JPH0927905A - Image processing unit and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an output of an image at a high speed by reading an image signal and a characteristics signal in parallel so as to compensate the deterioration in the resolution of a character/line drawing in the case of emphasizing gradation and so as to compensate the deterioration in the gradation of the character/line drawing in the case of emphasizing resolution because no adaptive processing is applied to the image entered from an external device and the gradation and the resolution on an entire output image are fixed. SOLUTION: Upon receipt of an image signal from a host computer 101, a character/line drawing section 111 reads the image signal from an image memory 109 and generates a discrimination signal TEXT denoting whether or not a picture element forms a character/line drawing and stores the signal to the image memory 109. A PWM circuit 113 reads the image signal and its discrimination signal TEXT from the image memory 109 to revise PWM number of the image signal, based on the discrimination signal TEXT. Thus, the image is outputted depending on the feature of image.

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, for example, an image processing apparatus of an image processing system which operates as both a copying machine and a printer and a method thereof.

[0002]

2. Description of the Related Art Image reading means for reading an image and converting it into an image signal, and memory means for holding the obtained image signal,
An image output unit that outputs the held image signal,
The applicant has proposed an image forming apparatus that operates as a color copying machine.

Further, the above image forming apparatus and the host computer are connected via a controller, a color image created by the host computer is rasterized by the controller, and the raster image is held in a memory inside the controller, and then the image forming apparatus is used. The applicant has also proposed a system for outputting and operating as a color printer. This system operates as both a color copying machine and a color printer based on an instruction from the operator.

Further, when a document placed on the platen is copied and output, the character and line drawing parts are recognized and reproduced at a high resolution, and the gradation of other parts is emphasized rather than the resolution. The applicant has proposed a copying machine that adaptively reproduces data.

[0005]

However, the above-mentioned technique has the following problems. That is, in the above-described device or system, the image input from an external device such as a computer is not subjected to the adaptive processing as described above, so the gradation and resolution of the output image are fixed over the entire image, When the gradation is emphasized, the resolution of the character / line drawing portion is low, and when the resolution is emphasized, the gradation of the gradation portion is unavoidably low.

The present invention is for solving the above-mentioned problems, and is capable of recognizing a feature of an image input from an external device and adaptively outputting the image according to the feature. An object is to provide an apparatus and a method thereof.

Also, by recognizing the features of the input image,
Another object is to provide an image processing apparatus and method capable of adaptively outputting an image in accordance with its characteristics and outputting the image at high speed.

[0008]

The present invention has the following configuration as one means for achieving the above object.

The image processing apparatus according to the present invention generates a characteristic signal representing the characteristic of the image signal read from the storage means and the storage means for storing the input image signal, and stores the characteristic signal in the storage means. A feature detecting means for storing the image signal and its characteristic signal from the storing means and an output means for outputting the signal as a recording signal are provided, and the generating operation of the characteristic signal and the characteristic signal to the storing means. The operation of storing and the operation of reading the image signal and its characteristic signal from the storage means are performed substantially in parallel.

A storage means for storing the input image signal, and when the image signal is input from an external device,
An image signal is read from the storage means, a characteristic signal representing a characteristic of each pixel is generated, and stored in the storage means, a characteristic detection means, and an image signal and its characteristic signal are read from the storage means and recorded. And output means for outputting as a use signal.

An image processing apparatus for supplying an image signal to an image forming apparatus connected so as to be capable of bidirectional communication,
A first output means for outputting a plurality of color component signals; and a second output means for outputting a characteristic signal indicating characteristics of an image represented by the plurality of color component signals, wherein the plurality of color components A signal is output together with the characteristic signal at different timings for the same pixel.

According to the image processing method of the present invention, the image signal is read from the storage means for storing the input image signal,
A characteristic detection step of generating a characteristic signal representing the characteristic and storing the characteristic signal in the storage means; and an output step of reading the image signal and the characteristic signal thereof from the storage means and outputting the image signal as a recording signal. Generation processing of characteristic signals,
The processing for storing the characteristic signal in the storage means and the processing for reading the image signal and the characteristic signal from the storage means are performed substantially in parallel.

Further, when the image signal is input from an external device, the image signal is read from the storage means for storing the image signal, a characteristic signal representing the characteristic of each pixel is generated and stored in the storage means. And a characteristic detecting step for reading the image signal and its characteristic signal from the storage means,
And an output step of outputting as a recording signal.

