JPH07274026A - Picture processor and its method - Google Patents

Abstract

PURPOSE:To provide a picture processor and a its method capable of performing color space compression and obtaining improved pictures for which hardware constitution is reduced and a cost is reduced. CONSTITUTION:The picture signals of original pictures read by an image sensor 34 are sampled in a sampling part 123 and stored in the memory of a variable magnification part 122. A CPU part 116 calculates a matrix transformation coefficient by a base level, color distribution and a dark level detected from the picture signals stored in the memory and sets it to a color space comparession part 121. The picture signals outputted from the image sensor 34 again are matrix-transformed in the color space compression part 121, sent to a printer part and printed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus and a method thereof, and more particularly to an image processing apparatus and a method thereof for performing image processing such as color space compression on a color image signal.

[0002]

2. Description of the Related Art In a device for outputting a hard copy of an input color image, the color reproducibility of the hard copy output image,
It is desirable that the gradation and the like be reproduced faithfully with respect to the original image. However, in reality, it is difficult to faithfully reproduce due to the difference between the color distribution of the original image and the color reproduction range of the hard copy output device. Therefore, in order to absorb the difference in the color reproduction range and reproduce the original image as faithfully as possible, an image processing apparatus that performs color space compression using a look-up table on the input color image and outputs it has been considered. There is.

On the other hand, there is known an image processing system for inputting a color image from a plurality of input units such as an image scanner and an external device.

[0004]

However, the above-mentioned conventional example has the following problems. Since color space compression is performed using a look-up table, the circuit configuration becomes complicated, and a large memory size is required, which causes a problem of increased cost. When the input units are different, an image signal that is not color space compressed may be input from one input unit and an image signal that is color space compressed may be input from the other input unit. obtain. Therefore,
There is a problem that the image signal already subjected to the color space compression is subjected to the color space compression again, and the output image is remarkably deteriorated.

The present invention is to solve the above-mentioned problems, and its purpose is as follows. It is an object of a first invention of the present application to provide an image processing apparatus and a method thereof that can obtain a good image by performing color space compression with a reduced hardware configuration and cost reduction. A second invention of the present application is an image processing apparatus and method capable of obtaining an excellent image by preventing unnecessary deterioration of image quality by not performing color space compression on an image signal that does not require color space compression. The purpose is to provide.

[0006]

The present invention has the following structure as one means for achieving the above object. An image processing method according to the present invention comprises a determination step of determining a color distribution and a background level of the document image based on the image signal obtained by the first scanning of the input unit which scans the document image and inputs the image signal. , And a color conversion step of performing color space compression and adjustment of the background level on the image signal obtained by the second scanning by the input means based on the determination result of the determination step.

Further, a calculation step for calculating a plurality of coefficients based on the image signal obtained by the first scanning of the input means for scanning the original image and inputting the image signal; And a color space compression step of performing color space compression on the image signal obtained by the second scanning by the input means by matrix conversion based on the coefficient of.

Further, a color space compression step of performing color space compression on the image signal input by the first input means for inputting an image signal for scanning the original image, and an image output from the color space compression step. An image processing method comprising a conversion step of converting a signal into an output signal, wherein the image signal input by the second input means for inputting the image signal from an external device is the above-mentioned without the color space compression step. It is characterized in that it is input to the conversion step.

An image processing apparatus according to the present invention comprises an input means for scanning a document image and inputting an image signal, and a color distribution of the document image based on the image signal obtained by the first scanning by the input means. And a color conversion unit for performing color space compression and adjustment of the background level on the basis of the result of the determination by the determining unit for the image signal obtained by the second scanning by the input unit. It is characterized by

Also, input means for scanning the original image to input the image signal, calculating means for calculating a plurality of coefficients based on the image signal obtained by the first scanning by the input means, and the calculating means. Color space compression means for compressing the color space of the image signal obtained by the second scanning by the input means by matrix conversion based on the plurality of coefficients calculated by the above.

