JPH09284548A - Picture processor and method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a picture processor and a picture processing method for outputting a picture where pictures different in characteristics such as a character, a line and a continuous gradation picture coexist with high difinition through the use of comparatively few memories. SOLUTION: A PDL(page description language) interpreter 102 executes a raster image processing on picture information described by the inputted PDL and stores obtained picture data in a picture memory 103. A CPU 104 refers to picture data stored in the picture memory 103, discriminates the types of the pictures for respective picture elements and stores discrimination codes in a code memory 105. Then, picture data which is stored in the picture memory 103 is read and the discrimination code corresponding to the picture data is read from the code memory 105. Different binarization processings are executed on picture data which are are by binarization circuits 106 and 107. A selector 108 selects the output of the binarization circuit 106 or 107 in accordance with the discrimination code read from the code memory 105 and transmits selected picture data to a printer 109.

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 and a method thereof for outputting an image with high quality.

[0002]

2. Description of the Related Art In the case of outputting a hard copy of a document created / edited by a computer, the procedure is generally as follows. That is, the document information is once replaced by a command group describing image information by a printer driver or the like running on the computer, and the command group is transferred to the command interpreter of the image output device. The command interpreter creates a raster image according to the received command group and sends the raster image to the image output unit.

Such a command system for describing image information is called a page description language (PDL), and a typical one is P
Examples include ostScript (registered trademark) and Capsl (registered trademark).

FIG. 9 shows the configuration of a system using PDL.
In FIG. 9, 801 is a host computer that instructs hard copy output, 802 is a PDL interpreter, 803 is an image memory, 804 is a binarization circuit, and 805 is a printer. 806 is PDL
A controller that controls the interpreter 802, the image memory 803, the binarization circuit 804, and the printer 805.

The host computer 801 transfers data such as a hard copy output document as PDL data to the PDL interpreter 802. The PDL interpreter 802 converts the PDL data received from the host computer 801 into raster image data and writes it in the image memory 803.

The interpreter 802 is a host computer 8
When all the PDL data sent from 01 is converted into raster image data, the controller 806 is notified of the end of processing. The controller 806 is a PDL interpreter 802
Upon receiving a processing end notification from the printer, the raster image data stored in the image memory 803 is transferred to the printer 805, and a hard copy image is output.

Here, since the data stored in the image memory 803 generally has information of about 8 bits (256 gradations) per pixel, the printer 805 is white for each pixel like an ink jet system. If only the black binary can be expressed, the data stored in the image memory 803 cannot be directly transferred to the printer 805. In that case, the controller 806 converts the data stored in the image memory 803 to the binarization circuit 804.
Is converted into binary information by and then transferred to the printer 805.

Next, let us consider a case where the system shown in FIG. 9 outputs a hard copy image such as that shown in FIG.

In FIG. 10, 901 is a continuous tone image obtained by scanning a silver halide photograph with a scanner, 902 is character information created using a word processor, and 903 and 904 are created using a graph creating function of spreadsheet software. It is a pie chart and a line chart.

When images having these different characteristics are mixed in one image, the binarization circuit 804 shown in FIG. 9 is used.
Converting 8-bit data to 1-bit data with the following causes the following problems.

(1) 128 or more, which is an intermediate value of 256 gradations, is set to "1".
Then, if the value of 127 or less is simply binarized as '0', the gradation property of the continuous gradation image part is lost, and 256
In a pie chart in which segments are represented by painting different levels in the gradation, it is difficult to distinguish the segments and information is lost.

(2) If a pseudo halftone binarization method such as the error diffusion method is used, the inconvenience as described in the above (1) is eliminated, but conversely, black dots are formed around the line of a character or line graph. The lines are blurred and unsightly.

[0013] Such an inconvenience is not the same not only in an ink jet printer for forming a binary image, but also in a printer for forming a binary image by another method or a printer having a reproducibility of two or more values. That is the same problem.

[0014]

The following methods are available as methods for solving the above inconveniences.