Further, there is provided an image processing method for supplying an image signal to an image forming apparatus connected so as to be capable of bidirectional communication.
A first output step of outputting a plurality of color component signals, and a second output step of outputting a characteristic signal indicating the characteristics of the image represented by the plurality of color component signals, the plurality of color components The signal is output together with the characteristic signal at different timings for the same pixel.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image processing apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. Hereinafter, a full-color copying machine system will be described in detail as a preferred embodiment, but the present invention is not limited to this embodiment.

[Outline of Apparatus] FIG. 1 is a schematic view of a full-color copying machine system according to an embodiment of the present invention. 101 is a host computer, 102 is a controller, 103 is an image forming apparatus having a reader section and a printer section. .

The image forming apparatus 103 makes a color copy of a document image placed on a document table and also controls the controller 102.
Then, the color image sent from the computer 101 is output. Here, so-called DTP (Desk Top Publishing) application software runs on the host computer 101 to create or edit various documents and figures. The host computer 101 converts the created document or figure into data described in a page description language (PDL: Page Discription Language) such as Adobe PostScript, and the controller 102 through a connection cable 243.
Send to The controller 102 translates the PDL data sent from the host computer 102 and rasterizes it into an image signal for each pixel. The rasterized image signal is sent by the image forming apparatus 103 through the connection cable 242, and the image is output.

Here, the host computer 101, the controller 102, and the image forming apparatus 103 can perform bidirectional data communication with each other.

[Overview of Image Forming Apparatus] FIG.
It is a general view of 03.

When copying a document image as a copying machine: A document 202 placed on the platen glass 201 is illuminated by an illumination 203. Light reflected from the original 202 is reflected by the mirrors 204, 205, 2
After passing through 06, an image is formed on the CCD sensor 208 by the optical system 207. Further, the first mirror unit 210 including the mirror 204 and the illumination 203 is mechanically driven at a speed V by the motor 209, and the second mirror unit 211 including the mirrors 205 and 206.
Is driven at a speed of 1/2 V to scan the entire surface of the original 202.

The image processing section 212 processes the image information output from the CCD sensor 208 as an electric signal, temporarily holds it in an image memory 109 described later, and outputs it as a print signal. The print signal output from the image processing unit 212 is
It is sent to a laser driver (not shown) and drives four semiconductor lasers (not shown). One of the laser beams emitted by the four semiconductor lasers is scanned by the polygon mirror 213, passes through the mirrors 214, 215 and 216, and forms a latent image on the photosensitive drum 217. Each of the other laser lights also has a polygon mirror 21.
The latent image is formed on the photosensitive drum 221 through the mirrors 218, 219 and 220, the latent image is formed on the photosensitive drum 225 via the mirrors 222, 223 and 224, and the latent image is formed on the photosensitive drum 229 via the mirrors 226, 227 and 228.

In this way, the latent images formed on the respective photosensitive drums are respectively a developing device 230 for supplying yellow (Y) toner and a developing device 23 for supplying magenta (M) toner.
1, developing device 232 that supplies cyan (C) toner, black
It is developed by the developing device 233 which supplies the toner of (K).
The developed four-color toner image is transferred to a recording paper, and a full-color output image can be obtained.

The recording paper supplied from one of the recording paper cassettes 234 and 235 or the manual feed tray 236 is adsorbed on the transfer belt 238 via the registration roller 237 and conveyed. On the photosensitive drums 217, 221, 225, 229, toner images of respective colors have been developed in advance in synchronization with the paper feed timing.
The toner image is transferred onto the recording paper as the recording paper is conveyed.
The recording paper on which the four-color toner images have been transferred should be
Is separated from the fixing belt 2 and conveyed by the conveyor belt 239.
The toner is fixed by 40 and is discharged to the paper discharge tray 241.

The four photosensitive drums are arranged at equal intervals with a distance d, and the recording belt is conveyed at a constant speed V by the conveyor belt 238. Is driven.

When outputting an image sent from the host computer 101: An image signal output from the host computer 101 is directly transferred to the image memory 109 via the interface cable 242 via the controller 102 and then copied. An image is formed as in the case of machine operation.

[Flow of Image Signal] FIG. 3 is a block diagram showing the flow of the image signal.

Image processing unit 212 The CCD sensor 208 converts the image signal into image signals of three color components of red (R), green (G), and blue (B), which are output as digital signals. .

Reference numeral 112 denotes an input masking section, which converts the input R0G0B0 signal into the standard color space RG by the calculation shown in the following equation.
Convert to B signal. However, cij (i = 1,2,3 j = 1,2,
3) is a device-specific constant that takes into consideration various characteristics such as the sensitivity characteristic of the CCD sensor 208 and the spectral characteristic of the illumination 203.