Further, first input means for scanning the original image to input the first image signal, second input means for inputting the second image signal from an external device, and the first image signal. An image processing apparatus comprising: a color space compression unit that performs color space compression on a color image, and a conversion unit that converts an image signal output from the color space compression unit into an output signal, wherein the second image signal Is input to the conversion means without passing through the color space compression means.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An image processing apparatus according to an embodiment of the present invention will be described in detail below with reference to the drawings. In the following embodiments, an example in which the present invention is applied to an electrophotographic color copying machine will be described, but the present invention is not limited to this, and an ink jet type color copying machine, an electrophotographic method or It goes without saying that the invention can be applied to an inkjet printer, an image processing unit (hereinafter referred to as “IPU”) that does not include an image forming unit, and the like.

[0013]

First Embodiment [Structure of Main Body] FIG. 1 is a schematic view of an image processing apparatus according to an embodiment of the present invention. An upper portion thereof is a reader unit for performing image processing by reading a color image, and a lower portion thereof is a reader unit. The printer unit prints an image or the like read by the printer.

In the reader section, the original 30 is placed on the original table glass 31, and the optical system reading drive motor 35
A known document scanning unit including the exposure lamp 32 is scanned at a constant speed according to a preset copy magnification. Then, the reflected light image from the original 30 is condensed on the image sensor 34 by the lens 33 to obtain a color-separated image signal. As the image sensor 34, for example, a three-line CCD, which is arranged adjacent to each other and includes red R, green G, and blue B filters, is used.

The color-separated image signal output from the image sensor 34 is used as an image processing unit 36 and a controller unit 37.
After being subjected to image processing in (1), it is sent to the printer section. An operation unit is provided around the platen glass 31, and switches for setting various modes related to the copy sequence and a display for display are arranged.

In the printer section, a photosensitive drum 1 which is an image bearing member is rotatably supported in the direction of an arrow, and a pre-exposure lamp 11, a corona charger 2, a laser exposure optical system 3 are provided around the photosensitive drum 1. Potential sensor 12, developing device 4 for each color
A light amount detector 13, a transfer device 5, and a cleaning device 6 are arranged. The image signal from the reader unit is converted into a laser light signal in the laser exposure optical system 3, and the laser light E
Is reflected by the polygon mirror 3a, passes through the lens 3b and the mirror 3c, and is irradiated onto the surface of the photosensitive drum 1.
During image formation, rotate the photosensitive drum 1 in the direction of the arrow,
After the charge is removed by the pre-exposure lamp 11 and uniformly charged by the charger 2, a latent image is formed for each color separation image.

Next, the predetermined developing device 4 is operated to develop the formed latent image to form a toner image using resin as a substrate. The developing device 4 includes eccentric cams 24y, 24m, 24c, 24.
By the operation of k, the photosensitive drum 1 is selectively approached according to each separated color. Further, the toner image formed is transferred from any one of the preselected recording paper cassettes 7a, 7b, 7c to the recording paper supplied to the position facing the photosensitive drum 1 via the transport system and the transfer device 5. . The selection of the recording paper cassette 7 is performed by driving any one of the pickup rollers 27a, 27b, 27c by a control signal from the controller unit 37 according to the size of the recorded image.

The transfer device 5 includes a transfer drum 5a,
Transfer charger 5b, adsorption charger 5c for electrostatically attracting recording paper
And a suction roller 5g, an inner charging device 5d, and an outer charging device 5e facing each other. A recording paper carrying sheet 5f made of a dielectric material is integrally stretched in a cylindrical shape in the peripheral opening area of the transfer drum 5a which is rotatably driven. A dielectric sheet such as a polycarbonate film is used as the recording paper carrying sheet 5f. As the transfer drum 5a is rotated, the toner image on the photosensitive drum 1 is transferred onto the recording paper carried on the recording paper carrying sheet 5f by the transfer charger 5b.

In this way, a desired number of color images are transferred to the recording paper that is adsorbed and conveyed by the recording paper carrying sheet 5f, and a full-color image is formed. When the transfer of the four-color toner image is completed, the recording paper is separated from the transfer drum 5a by the action of the separation claw 8a, the separation push-up roller 8b, and the separation charger 5h, and is discharged to the tray 10 via the fixing device 9. It

On the other hand, the photosensitive drum 1 is cleaned of residual toner on the surface thereof by the cleaning device 6 after the transfer is completed,
The image forming process is performed again. When images are formed on both sides of the recording paper, the guide 19 is driven so that the recording paper discharged from the fixing device 9 passes through the conveyance vertical path 20 and the reverse path 21.
After being guided to a, the reversing roller 21b is reversed so that the reversing roller 21b is led out in the direction opposite to that of the introduction and is stored in the intermediate tray 22. After that, an image is formed on the other surface through the above-described image forming process.