(A) Two kinds of bitmap memories are prepared for binary images and continuous tone images, and character and line drawing data suitable for simple binarization are written in the binary image memory, and pseudo intermediate The continuous tone image data suitable for binarization is written in the continuous tone image memory. At the time of output, the data stored in each memory is binarized by a method suitable for each memory, combined, and transferred to the printer.

(B) An image area determination circuit is provided in the preceding stage of the binarization circuit, and it is determined for each pixel whether the data input to the binarization circuit is continuous tone image data or character / line drawing data, and The binarization method of the binarization circuit is switched on a pixel-by-pixel basis according to the determination result.

However, even if such a method is adopted, the following problems remain.

In method (A), the type of image data (character / line image or continuous tone image, etc.) can be known by referring to the PDL data, and accordingly, the storage location of the raster image data can be switched. It is possible. But PD
Since the L interpreter needs to have such a function, the PDL interpreter must be modified.

Further, since the method (B) performs a well-known image area discrimination process which refers to a density histogram, a density gradient between neighboring pixels, etc., to raster image data converted from PDL data, a judgment error is likely to occur. For example, if the continuous tone image portion is determined to be the character portion, only the erroneously determined tone image portion is simply binarized and an unnatural image is output.

The present invention is intended to solve the above-mentioned problem, and makes it possible to improve the quality of an image in which images having different characteristics such as characters and line images and continuous tone images are mixed by using a relatively small memory. An object of the present invention is to provide an image processing device capable of outputting and a method thereof.

Another object of the present invention is to provide an image processing apparatus and method capable of recognizing a feature of an image input from an external device and adaptively outputting the image according to the feature. .

Further, 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.

[0023]

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

The image processing apparatus according to the present invention expands the input image information described in the page description language, and stores the expanded image data of each pixel in the first storage means, and the first storage means. A discriminating means for discriminating the characteristics of the image for each pixel with reference to the image data stored in the storing means, and storing a discrimination code representing the discrimination result in the second storing means, and the first storing means. Read out the image data stored in the second storage means, and read out the discrimination code corresponding to the image data for each pixel from the second storage means; A processing unit for selectively performing different image processing on the image data according to the discrimination code read from the second storage unit by the reading unit; and a compression unit for compressing the image data, Serial first storage means is characterized by storing the image data compressed.

Also, the first storage means for storing the input image signal, and when the image signal is input from an external device, the image signal is read out from the first storage means and the characteristics of each pixel are determined. A characteristic detecting means for generating a characteristic signal to be stored and storing it in the second storing means, and an output means for reading out the image signal and its characteristic signal from the first and second storing means and outputting as a recording signal. And compression means for compressing image data, wherein the first storage means stores the compressed image data, the generation operation of the characteristic signal, and the characteristic signal are stored in the second storage means. The operation and the operation of reading the image signal and its characteristic signal from the first and second storage means are performed substantially in parallel.

In the image processing method according to the present invention, a step of expanding the input image information described in the page description language and storing the expanded image data of each pixel in the first storage means, A discriminating step of discriminating the characteristics of the image for each pixel with reference to the image data stored in the storing means, and storing a discrimination code representing the discrimination result in the second storing means; and the first storing means. Read out the image data stored in, and read out the discrimination code corresponding to the image data for each pixel from the second storage means, and read out from the first storage means in the read step. A processing step for selectively performing different image processing on the image data according to the discrimination code read from the second storage means in the reading step, and a compression step for compressing the image data. Tsu and a flop, and wherein the storing the image data compressed in said first storage means.

Further, a storing step of storing the input image signal in the first storage means, and when the image signal is input from an external device, the image signal is read out from the first storage means and each pixel thereof is read. Characteristic detecting step of generating a characteristic signal representing the characteristic of the first storage means and storing it in the second storage means, and reading out the image signal and the characteristic signal from the first and second storage means and outputting it as a recording signal. And a compression step of compressing the image data, storing the compressed image data in the first storage means, generating the characteristic signal, and transmitting the characteristic signal to the second storage means. The operation of storing and the operation of reading the image signal and its characteristic signal from the first and second storage means are performed substantially in parallel.

[0028]

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.

[0029]

First Embodiment [Configuration] FIG. 1 is a block diagram showing a configuration example of an image processing system according to an embodiment of the present invention.