Reference numeral 104 is a brightness / density conversion unit, which is a RAM or a ROM.
The lookup table is used to perform the operation shown in the following equation. C1 = -K ・ log (R / 255) M1 = -K ・ log (G / 255)… (2) Y1 = -K ・ log (B / 255) where K is a constant and the base of log is 10

An output masking / UCR unit 106 converts the M1C1Y1 signal into a YMCK signal which is the toner color of the image forming apparatus 103 by the calculation shown in the following equation. However, aij (i = 1,
2,3,4j = 1,2,3,4) is a device-specific constant in consideration of the tint characteristics of the toner. However, K1 = min (C1, M1, Y1)… (4)

From the above equations (1) to (4), the CCD sensor 208
The R0G0B0 signal output from is converted into a YMCK signal corresponding to the spectral distribution characteristic of toner and output.

On the other hand, reference numeral 105 denotes a character / line-drawing detecting section, which decides whether or not each pixel in the original image is a part of a letter or a line-drawing, and generates a decision signal TEXT. 107 is a compression / decompression section,
The C1Y1M1 image signal and the judgment signal TEXT are compressed to reduce the amount of information, and then stored in the memory 108 and the memory 108.
The read data is expanded and the C1Y1M1 image signal and the determination signal TEXT are reproduced.

The controller 102 110 is a CPU, which controls the entire controller 102 based on a program stored in a program ROM (not shown) or the like, and expands PDL data using a RAM or a buffer (not shown).

An image memory 109 stores the YMCK signal that matches the above-mentioned toner spectral distribution characteristic through the cable 242 and is read in synchronization with the image forming timing on the copying machine side to drive the above-mentioned semiconductor laser. Is sent to a PWM circuit 113 described later, which forms a PWM signal for Further, the image memory 109 not only holds the above YMCK signal, but also the RGB signal output from the host computer 101,
When holding the RGB signal output from the input masking unit 112 (in this case, the luminance / density conversion unit 104 and the output masking / UCR unit 106 are set with parameters for outputting the input signal as is (through)) There is.

Reference numeral 111 is a character / line drawing detection unit, the details of which will be described later.

[Copier Operation] In the system of this embodiment, the operation of the copier alone (hereinafter referred to as "copier operation")
, And "system operation" including the controller 102 exist, the operation of the copying machine will be described first.

In the case of a copier operation, the image signal output from the CCD sensor 208 is passed through the input masking section 112 and the brightness / density conversion section 104, and after being compressed by the compression / expansion section 107,
The character / line drawing determination unit 105 is written in the memory 108 as well.
The determination signal TEXT output from is also written in the memory 108 after being compressed by the compression / expansion unit 107. Then, the data read from the memory 108 is expanded by the compression / expansion unit 107, and in synchronization with the image forming timing of the copying machine,
It is sent to the laser driver through a PWM circuit 113 described later. FIG. 4 is a diagram showing an example of the timing of this copying machine operation.

In FIG. 4, the image signal is written in the memory 108 at the timing indicated by reference numeral 1101, and the reference numerals 1102-1105.
It is read at the timing shown by. The timing relationships indicated by reference numerals 1102-1105 are, as shown in FIG.
It has a V read start interval. Here, as described above, d is the interval between the four photosensitive drums arranged at equal intervals, and V is the transport speed of the transport belt 238. Needless to say, the read start timing of the Y stage indicated by reference numeral 1102 is later than the write start timing indicated by reference numeral 1101.

[System Operation] The system operation is roughly classified into a scan operation, a PDL expansion operation, a character / line drawing extraction operation, and a printout operation.

Scanning Operation This is an operation for fetching an image signal obtained by reading a document into the controller 102, and the image memory 109 holds RGB data or YMCK data. When reading RGB data, as described above, the brightness / density conversion unit 104 and the output masking / UCR unit
106 and through. In this way, RGB data and YM
CK data can be captured on a common line.

PDL expansion operation This is an operation of expanding the PDL data input from the host computer 101 into a full-color image and writing it in the image memory 109. This full-color image is developed as image data color-separated into four YMCK colors in accordance with the output characteristics (density characteristics, color reproduction characteristics) of the image forming apparatus 103.