Further, in order to prevent powder such as toner from adhering to the recording paper carrying sheet 5f and prevent oil from adhering to the recording paper, the fur brush 14 and the recording paper carrying sheet 5f are used to remove the powder. Cleaning is performed by the backup brush 15 facing the brush 14, and the backup brush 17 facing the roller 16 via the oil removing roller 16 and the recording paper carrying sheet 5f. Such cleaning is performed before and after image formation, and at any time when a jam (paper jam) occurs.

Further, in this embodiment, the eccentric cam 25 is operated at a desired timing to operate the cam follower 5i integrated with the transfer drum 5a, whereby the recording paper carrying sheet 5f and the photosensitive drum 1 are separated from each other. The gap can be set arbitrarily. For example, during standby or when the power is off, the transfer drum 5a and the photosensitive drum 1 are separated from each other.

[Image Processing Block] FIG. 2 shows the image processing unit 3
6 is a block diagram showing a configuration example of a controller unit 37 and its periphery. FIG. In the figure, the image sensor 34
Is composed of three line CCDs for reading R, G, and B images of 101 to 103, respectively, and color-separates one line of light information reflected from the original to output an RGB image signal at a resolution of 400 dpi. To do. In this embodiment, one line has a maximum of 297 mm.
To read (A4 portrait) lines CCD101-103
Output image signals of 4,677 pixels / line respectively.

A main scanning address counter 104 is a signal VC which is cleared by a signal BD which is a laser recording synchronization signal for each line and which is input from a pixel clock generator 105.
The LK is counted and read from the image sensor 34.
The count output H-ADR corresponding to each pixel on one line is generated. Since this signal H-ADR counts up from 0 to 5,000, the image signal for one line can be sufficiently read from the image sensor 34.

Reference numeral 106 denotes a CCD drive signal generator, which is a signal H-ADR.
To generate a CCD shift pulse, a reset pulse, and a signal CCD-DRIVE that is a transfer clock. As a result, in synchronization with the signal VCLK from the image sensor 34,
R, G, B color separation image signals for the same pixel are sequentially output. 107 is an analog / digital converter A / D, which is RGB
The image signal is converted into, for example, an 8-bit digital signal.

Reference numeral 121 denotes a color space compression unit which, under the control of the CPU unit 116, applies a matrix operation of the following formula to the input RGB image signal. However, the minimum values of X: R, G, B FIG. 3 is a block diagram showing a detailed configuration example of the R signal calculation unit of the color space compression unit 121.

In the figure, 301 is a minimum value extraction circuit MI.
At N, the signal of the minimum value is extracted from the input RGB signal, and the minimum value signal X is output. 302, 303, 304 are subtractors, respectively, which are the difference between the input RGB signal and the minimum value signal X, R-
Output X, GX, BX respectively. 305 to 312 are multipliers, and the multiplier 305 is a matrix conversion coefficient.
a11 × (RX), the multiplier 306 calculates a12 × (GX), and the multiplier 3
07 is a13 × (BX), multiplier 308 is a14 × (RX) (GX),
The multiplier 309 is a15 × (GX) (BX), and the multiplier 310 is a16 × (GX) (BX).
(BX) (RX) and the multiplier 311 respectively calculate a17 × RGB. Further, the multiplier 312 inputs the signal inverted by the inverter 314, and is thus a18 × (255-R) (255-G)
Calculate (255-B).

Reference numerals 315 and 316 denote adders, and the adder 316 outputs an R ′ signal obtained by adding the calculation result Σ of the adder 315 (sum of multiplication results) and the R signal. Although not shown in detail, G ′ and B ′ signals are also generated by the same configuration.
Referring again to FIG. 2, reference numeral 108 denotes a logarithmic converter LOG, which performs a logarithmic conversion of the 8-bit RGB image signal to produce cyan C, magenta M,
Yellow Y Outputs 8-bit density signals.