In FIG. 1, reference numeral 101 denotes a host computer, which generates PDL data (command) that constitutes an output image. 102 is the PD sent from the host computer 101
A PDL interpreter interprets L data and expands it into raster image data of each pixel, and 103 is an image memory for storing the raster image data. Reference numeral 104 denotes a CPU, which refers to the data stored in the image memory 103 at the time when the processing of the PDL interpreter 102 is completed, and in pixel units, determines whether the pixel of interest is a character / line drawing portion or a continuous tone image portion, The code information that is the determination result is written in the code memory 105 on a pixel-by-pixel basis.

The ROM 104a is a memory in which an image processing program executed by the CPU 104, a control program and various data are stored in advance, and the RAM 104b is a memory used as a work memory by the CPU 104.

Reference numerals 106 and 107 respectively denote a binarization circuit for outputting a hard copy of the raster image data stored in the image memory 103 by the printer 109. The binarization circuit 106 is a simple binarization based on a predetermined threshold value. A simple binarization circuit for binarization, a binarization circuit 107 is a well-known error diffusion binarization circuit for binarizing continuous tone image data by pseudo halftone processing.

Reference numeral 108 denotes a selector which selects one of the outputs of the two binarization circuits 106 and 107 and outputs it to the printer 109. The selection is performed by using the code information stored in the code memory 105 to select a pixel. It is done in units.

The printer 109 is a printer that forms a binary image, such as an ink jet printer. The output destination of the image data processed by the image processing system of the present embodiment is not limited to the printer, and may be a monitor such as a ferroelectric liquid crystal display (FLCD).

[Operation] The operation of this embodiment having the above configuration will be described with reference to the flowchart of FIG.
The process shown in FIG. 2 is executed by the CPU 104. Further, in this embodiment, the data written in the image memory 103 is 8 bits per pixel (0 to 255).
It is assumed to be expressed by.

First, in step S1, from the image memory 103, 3 × 3 pixels a1 to a9 centered on the target pixel a5 shown in FIG.
Of the target pixel a5 is substituted into the variable ac in step S2.

Next, in step S3, the work variables are initialized. That is, an array variable exist (j) (j = 0 to ~ for counting the number of data of different levels included in 3 × 3 pixels).
255) is cleared to 0, and the amount of data change in the 3 × 3 pixel area ied
The variable iemax for obtaining the maximum value of g is cleared to 0, and the loop variable i is initialized to 1.

Subsequently, the loop variable i is incremented in step S4, and | ai-ac | is calculated to calculate the variable i in step S5.
Substitute in edg. If iedg> iemax, substitute iedg in iemax and 1 in exist (ai). By the determination in step S6, the processes of steps S4 and S5 are repeated for i = 1 to 9. By the above processing, 3x3 pixels centered on the target pixel a5
The maximum absolute value of the differences between the image data items a1 to a9 is obtained.

Next, in step S7, the total sum icnt of exist (j) is obtained. icnt indicates the number of different data that appear in the 3 × 3 pixel area.

In the following step S8, the obtained feature quantity iemax,
Based on icnt, it is determined whether it is a character / line drawing area or a continuous tone image area. If the condition of expression (1) is true, the pixel of interest a
Assuming that 5 is in the character / line drawing area, proceed to step S9,
After generating "1" as the judgment code icode, step S1
Proceed to 1. icnt <4 and iemax> 128… (1)

On the other hand, if the expression (1) is not satisfied, it is determined that the pixel of interest a5 is in the continuous tone image portion, and step S10 is performed.
Then, after generating "0" as the determination code icode, the process proceeds to step S11. The icode is written in the code memory 105 at a position corresponding to the pixel a5.

Subsequently, in step S11, it is checked whether or not the above determination has been executed for all pixels. If the determination for all pixels has not been completed, the process returns to step S1 to process the next pixel. . When the determination of all the pixels of the raster image data stored in the image memory 103 is completed, the determination code corresponding to each pixel is written in the code memory 105, and the CPU 104 ends the process.

