referring to FIG. 9, in this configuration example, a lookup table (RAM / ROM, corresponding to the information recording medium in claims) 21a is mechanically mounted and exchanged in a matrix operation unit 21 by a plug-in method. It is a configuration. Connection / reading means for this purpose is provided in the matrix calculation unit 21. The connection / reading unit includes, for example, a connection connector and an interface (I / F) unit. In the look-up table (RAM / ROM) 21a, the matrix for defining the output of image data in any one of the three-line colors shown in FIGS. 3 to 8 and the calculation data (hereinafter referred to as R, G, B) are changed. And matrix / sequential change data) are stored and mounted in the matrix calculation unit 21, thereby setting the matrix / sequential change data suitable for the image generation characteristics of the color image output device 23 in the matrix calculation unit 21. .
[0036]
Referring to FIG. 10, in this configuration example, all the matrix / sequentially changed data of FIG. 3 to FIG. 8 are stored in the lookup table (RAM / ROM) 21a of the matrix operation unit 21, and this lookup table is stored. (RAM / ROM) 21 a is mounted on the matrix calculation unit 21. Then, the matrix / sequential change data suitable for the image generation characteristics of the color image output device 23 is converted from all the matrix / sequential change data of FIGS. 3 to 8 to the I / F unit 28 and the DIP switch 29 (in the claims). Select (operate corresponding to mechanical switching means). That is, it is mechanically selected and set in the matrix calculation unit 21.
[0037]
Referring to FIG. 11, in this configuration example, all the matrix / sequentially changed data of FIGS. 3 to 8 described above are stored in the lookup table (RAM / ROM) 21a of the matrix calculation unit 21, and the matrix calculation unit 21. 3 to FIG. 8, the system MPU (microprocessor) 30 for controlling the entire color image reading apparatus, and the input operation device (for example, keyboard or coordinate input device). Selection is made by the control operation by 30a. By this selection, matrix / sequential change data that matches the image generation characteristics of the color image output device 23 is set in the matrix calculation unit 21.
[0038]
The system MPU 30 and the input operation device 30a shown in FIG. 11 correspond to the control means in the claims. When the color image reading apparatus shown in FIG. 11 is accommodated in a local area network (LAN) such as Ethernet, the image reading apparatus functions as a so-called network scanner, and the system MPU 30 receives a switching control signal from the host computer. By taking in, the same operation as described in FIG. 11 can be performed.
[0039]
Further, when the color image reading apparatus shown in FIG. 11 is accommodated in a client / server system, the same operation is performed even when the system MPU 30 captures a switching control signal by a remote procedure call (RPC) from the server. I can do it.
[0040]
Referring to FIG. 12, in this configuration example, all the matrix / sequentially changed data in FIGS. 3 to 8 are stored in the look-up table (RAM / ROM) 21a of the matrix calculating unit 21, and the matrix calculating unit 21. Then, from all the matrix / sequentially changed data of FIGS. 3 to 8, data indicating image generation characteristics from the color image output device 23, for example, a status signal is sent to the I / F unit 35 (capture setting in claims). A setting signal corresponding to the status signal is generated. Based on this setting signal, matrix / sequential change data matching the image generation characteristics of the color image output device 23 is automatically selected and set in the matrix calculation unit 21.
[0041]
Note that the data indicating the image generation characteristics, for example, the status signal is taken in by the system MPU 30 shown in FIG. 11 and the matrix / sequential change data is automatically selected and set in the matrix calculation unit 21. good.
[0042]
Note that when the color image reading apparatus shown in FIG. 12 is accommodated in a local area network (LAN) such as Ethernet, the I / F unit 35 captures the switching control signal from the host computer as described above. The same operation as described in FIG. 12 can be performed.
[0043]
Further, when the color image reading apparatus shown in FIG. 12 is accommodated in a client / server system, the same operation is performed when the I / F unit 35 captures a switching control signal by remote procedure call (RPC) from the server. Can be done. In this embodiment, the matrix of 3 rows and 3 columns shown in FIG. 3 is exemplified as the matrix that defines the output of the image data in three lines, but the present invention is not limited to this. For example, an embodiment relating to output processing of image data in three line colors using a matrix corresponding to the number of signal outputs of color components such as C, M, Y, and B is also included in the present invention.
[0044]