Reference numeral 109 denotes a UCR / masking processing unit, which is known
A black K density signal is extracted from the CMY three-color density signals by UCR processing, and a known masking operation for removing color turbidity of the developer corresponding to each density signal is performed. The density signal corresponding to the color image formed by the selector 110 is selected from the density signals of M ′, C ′, Y ′, and K ′ thus generated. Signal CS is the CPU part 1 for this color selection.
It is a 2-bit signal output from 16 and the signal CS is' 0.
When it is 0 ', the M'signal, when the signal CS is'01', the C'signal, when signal CS is' 10 ', the Y'signal, and signal CS is'11'
, The K'signal is selected and the image data READ
-It is output as DT.

Reference numeral 123 is a sampling unit, which receives the input RG.
B image signal and the density signal ND generated from the signal,
For example, it samples every four pixels and outputs a serial signal SMP-DT in the order of R, G, B, ND. The density signal ND is calculated by (R + G + B) / 3, for example. A selector 112 selects and outputs the signal READ-DT or the signal SMP-DT under the control of the CPU unit 116.

Reference numeral 122 is a variable power unit, and at least the image signal 1
The memory for lines is provided, and the image input from the selector 112 is enlarged or reduced in the main scanning direction under the control of the CPU unit 116. Also, at the time of sampling, CPU unit 1
16, the sampling data SMP-DT is stored in the memory and used for creating a histogram. Since the sampling rate of the sampling data SMP-DT can be set according to the storage capacity of the memory of the scaling unit 122, the storage capacity of the memory may be relatively small.

Reference numeral 113 denotes a laser driver, which is a variable power unit 122.
Laser element 113a according to the signal VIDEO input from
Control the amount of light emitted. The laser light emitted from the laser element 113a is scanned in the axial direction of the photosensitive drum 1 by the polygon mirror 3a to form an electrostatic latent image on the photosensitive drum 1. 1
A photodetector 14 is provided in the vicinity of the photosensitive drum 1, detects the passage of the laser beam immediately before scanning the photosensitive drum 1, and generates a line synchronization signal BD.

Reference numerals 303 and 304 denote font sensors, which detect that the transfer drum 5a has rotated to a predetermined position and generate page synchronization signals ITOPA and ITOPB, respectively. The AND gate 305 logically ANDs the signal ITOPB and the signal ITOP-GT of the CPU section 116, and the OR gate 306 the signal ITOPA and the AND gate 30.
OR the output of 5. Output ITOP of OR gate 306
Is the sub-scanning address counter 118 and the CPU unit 116.
Is input to.

A sub-scanning address counter 118 is a signal
Initialized by ITOP, the signal BD is counted to generate a sub-scanning address count value. The CPU unit 116 is composed of, for example, a one-chip microcomputer, and controls the present embodiment by a program stored in a built-in ROM. For example, according to the number of copies and the operation mode instructed from the operation unit 51, the reading motor controller 1
Image reading is controlled via 17 and image recording is controlled via the I / O port 120. That is, the reading motor controller 117 controls forward / backward movement and speed of the reading motor 35, and the I / O port 120 relays signals from sensors other than the above necessary for controlling copying operation and signals to actuators. To do. The signal relaying the I / O port 120 is a signal PF for feeding the recording paper from the recording paper cassette 7.
Is also included. In addition, a recording paper size signal detected by a recording paper size sensor (not shown) attached to the recording paper cassette 7 is also included.

[Sequence] Next, the color space compression sequence will be described. FIG. 4 is a flow chart showing an example of the color space compression procedure. When the original 30 is placed on the original table glass 31 and the copy start key of the operation unit 51 is pressed, CP
It is executed by the U unit 116. The CPU unit 116 uses the built-in RAM and the memory of the scaling unit 122 as a work memory to execute the following calculations.

First, initial setting is performed in step S402. At this time, the selector 112 is caused to select the signal SMP-DT, and the memory of the scaling unit 122 is initialized. Next, in step S403, a prescan operation, which is a first scan for reading an original image by the optical system, is performed. At this time, the printer unit is not operated. Subsequently, in step S404, the read RGB image signal is converted in the order of R, G, B, and ND by the sampling unit 123 and sequentially written in the memory of the scaling unit 122,
A histogram of that signal level is generated. Based on this histogram, the background level, color distribution, and dark level are detected in step S405.