By executing the above processing, both the code information (judgment code icode) and the raster image data are complete. The CPU 104 reads out the raster image data from the image memory 103 for each pixel and sends the icode stored in the code memory 105 to the selector 108 so that either the simple binarization circuit 106 or the error diffusion binarization circuit 107 is provided. Is selected to perform binarization according to the type of image data.

More specifically, the data stored in the image memory 103 is sequentially read from the beginning and binarized in parallel by both the binarization circuits 106 and 107. On the other hand, the icode stored in the code memory 105 is also read at the same time and input to the selector 108 as a select signal. And ico
When de is “1”, the output of the simple binarization circuit 106 is selected and sent to the printer 109. When icode is “0”, the output of the error diffusion binarization circuit 107 is selected and sent to the printer 109.

In this way, the printer 109 can obtain high-quality hard copy output that matches the characteristics of various images mixed in the image.

[Details of Judgment Processing] FIG. 4 is a diagram showing an example of an image in which images having various characteristics are mixed. Figures 5A to 5E show
FIG. 4 is a diagram showing a state of determination in each area of FIG.
The values of the image data in the 3 × 3 pixel area indicated by 301 to 305 and the determination result are shown.

As shown in FIG. 5A, in the pixel area 301 of the continuous tone image portion, the probability that different data will appear in 3 × 3 pixels is high (icnt = 7), and the distance between the target pixel and the peripheral pixels is high. Since the data difference of (1) is small (iemax = 8), it does not apply to the expression (1) and is determined to be a continuous tone image area.

On the other hand, as shown in FIGS. 5B, 5C and 5E,
In areas of characters and line drawings such as the image areas 302, 303, and 305, the probability of different data appearing is low, and since the data difference between the pixel of interest and peripheral pixels is very large,
It is determined to be a character / line drawing area by applying the expression (1).

Further, like the image area 304 shown in FIG. 5D,
Although only 80 data appear and icnt is small, if the data difference between the pixel of interest and the surrounding pixels is small, it is determined to be a continuous tone image area, and pseudo halftone binarization is performed.

As described above, according to this embodiment,
When a hard copy output of an image in which images of various characteristics are mixed by a binary printer is performed, the image types are accurately separated, and image processing according to the types is performed.
A high-quality hard copy image can be obtained.

Further, in the above description, an example is described in which an image is processed by discriminating and separating an image into two types, that is, a character / line drawing region or a continuous tone region, but the image is further divided into many types. Then, it is possible to perform processing adapted to each type on the image.

Further, in the above description, an example in which the determination of the image type is executed by software has been described, but hardware that realizes the same function may be used.

[0053]

[Modification of First Embodiment] FIG. 24 is a block diagram showing a modification of the first embodiment, in which the same functional parts as those in FIG. 1 are designated by the same reference numerals.

In FIG. 24, 103a is a compression circuit, 103b is a selector, 103c is a decompression circuit, and 103d is a selector. In this embodiment, there are two operation modes, "compression mode" and "non-compression mode". ing. Switching between the two modes is CP
This is performed by switching the control signals of the selectors 103b and 103d by U104.

That is, in the present embodiment, the image data converted into the raster image data by the PDL interpreter 102 is compressed in the compression mode by the compression circuit 103a and then written and held in the image memory 103 in the compression mode. It Further, in the non-compressed mode, the data is not compressed but is written and held in the image memory 103 as it is.

Further, the CPU 104 refers to the image information stored as image data for each pixel in the image memory 103, and in pixel units, the pixel of interest is included in the character / line drawing area or in the continuous tone area. It is determined whether it is included, and the code information (icode) that is the determination result is written in the code memory 105.
However, if the CPU 104 is in uncompressed mode,
The above determination is performed using the image data read from 103 as it is, but in the case of the compression mode, after decompressing the compressed data read from the image memory 103 by the decompression circuit 103c,
The above judgment is performed.

During image formation in the compressed mode, the compressed data read from the image memory 103 is decompressed by the decompression circuit 103c and then sent to the binarization circuits 106 and 107.
Also, the image memory is
The image data read from 103 is directly converted to the binarization circuit 106.
And sent to 107.