Character / Line Drawing Extracting Operation This is an operation for reading out the full-color image data expanded and written in the image memory 109, and determining whether or not each portion of the full-color image is a character / line-drawing portion.
The character / line drawing detection unit 111 indicates whether or not each part of the full-color image read from the image memory 109 is a character / line drawing unit, and outputs a determination signal TEXT indicating the determination result to the image memory 109.
Write on

Printout Operation The image is output by the operation of reading the full-color image data and the determination signal TEXT stored in the image memory 109 in synchronization with the rotation of the four photosensitive drums and sending them to the PWM circuit 113 described later. .

Operation Timing FIG. 5 is a diagram showing a timing example of this system operation, in which the scan operation or the PDL expansion operation is performed in the section indicated by reference numeral 1201, and at the same time, the writing operation to the image memory 109 is performed. The image data written in the image memory 109 is
At the same time as the character / line drawing is extracted in the section indicated by reference numeral 1202, it is read at the timing shown by reference numerals 1203 to 1206.
The timing relationships indicated by reference numerals 1203 to 1206 each have a read start interval of time d / V, as shown in the figure.

Here, what is characteristic is that the character / line drawing detection unit 111 generates a determination signal TEXT, an operation of recording the generated determination signal TEXT in the image memory 109, full-color image data and its determination signal TEXT. Is to be performed simultaneously (in parallel), and the processing speed can be increased as compared with the case where these operations are sequentially performed. Note that the simultaneous processing control of these operations is performed by the CPU 110. That is, the CPU 110 can realize the writing and reading operations for the image memory 109 in a time division manner.

[Character / Line Drawing Detecting Section] FIG. 6 is a block diagram showing a configuration example of the character / line drawing detecting section 105.
5 generates a determination signal TEXT that extracts a character and a line drawing portion from an RGB image signal obtained by reading an original, and outputs "1" when the pixel constitutes a character or a line drawing portion, and "0" otherwise. .

In FIG. 6, reference numeral 601 denotes an ND signal generator, which generates an ND signal which is a lightness signal in consideration of human visibility characteristics from the full-color RGB image signal by the product-sum calculation shown in the following equation. Here, d1, d2, and d3 are constants in consideration of human luminosity characteristics.

A character / line drawing determination unit 602 extracts a character / line drawing portion from the lightness signal ND and generates "1" when the pixel constitutes a character or line drawing portion, and "0" otherwise. . Since this type of circuit is known, a detailed description thereof will be omitted.

Similarly, FIG. 7 is a block diagram showing a configuration example of the character / line drawing detection unit 111. The character / line drawing detection unit 111 extracts a character and a line drawing portion from the YMCK image signal, and the pixel concerned is a character or a line drawing. A determination signal TEXT is generated which is "1" when the part is configured, and is "0" otherwise.

In FIG. 7, reference numeral 701 denotes an ND signal generator, which approximately generates an ND signal which is a lightness signal considering human visibility characteristics from a full-color YMCK image signal by a product-sum operation shown in the following equation. However, e1, e2, e3, and e4 are constants that take human visibility characteristics into consideration.

The character / line drawing determination unit 602 is the same as the character / line drawing determination unit 602 shown in FIG.

[Judgment Signal TEXT] FIG. 8 is a diagram for explaining the judgment signal TEXT, in which 401 represents an example of a document to be read or an image to be printed out, and 402 represents the judgment signal TEXT in the image 401 in a two-dimensional manner. Is the image shown in. That is,
The character / line drawing portion in the image 401 is shown in “black” in the image 402, and the others are shown in “white”. 403 for image 402
In an image obtained by enlarging a part of the above, the pixels indicated by a black circle indicated by reference numeral 404 are pixels forming the character / line drawing portion, and the TEXT signal thereof becomes '1'. On the other hand, the pixels marked with a circle 405 are pixels that make up other than the character / line drawing, and the TEXT signal thereof is “0”.

[Image Memory] FIG. 9 is a diagram for explaining the structure of data stored in the image memory 109 and how to read it.
501 shows an example of an address map in the image memory 109. For example, yellow (Y) image data 502, magenta (M) image data 503, cyan (C) image data 504,
Black (K) image data 505 is attached to each pixel.
It has 8 bits of information. Also, the judgment signal TEXT data 5
06 has 1-bit information per pixel.

Reference numeral 507 conceptually shows how each of the above data is read. That is, Y image data 502
M image data 503 in synchronization with the image formation on the photosensitive drum 217.
Is the C image data 504 in synchronization with the image formation on the photosensitive drum 221.
Is synchronized with the image formation on the photosensitive drum 225 and the K image data 505
Are read in synchronization with the image formation on the photosensitive drum 229. Further, the data 506 of the determination signal TEXT is read simultaneously in four systems (in parallel) in synchronization with all the four photosensitive drums.