FIG. 5 is a diagram for explaining an example of background level detection. Two signals (for example, R signal and G signal) of R, G, and B are set as a set, and the data of the memory address corresponding to the two values is incremented. The histogram thus obtained is represented as two-dimensional contour lines as shown in an example in FIG. 5. The most frequently appearing portion is the background level of the image. In the figure, the background level is (Rw, Gw )
Is. Similarly, if Bw is obtained from, for example, a combination of the R signal and the B signal, the background level (RGB) w can be obtained.

Next, FIGS. 6 and 7 are views for explaining an example of color distribution detection. In the figure, reference numeral 401 represents a color reproduction range of a CRT, and 402 represents a color reproduction range of a printer unit. If the signal value of a pixel in the input image is Rs, Gs,
If it is Bs, and expressed in Luv space, it becomes a point S indicated by 403. Here, consider a magenta direction vector as shown in FIG. 7, which is obtained by enlarging an area indicated by 400 in FIG. Note that M _H is the coordinates of the printed output in Luv space, and M _C is C
The coordinates of RT in Luv space. Vector M _H S from M _H to the point S (input color), the vector M _H M _C direction cosine r from M _H to M _{C
When M} is obtained, it can be seen that the larger r _M is, the higher the saturation of the point S (input color) in the magenta direction is. r _M can be obtained by the following inner product calculation.

R _M = (M _H S, M _H M _C ) / | M _H M _C ｜ ... (2) where (X, Y): dot product of vectors X and Y ｜ Z ｜: absolute value of vector Z Similarly, for other primary colors, the direction cosines r _R , r _G ,
If r _B , r _C , and r _Y are found and the maximum one is selected from these, the color in which direction the input color is, that is, the hue can be obtained. In this way, for all pixels in the input image, or for pixels sampled at regular intervals, the maximum value of the direction cosine is obtained for each color, and the Luv value that gives this maximum value is inversely transformed to obtain the maximum value. Among the color signals that deviate from the color reproduction range of each part, the RGB signal values with the highest saturation of each of the basic primary colors R, G, B, C, M, Y, that is, (RGB) R, (RGB) G, (RGB ) B, (R
GB) C, (RGB) M, (RGB) Y can be obtained.

Next, the detection of the dark level will be described. For example, among R <Rpd and G <Gpd and B <Bpd ... level
Detect as (RGB) D. Note that Rpd, Gpd, and Bpd are RGB signal values of the darkest gray that can be reproduced by this embodiment, and are stored in advance in the ROM or the like.

Then, in step S406, the matrix conversion coefficients a11 to a38 of the equation (1) are obtained. That is, a total of 24 values of the detected background level, color distribution, and dark level are set as the value RGB before conversion, and the maximum value reproducible by the present embodiment stored in the ROM or the like in advance is the converted value R'G. As “B”, the matrix conversion coefficients a11 to a38 of the equation (1) are calculated by solving 24 simultaneous linear equations. That is, by this calculation, the background of the image signal input to the color space compression unit 121 is removed, the color distribution thereof is mapped within the color reproduction range of the printer unit, and dynamics are performed without impairing the gradation of the dark portion. Matrix conversion coefficient a11 to a that can compress range
You can get 38.

Subsequently, in step S407, the calculated matrix conversion coefficients a11 to a38 are set in the color space compression unit 121, and the selector 112 is caused to select the signal READ-DT. Next, in step S408, the recording paper according to the output size is fed by the signal PF, and in step S409, the reading motor controller 117 is controlled to move the optical system to read the original image in the second and subsequent scans. Perform a certain main scan operation. The read image signal is subjected to matrix calculation in the color space compression unit 121 by the matrix conversion coefficients a11 to a38 set in step S407.

Next, in step S410, the selector 11
The magenta component signal M ′ selected by 1 is recorded on the photosensitive drum 1, developed, and transferred to recording paper. Similarly, the cyan component signal C ′, the yellow component signal Y ′, and the black component signal K ′ are recorded, developed, and transferred in this order, and a full-color image is printed out. As described above, according to the present embodiment, the background level correction, the color space compression, and the dark level correction can be collectively processed by the matrix conversion, so that each correction affects other corrections. It is possible to obtain a good processing result. Furthermore, since the processing unit that performs the correction by the matrix conversion can be integrated into one processing block such as the color space compression unit, the cost can be reduced without increasing the hardware scale.