The compression / expansion algorithm used in the compression circuit 103b and the expansion circuit 103c is arbitrary and is not particularly limited. For example, the so-called JPEG (Joint Photographic Ex
block coding using orthogonal transformation such as perts group), or DPCM (Differential Differential) using the difference value for each pixel.
Pulse Code Modulation) encoding or the like can be used. Further, in the present embodiment, an example in which the image data is compressed / decompressed by hardware has been shown, but it may be performed by software.

According to this embodiment, the image memory can be efficiently used by providing the compressed mode and the non-compressed mode and appropriately using them properly. For example, when the above compression is a lossy compression method, the amount of information can be suppressed by the compression mode, and the deterioration of the reproduced image can be suppressed by the non-compression mode.

[0060]

Second Embodiment FIG. 6 is a block diagram showing an example of the arrangement of an image processing system according to the second embodiment of the present invention.

In the second embodiment, as the printer 109, the laser beam modulated by the image data is scanned by the polygon mirror rotating at a high speed to form an electrostatic latent image on the photosensitive drum. A laser beam printer that forms a multi-valued image by developing toner with toner is used. In addition,
The same components as those in the first embodiment described above are designated by the same reference numerals, and detailed description thereof will be omitted.

Similarly to the first embodiment, when the CPU 104 writes the code information icode corresponding to the raster image stored in the image memory 103 into the code memory 105, the image memory 10
Image data is read in order from 3 and code memory 1
The icode is read from 05 and sent to the printer 109. Printer 10
The icode input to 9 is input to the selector 409 as a selection signal, and the image data is converted by the DA converter 406 into a corresponding analog signal.

On the other hand, the two triangular waveform generators 407 and 408 respectively have triangular waves 501 and 502 having different periods as shown in FIG.
Occurs. The selector 409 selects one of the two triangular waves 501 and 502 according to the input icode. The selector 409 selects a triangular wave 501 having a short cycle when icode is “1” (character / line drawing area), and selects a triangular wave 502 having a long cycle when icode is “0” (continuous tone image area).

The triangular wave selected by the selector 409 is
An analog image signal input to one input terminal of the comparator 410 and input to the other input terminal of the comparator 410 by the DA converter 406 (5 shown in FIG. 7).
03) and pixel by pixel. As a result, the pulse width modulation signal (Fig.
504) shown in 7 is obtained. This pulse width modulation signal is input to the laser driver 411 and modulates the light emission time of the semiconductor laser device 412. The modulated laser light output from the semiconductor laser element 412 is irradiated onto a photosensitive drum (not shown) of the printer engine 413 to form an electrostatic latent image, and an image is output through a peripheral electrophotographic process.

As described above, according to the second embodiment,
In the character / line drawing area, the triangular wave having a short cycle is used to control the laser emission pulse width of the semiconductor laser device, and in the continuous tone image area, the triangular wave having a long cycle is used to control the laser emission pulse width. As a result, the shorter the pulse width cycle of the laser light, the higher the resolution of the output image, but the lower the gradation reproducibility. Conversely, the longer the pulse width cycle of the laser light, the lower the resolution of the output image. A high-quality hardcopy image can be obtained when a multivalued printer outputs a hardcopy output of an image in which images having different characteristics are mixed by utilizing the characteristic that the adjustment reproducibility is increased.

[0066]

[Modification of Second Embodiment] FIG. 25 is a block diagram showing a modification of the second embodiment. This modification has the configuration shown in FIG.
Similar to the modification of the first embodiment, a function of selecting a compression mode and a non-compression mode is added. Therefore, the figure
The difference from 6 is the same as the modified example of the first embodiment described with reference to FIG. 24, and thus the description thereof will be omitted.

[0067]

Third Embodiment FIG. 8 is a block diagram showing an example of the arrangement of an image processing system according to the third embodiment of the present invention. In addition, in the same configuration as the first and second embodiments described above,
The same reference numerals are given and detailed description thereof is omitted.

In the third embodiment as well, a laser beam printer is used as the printer 109, but the laser beam printer of this embodiment can output a full-color image. Therefore, the color image data (raster image data of three surfaces of R, G, and B) is stored in the image memory 103, and the image formation by the semiconductor laser device 412 is
Color component images for four colors of yellow (Y), magenta (M), cyan (C), and black (K) are formed in a frame sequential manner, and a color hard copy image is output.