[PWM Circuit] FIG. 10 is a block diagram showing a configuration example of the PWM circuit 113.

In FIG. 10, 901 is a PWM for yellow (Y)
In the circuit, the yellow (Y) digital image signal and the determination signal TEXT in synchronization with the digital image signal are input, and an analog signal to be sent to the laser driver that drives the yellow (Y) semiconductor laser is generated. 902 is a PWM circuit for magenta (M), 9
03 is a PWM circuit for cyan (C), 904 is a PWM circuit for black (K)
In the circuit, the digital image signal of each color component and the determination signal TEXT are input in synchronization with the digital image signal, and an analog signal to be sent to the laser driver that drives the semiconductor laser is generated.

FIG. 11 is a block diagram showing a configuration example of the PWM circuit for each color component, and the circuit configuration is the same regardless of the color component.

In FIG. 11, 1001 is a D / A converter,
The input digital image signal is converted into an analog image signal. Reference numeral 1002 denotes a triangular wave generator for an image that emphasizes gradation, and generates, for example, a triangular wave having a two-pixel cycle. Reference numeral 1003 denotes a triangular wave generation circuit for an image, which places importance on resolution, and generates a triangular wave of one pixel cycle. A selector 1004 selects and outputs one of two triangular waves having different periods based on the determination signal TEXT. That is, the selector 1004 selects the number of PWM lines (resolution) based on the determination signal TEXT. A comparator 1005 compares the analog image signal output from the D / A converter 1001 with the triangular wave selected by the selector 1004.

With the above configuration, in the character and line drawing parts, the triangular wave of one pixel cycle which emphasizes resolution is compared with the analog image signal, while in the parts other than the character and line drawing parts, the two pixel cycle which emphasizes gradation is emphasized. The triangular wave and the analog image signal are compared, and a pulse signal subjected to pulse width modulation (PWM) is output. This pulse signal is sent to a laser driver (not shown).

The period of the triangular wave which emphasizes gradation is not limited to two pixels, but may be set to a three-pixel period or a four-pixel period in relation to the resolution of the image forming section.

FIG. 12 is an example of a timing chart in the PWM circuit. The upper part of the figure shows the PWM timing when the gradation is emphasized, and the output 801 of the D / A converter 1001 and the triangular wave 802 in two pixel units are compared. Then, the pulse signal 803 is output from the comparator 105. On the other hand, the lower part of the figure shows the PWM timing when the resolution is important, and the D / A converter 10
The output 804 of 01 is compared with the triangular wave 805 for each pixel, and the pulse signal 806 is output from the comparator 105.

In practice, a determination signal TEXT indicating whether each part of the image to be output is a character / line drawing part where the resolution is important or a part other than the character / line drawing where the tone is important is
Since the pulse signals 803 and 806 are adaptively switched and output, preferable image formation is performed.

As described above, in any case of an image read from a document or an image generated by a computer, it is determined whether or not each pixel is a pixel forming a character / line drawing portion, and the resolution is emphasized. By adaptively selecting for each pixel whether to emphasize the gradation or
It is possible to perform image output with emphasis on resolution in the line drawing portion and emphasis on gradation in other areas. Moreover, such an operation can be realized not only for the image read by the scanner but also for the input image from the host computer.

Furthermore, since the generation of the determination signal of the character / line drawing portion, the operation of recording the generated determination signal in the image memory, and the reading of the image data and the determination signal are performed simultaneously (in parallel), these The processing can be speeded up and an image can be output at high speed as compared with the case of sequentially performing the above operation.

[0065]

Other Embodiments Even when the present invention is applied to a system composed of a plurality of devices (for example, host computer, interface, printer, reader, etc.), one device (for example, copying machine, facsimile machine, etc.) ).

The present invention is achieved by supplying a storage medium storing a software program for achieving the present invention to a system or apparatus, and the system or apparatus reading and executing the program stored in the storage medium. It goes without saying that it can be applied to cases where As a storage medium for supplying the program, for example, a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a magnetic tape, a non-volatile memory card, a ROM or the like can be used.

Further, in the controller 102, the characteristic signal is stored in the image memory 109, but another memory may be provided for the characteristic signal.

The feature of the image signal represented by the feature signal is not limited to the character / line image, but may be a feature such as a black character / line image or a photograph / halftone dot.

[0069]

As described above, according to the present invention,
It is possible to provide an image processing apparatus and method for recognizing a feature of an image input from an external device and adaptively outputting an image according to the feature.