[0044]

[Second Embodiment] An image processing apparatus according to a second embodiment of the present invention will be described below. In the second embodiment, the first
About the same configuration as the embodiment, the same reference numerals are given,
Detailed description thereof will be omitted. As shown in FIG. 3, the color space compression unit 121 of the above-described embodiment multiplies all the matrix conversion coefficients of the matrix calculation of Expression (1) by the image signal. However, since the output of any one of the subtractors 302, 303, 304 in FIG.
The output of any one of 306 and 307 is always zero, and the output of any two of the multipliers 308, 309 and 310 is always zero. Therefore, the multiplication circuit can be simplified.

FIG. 8 shows the color space compression unit 121 of the second embodiment.
3 is a block diagram illustrating a detailed configuration example of an R signal calculation unit. FIG.
In the figure, a comparator 601 outputs a maximum value MAX, an intermediate value MED, and a minimum value MIN of the values of the input signals RGB. 602 and 603 are subtractors, respectively, MAX-
Calculates MIN and MED-MIN.

Reference numerals 604 to 606 denote multipliers, respectively. The multiplier 604 is a1a × (MAX-MIN), and the multiplier 605 is a1b × (ME.
The multiplier 606 calculates a1c × (MAX-MIN) (MED-MIN). Here, the coefficients a1a and a1b correspond to the terms of the maximum value MAX and the intermediate value MED of the matrix conversion coefficients a11, a12, and a13, respectively. The coefficient a1c corresponds to the multiplication term of the maximum value MAX and the intermediate value MED among the matrix conversion coefficients a14, a15, and a16.

The adder 315 calculates the sum of the multiplication results of the multipliers 604 to 606 and the multiplication results of the multipliers 311 and 312, and the adder 316 calculates the calculation result Σ of the adder 315.
An R ′ signal obtained by adding the (sum of multiplication results) and the R signal is output. Thus, as can be seen by comparing FIG. 8 and FIG. 3, in the present embodiment, the number of adders and the number of multipliers can be reduced to three and the circuit of the color space compression unit 121 can be simplified. .

As described above, according to this embodiment,
In addition to the effect similar to that of the first embodiment, the processing unit for performing the correction can be simplified to further reduce the cost.

[0049]

[Modification] An image signal input from an external device such as a computer may be subjected to color space compression or the like in the device. FIG. 9 is a block diagram showing a configuration example in which an image signal input from an external device is not subjected to color space compression, and the CPU unit 116 is provided between the color space compression unit 121 and the logarithmic conversion unit 108 of the above-described embodiment. Area signal A set by
The selector 140 controlled by REA is provided to switch between an image signal from an external device and an image signal from the color space compression unit 121.

When the image signal from the IPU which is an external device and the image signal obtained by reading the original image are so-called inset-combined, the image signal from the IPU is already subjected to color space compression. Although it is not necessary to pass through the color space compression unit 121, the image signal obtained by reading the original image is not included in the color space compression unit 1.
Pass 21. In the case of the inset composition, the composition area is specified directly from a digitizer, a host computer or the like, by address specification via the IPU, or by marker specification. These pieces of synthesis area designation information are input to the CPU unit 116 as an image data header via an interface (not shown), and C
The PU unit 116 generates a signal AREA according to the result of analyzing the header.

By doing so, it is possible to prevent the image input from the external device from being repeatedly subjected to color space compression, prevent the image from deteriorating, and obtain an appropriate print output. Even when the input image and the read image are combined, an appropriate combined print output can be obtained. Further, in the above-described embodiment, an example has been described in which the matrix conversion coefficient is calculated from the image signal obtained by the prescan and set in the color space compression unit 121, and the image signal obtained by the next scan is matrix-converted. For example, the image signal is temporarily stored in the image memory, and the stored image signal is stored in the color space compression unit 121 and the sampling unit 12.
With the configuration of inputting to 3, the scan can be completed once.

The present invention may be applied to either a system composed of a plurality of devices or an apparatus composed of a single device. Further, it goes without saying that the present invention can be applied to the case where it is achieved by supplying a program to a system or an apparatus. Further, the present invention is
It may be used for a head of a type that ejects ink by causing film boiling due to thermal energy and an image processing apparatus to which a recording method using the same is applied.