According to the present invention, in order to correct color image data read for each of a plurality of primary colors and output the image data subjected to the color correction processing, the color correction matrix and the output order of the color image data for each of the plurality of primary colors Using a product matrix selected from one or a plurality of product matrices of the matrix to change the color image data so that the processing data of the color image data is adapted to the characteristics of the image generating device, or one rewritable memory By changing parameters and using them, color correction and change processing of the output order of color image data for a plurality of color data that have been taken in are executed.
[0045]
Therefore, for example, it becomes possible to process the color image data read for each of the primary colors and output it to an external device without the need for a control circuit or a push-down stack register, thereby complicating the signal processing. And it becomes possible to suppress complication.
[0046]
Further, from the product data of a plurality of matrices that define the color correction matrix and the output of the color image data read for each of the plurality of primary colors, product matrix data corresponding to the characteristics for generating the output data is mechanically selected, or Automatic electrical selection.
[0047]
Accordingly, output control of various color image data becomes possible, and various color image reading apparatuses can be configured. Furthermore, it becomes possible to cope with a color image processing apparatus or a color image output apparatus having various image generation characteristics.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of an embodiment of a color image reading apparatus according to the present invention and a method of processing color image data read for each of a plurality of primary colors.
FIG. 2 is a diagram for explaining a determinant for processing image data with three line colors and the content of calculation in the present embodiment.
FIG. 3 is a diagram for explaining the contents of a second determinant and calculation in the present embodiment.
FIG. 4 is a diagram for explaining a third determinant and the content of calculation in the present embodiment.
FIG. 5 is a diagram for explaining a fourth determinant and the content of calculation in the present embodiment.
FIG. 6 is a diagram for explaining a fifth determinant and the content of calculation in the present embodiment.
FIG. 7 is a diagram for explaining a sixth determinant and contents of calculation in the present embodiment;
FIG. 8 is a diagram for explaining a seventh determinant and the content of calculation in the present embodiment;
FIG. 9 is a block diagram showing a specific main configuration of the present embodiment.
FIG. 10 is a block diagram showing another specific essential configuration of the present embodiment.
FIG. 11 is a block diagram showing still another specific essential configuration of the present embodiment.
FIG. 12 is a block diagram showing still another specific essential configuration of the present embodiment.
FIG. 13 is a block diagram illustrating a main configuration of a conventional color image reading apparatus.
FIG. 14 is a diagram for explaining a color correction determinant in the prior art.
FIG. 15 is a diagram for explaining linear matrix calculation for performing color correction in the prior art.
[Explanation of symbols]
11 Light source lamp 12 Document 13 Photoelectric conversion unit 14 Signal selection unit 15 Gain correction unit 16 Distortion correction unit 17 Distortion correction memory 18 A / D converter 19 Data address memory 21 Matrix operation unit 21a Look-up table 22 Image processing unit 23 Color Image output device 29 DIP switch 30 System MPU
30a Input operation device

Claims (5)

A color image reading apparatus for outputting correction color image data read for each of a plurality of primary colors,
A reading sensor for reading a document composed of a plurality of primary color line-shaped photoelectric conversion sensors separated in the sub-scanning direction;
An interline correction unit for performing interline correction of image data read by the reading sensor;
Matrix calculation means for correcting the image data;
Storage means for storing a product matrix of a color correction matrix for color correcting the image data and an output order defining matrix for defining an output order of the image data;
With
The color image reading apparatus , wherein the matrix calculation means performs a matrix calculation of the image data corrected by the line correction unit and the product matrix . 2. The color image reading apparatus according to claim 1, wherein the reading sensor is constituted by three linear photoelectric conversion sensors of R, G, and B. The color image reading apparatus according to claim 1, wherein the integration for obtaining a product matrix of the color correction matrix and the output order defining matrix is performed by a CPU. The output sequence defined matrix is a square matrix der of three rows and three columns is, the elements of each row and column, claims 1 to 3, one of "1", characterized in that it consists of two "0" A color image reading apparatus according to any one of the above. The output sequence defined matrix, color image reading according to any one of claims 1 to 3, characterized in that a diagonal matrix device.

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