As will be described later in detail, the code memory 105 in this embodiment must have a storage capacity of at least 2 bits per pixel.

In FIG. 8, reference numerals 601 to 604 are color processing circuits for generating Y, M, C, K data from R, G, B color image data, and 601 is an R, G, B luminance signal for density signal C. , M, Y, which is a logarithmic conversion circuit for converting the following equation. c = -logR m = -logG… (2) y = -logB However, the base of logarithm is 10

Reference numeral 602 is a black signal extraction circuit for extracting the minimum value of the three density signals to obtain the black signal K, and executes the following equation. k = Min (c, m, y)… (3)

Reference numerals 603 and 604 denote the c, m, y, k signals obtained above by the following matrix conversion for C, M, and
This is a so-called masking conversion circuit that converts Y and K signals.

The reason why there are two masking circuits is that different conversion coefficients bij are set for both, and the output signals of both are switched by the selector 605 by the method described later and output to the printer 109.

The detailed operation of the third embodiment will be described below.

FIG. 11 is a flow chart showing the image area discrimination processing in this embodiment.

Similar to the first embodiment, the CPU 104 writes the code information icode corresponding to the raster image stored in the image memory 103 in the code memory 105 in steps S1 to S10. The determination of the character / line drawing area or the continuous tone image area at this time can be performed by performing the same processing as that of the first embodiment on the G (green) image data stored in the image memory 103. .

Next, the CPU 104, in step S12,
For a pixel (icode = 1) determined as a line drawing area, the image data of the R, G, B three sides of the pixel is read, and the saturation information W is obtained by the following equation. W = | R-G | + | G-B | + | B-R |… (5)

Then, in steps S13 and S14, if W is equal to or less than the predetermined threshold value TH, the ic corresponding to the pixel
Rewrite the value of ode from 1 to 2. This is because that W is equal to or less than TH means that the R, G, and B values of the pixel of interest are close to each other, and that they are close to an achromatic color. As a result, the pixel for which 2 is written in icode is in the achromatic (black) character / line drawing area.

Therefore, as a coefficient to be set in the masking circuits 603 and 604, a coefficient in which the color reproducibility of the image to be reproduced is emphasized is set in the masking circuit 603, and the masking circuit 604 is set.
Is set to a coefficient such that the output Y, M, and C signals are always 0 and only the black signal K has a value. Then, the selector 605 selects the output of the masking circuit 604 when icode is 2, and selects the output of the masking circuit 603 otherwise. As a result, the image data of the pixels in the black character / line drawing area is output in a single black color, and the image data in the other image areas is output with color reproducibility faithful to the color of the original image data.

The image data output from the selector 605 is input to the printer 109 as in the second embodiment,
It is converted into a corresponding analog signal by the DA conversion circuit 406 and input to one input terminal of the comparator 410.
The triangular wave selected by the selector 409 according to icode is input to the other input terminal of the comparator 410 as in the second embodiment. However, in the third embodiment, in the case of a black character / line drawing area, icode has been rewritten to 2, so that the selector 409 selects the triangular wave 501 when icode is 1 or 2.
, And when it is 0, the triangular wave 502 is selected.

As described above, according to the third embodiment, when an image in which images having different characteristics are mixed is output in hard copy by a color printer, the character / line drawing area and the continuous tone image area are further divided into black characters Since the line drawing area is accurately detected and the image processing and the resolution are selected according to the image type, a high-quality hard copy image can be obtained.

In each of the above-described embodiments, two types of printers, the ink jet type and the laser beam type, have been described, but other types can be similarly applied. Also, an example in which the image type is separated into two types, that is, a character / line drawing or a continuous tone image has been described, but the present invention is not limited to this, and a larger number of image types can be classified to obtain an image. Fine control of image processing and output resolution according to the type is naturally included in the scope of the invention.

[0083]

[Modification of Third Embodiment] FIG. 26 is a block diagram showing a modification of the third embodiment. This modification has the configuration shown in FIG.
Similar to the modification of the first embodiment, a function of selecting a compression mode and a non-compression mode is added. Therefore, the figure
The difference from FIG. 8 is the same as the modification of the first embodiment described with reference to FIG. 24, and thus the description thereof will be omitted.