[0053]

As described above, according to the first invention of the present application, the image processing apparatus capable of obtaining a good image by performing the color space compression with the hardware configuration reduced and the cost reduced. And a method therefor can be provided. Further, according to the second invention of the present application, an image processing apparatus capable of preventing an unnecessary deterioration of image quality and obtaining a good image by not performing color space compression on an image signal which does not require color space compression, The method can be provided.

[Brief description of drawings]

FIG. 1 is a schematic view of an image processing apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration example of an image processing unit, a controller unit, and the periphery thereof according to the present embodiment.

FIG. 3 is a block diagram showing a detailed configuration example of an R signal calculation unit of the color space compression unit of the present embodiment.

FIG. 4 is a flowchart showing an example of a color space compression procedure of the present embodiment.

FIG. 5 is a diagram illustrating an example of background level detection according to the present embodiment.

FIG. 6 is a diagram illustrating an example of color distribution detection according to the present exemplary embodiment.

FIG. 7 is a diagram illustrating an example of color distribution detection according to the present exemplary embodiment.

FIG. 8 is an R of the color space compression unit of the second embodiment according to the present invention.
It is a block diagram which shows the detailed structural example of a signal calculation part.

9 is a block diagram showing a modified example of the configuration shown in FIG. 2 or FIG.

[Explanation of symbols]

 104 main scanning address counter 106 CCD drive signal generating unit 107 analog / digital converter A / D 108 logarithmic converter LOG 109 UCR / masking processing unit 110 selector 112 selector 113 laser driver 114 photodetector 116 CPU unit 118 subscanning address counter 121 colors Spatial compression section 122 Variable magnification section 123 Sampling section

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G06T 5/00 H04N 1/46 G06F 15/64 400 C 15/66 310 15/68 310 A H04N 1 / 46 Z

Claims (9)

[Claims] 1. Input means for scanning an original image to input an image signal, and discriminating means for discriminating a color distribution and a background level of the original image based on the image signal obtained by the first scanning by the input means. And an image processing unit that performs color space compression and background level adjustment on the image signal obtained by the second scanning by the input unit based on the determination result by the determination unit. apparatus. 2. An input unit for scanning an original image to input an image signal, a calculating unit for calculating a plurality of coefficients based on the image signal obtained by the first scanning by the input unit, and the calculating unit. An image processing apparatus comprising: a color space compression unit that performs color space compression of an image signal obtained by the second scanning by the input unit by matrix conversion based on a plurality of coefficients calculated by the above. 3. The image processing apparatus according to claim 2, further comprising a forming unit that forms an image based on an image signal output from the color space compressing unit. 4. The image processing apparatus according to claim 1, further comprising a storage unit that samples and stores the image signal obtained by the first scanning by the input unit. 5. The image processing apparatus according to claim 2, wherein the compression unit adjusts a background level and a dark level in addition to the color space compression. 6. A first input unit for scanning a document image to input a first image signal, a second input unit for inputting a second image signal from an external device, and the first image signal. An image processing apparatus comprising: a color space compression unit that performs color space compression on the image processing apparatus; and a conversion unit that converts the image signal output from the color space compression unit into an output signal, wherein the second image signal Is input to the conversion means without passing through the color space compression means. 7. A determination step of determining a color distribution and a background level of the original image based on the image signal obtained by the first scanning of the input means for scanning the original image and inputting the image signal, and the input means. And a color conversion step of performing color space compression and adjustment of the background level on the basis of the discrimination result of the discrimination step with respect to the image signal obtained by the second scanning. 8. A calculating step of calculating a plurality of coefficients based on an image signal obtained by a first scanning of an input means for scanning an original image and inputting an image signal, and a plurality of calculating steps calculated in the calculating step. And a color space compression step of performing color space compression on the image signal obtained by the second scanning by the input means by matrix conversion based on the coefficient of. 9. A color space compression step of performing color space compression on an image signal input by first input means for inputting an image signal for scanning an original image, and an image output from the color space compression step. An image processing method comprising: a conversion step of converting a signal into an output signal, wherein the image signal input by the second input means for inputting the image signal from an external device is the above-mentioned without the color space compression step. An image processing method, characterized in that the image is input to a conversion step.