Further, by recognizing the features of the input image,
It is possible to provide an image processing apparatus and method for adaptively outputting an image according to its characteristics and outputting the image at high speed.

[Brief description of drawings]

FIG. 1 is a schematic view of a full-color copying machine system according to an embodiment of the present invention,

FIG. 2 is a schematic view of the image forming apparatus shown in FIG.

FIG. 3 is a block diagram showing the flow of an image signal,

FIG. 4 is a diagram showing a timing example in a copying machine operation;

FIG. 5 is a diagram showing a timing example in system operation;

6 is a block diagram showing a configuration example of a character / line drawing detection unit shown in FIG.

7 is a block diagram showing a configuration example of a character / line drawing detection unit shown in FIG.

FIG. 8 is a diagram for explaining a determination signal TEXT.

9 is a diagram for explaining a structure of data stored in the image memory shown in FIG. 3 and a method of reading the data;

FIG. 10 is a block diagram showing a configuration example of a PWM circuit,

FIG. 11 is a block diagram showing a configuration example of a PWM circuit for each color component,

FIG. 12 is an example of a timing chart in the PWM circuit.

Claims (12)

[Claims] 1. Storage means for storing an input image signal, feature detection means for generating a feature signal representing the feature from the image signal read from the storage means, and storing the feature signal in the storage means. An output unit for reading out the image signal and its characteristic signal from the storage unit and outputting it as a recording signal; an operation of generating the characteristic signal; an operation of storing the characteristic signal in the storage unit; An image processing apparatus, wherein an operation of reading a signal and its characteristic signal from the storage means is performed substantially in parallel. 2. Storage means for storing an input image signal, and when the image signal is input from an external device, the image signal is read out from the storage means and a characteristic signal representing a characteristic of each pixel is generated. An image processing apparatus comprising: a characteristic detecting means for storing in the storage means; and an output means for reading out an image signal and its characteristic signal from the storage means and outputting as a recording signal. 3. The operation of generating the characteristic signal, the operation of storing the characteristic signal in the storage means, and the operation of reading the image signal and the characteristic signal from the storage means are performed substantially in parallel. The image processing device according to claim 2, wherein 4. A conversion means for converting the image signal into a recording signal that emphasizes resolution or a recording signal that emphasizes gradation, based on the characteristic signal. The image processing device according to claim 3. 5. The image processing apparatus according to claim 1, wherein the characteristic signal represents whether or not each pixel forms a character / line drawing. 6. The conversion means converts an image signal of pixels forming the character / line drawing into a recording signal with emphasis on resolution based on the characteristic signal, and an image of pixels forming other than the character / line drawing. 6. The image processing apparatus according to claim 5, wherein the signal is converted into a recording signal that emphasizes gradation. 7. An image processing apparatus for supplying an image signal to an image forming apparatus connected so as to be capable of bidirectional communication, comprising: first output means for outputting a plurality of color component signals; and the plurality of color components. A second output unit that outputs a characteristic signal indicating the characteristic of the image represented by the signal, and outputs the plurality of color component signals together with the characteristic signal at different timings for the same pixel. Image processing device. 8. The image processing according to claim 7, wherein the image forming apparatus includes a plurality of image forming units, and each of the plurality of color component signals corresponds to each of the image forming units. apparatus. 9. The image processing apparatus according to claim 7, wherein the second output unit can output the characteristic signals in parallel at different timings. 10. A feature detecting step of reading an image signal from a storage means for storing an input image signal, generating a feature signal representing the feature and storing the feature signal in the storage means, and an image signal from the storage means. An output step of reading the characteristic signal and outputting it as a recording signal, the generation processing of the characteristic signal, the processing of storing the characteristic signal in the storage means, the image signal and the characteristic signal. An image processing method, wherein the process of reading from the storage means is performed substantially in parallel. 11. When an image signal is input from an external device, the image signal is read from a storage unit that stores the image signal, a characteristic signal representing a characteristic of each pixel is generated, and stored in the storage unit. And an output step of reading the image signal and its characteristic signal from the storage means and outputting the image signal as a recording signal. 12. An image processing method for supplying an image signal to an image forming apparatus connected in a bidirectionally communicable manner, comprising: a first output step of outputting a plurality of color component signals; A second output step of outputting a characteristic signal indicating the characteristics of the image represented by the signal, wherein the plurality of color component signals are output together with the characteristic signal at different timings for the same pixel. Characterized image processing method.