[0084]

Fourth Embodiment An image processing apparatus according to the fourth embodiment of the present invention will be described in detail below 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. 12 is a schematic view of a full-color copying machine system according to the fourth embodiment of the present invention. 1101 is a host computer, 1102 is a controller, 1103 is an image forming apparatus having a reader unit and a printer unit. is there.

The image forming apparatus 1103 makes a color copy of the original image placed on the original table and also controls the controller 1102.
Then, the color image sent from the computer 1101 is output. Here, so-called Desk Top Publishing (DTP) application software runs on the host computer 1101 to create or edit various documents and figures. The host computer 1101 converts the created document or graphic into PDL data described in a page description language (PDL) such as Adobe's PostScript, and a connection cable.
Send to controller 1102 through 243. Controller 110
2 translates the PDL data sent from the host computer 1101 and rasterizes it into an image signal for each pixel. The rasterized image signal is sent by the image forming apparatus 1103 through the connection cable 242, and the image is output.

Here, the host computer 1101, the controller 1102, and the image forming apparatus 1103 are bidirectional with each other.
It is possible to perform data communication.

[Overview of Image Forming Apparatus] FIG. 13 shows an image forming apparatus.
It is a general-view figure of 1103.

When copying an original image as a copying machine An original 202 placed on the original table glass 201 is illuminated with light by an illumination 203. Light reflected from the original 202 is reflected by the mirrors 204, 2
After passing through 05 and 206, an image is formed on the CCD sensor 208 by the optical system 207. In addition, the motor 209 causes the mirror 204 and the illumination 203.
A first mirror unit 210 including a second mirror unit 211 including a mirror 205, 206 is mechanically driven at a speed V.
Is driven at a speed of 1/2 V to scan the entire surface of the original 202.

The image processing unit 212 processes the image information output from the CCD sensor 208 as an electric signal, temporarily holds it in a memory 1108 described later, and outputs it as a print signal. The print signal output from the image processing unit 212 is sent to a laser driver (not shown) to drive four semiconductor laser elements (not shown). One of the laser beams emitted by the four semiconductor laser elements is scanned by the polygon mirror 213 and passes through the mirrors 214, 215 and 216 to form a latent image on the photosensitive drum 217. Each of the other laser beams is also scanned by the polygon mirror 213, forms a latent image on the photosensitive drum 221 via the mirrors 218, 219, 220, forms a latent image on the photosensitive drum 225 via the mirrors 222, 223, 224, and mirrors 226, 227, 228.
Then, a latent image is formed on the photosensitive drum 229.

In this way, the latent images formed on the respective photosensitive drums are respectively the developing device 230 for supplying yellow (Y) toner and the 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 any 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 by the conveyor belt 238 at a constant speed V. Therefore, the four semiconductor lasers are synchronized in timing with this. The element is driven.

When outputting an image sent from the host computer 1101 The image output from the host computer 1101 is directly transferred to the image memory 1109 of the controller 102 through the interface cable 243, and then the operation of the copying machine is performed. An image is formed as in the case.

[Flow of Image Signal] FIG. 14 is a block diagram showing the flow of the image signal.

Image processing unit 212 The image information of the original 202 is converted by the CCD sensor 208 into image signals of three color components of red (R), green (G) and blue (B) representing the target image, Each is output as a digital signal.

An input masking unit 1112 converts the input R0G0B0 signal into a standard RGB color space signal by the calculation shown in the following equation. 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 1104 denotes a brightness / density conversion unit, which is a RAM or RO
It is composed of a lookup table of M and performs the operation shown in the following equation. C1 = -K ・ log (R / 255) M1 = -K ・ log (G / 255)… (7) Y1 = -K ・ log (B / 255) where K is a constant and the base of the logarithm is 10.

An output masking / UCR unit 1106 converts the M1C1Y1 signal into a YMCK signal which is the toner color of the image forming apparatus 1103 by the calculation shown in the following equation. However, aij (i = 1,
2,3,4 j = 1,2,3,4) is a device-specific constant in consideration of the tint characteristics of the toner. However, K = min (C1, M1, Y1)… (9)

From the above equations (6) to (9), 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 1105 denotes a character / line drawing detection unit, which judges whether or not each pixel in the document image is a part of a character or a line drawing, and generates a judgment signal TEXT. A compression / decompression unit 1107 compresses the C1Y1M1 image signal and the determination signal TEXT to reduce the amount of information, and then stores the data in the memory 1108 and decompresses the data read from the memory 1108 to obtain the C1Y1M1 image signal and the determination signal TEXT. To play.

Controller 1102 1110 is a CPU that controls the entire controller 1102 based on the program stored in the program ROM 1110a, and also performs conversion of PDL data using the RAM 1110b and buffer.

An image memory 1109 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 semiconductor laser described above. Is sent to a PWM circuit 1113, which will be described later, which forms a PWM signal for Also,
The image memory 1109 not only holds the above YMCK signal, but also the RGB signal output from the host computer 1101 and the RGB signal output from the input masking unit 1112 (in this case, the brightness / density conversion unit 1104 and the output masking unit). / UCR part 1
In 106, a parameter for outputting the input signal as it is (through) is set) and the like may be held.

Reference numeral 1111 is a character / line drawing detection unit, the details of which will be described later.

[Operation of Copying Machine] In the system of this embodiment, the operation of the copying machine alone (hereinafter referred to as "copying machine operation").
, And "system operation" including the controller 1102 exist, first, the operation of the copying machine will be described.

In the case of the operation of the copying machine, the image signal output from the CCD sensor 208 passes through the input masking section 1112 and the brightness / density conversion section 104, is compressed by the compression / expansion section 1107, and is then written in the memory 1108. In addition, the determination signal TEXT output from the character / line drawing determination unit 1105 is also stored in the compression / decompression unit 110.
After being compressed by 7, it is written to memory 1108. Then, the data read from the memory 1108 is stored in the compression / decompression unit 1.
The data is expanded by 107 and sent to the laser driver through a PWM circuit 1113 described later in synchronization with the image forming timing of the copying machine. FIG. 15 is a diagram showing writing / reading timing of image data in the operation of the copying machine.

In FIG. 15, the image signal is written in the memory 1108 at the timing indicated by reference numeral 1301, and the reference numerals 1302 to 1305.
It is read at the timing shown by. As shown in the figure, the timing relationships indicated by reference numerals 1302 to 1305 are, respectively, time d /
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 1302 is later than the write start timing indicated by reference numeral 1301.

[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.

Scan Operation This is an operation to take in the image signal obtained by reading the original document into the controller 1102. The image memory 1109 stores RGB data or YMCK.
Data is retained. When reading RGB data, as described above, the brightness / density converter 1104 and output masking / UC
It goes through with the R section 1106. In this way, RGB data and YMCK data can be captured on a common line.

PDL data conversion operation This is an operation for converting the PDL data input from the host computer 1101 into a full-color image and writing it in the image memory 1109. This full-color image is displayed in YMCK according to the output characteristics (density characteristics, color reproduction characteristics) of the image forming apparatus 1103.
It is developed as image data separated into four colors.

Character / Line Drawing Extracting Operation This is an operation for reading out the full-color image data expanded and written in the image memory 1109, and determining whether or not each portion of the full-color image is a character / line-drawing portion.
The character / line drawing detection unit 1111 indicates whether or not each part of the full-color image read from the image memory 1109 is a character / line drawing unit, and outputs a judgment signal TEXT indicating the judgment result to the image memory 1111.
09 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 1109 in synchronization with the rotation of the four photosensitive drums and sending them to the PWM circuit 1113 described later. .

Operation Timing FIG. 16 is a diagram showing the write / read timing of the image data in this system operation. The scan operation or the PDL data conversion operation is performed in the section indicated by reference numeral 1201, and at the same time, the write to the image memory 1109 is performed. The action is taken. The image data written in the image memory 1109 is subjected to character / line drawing extraction in the section indicated by reference numeral 1202, and at the same time, reference numerals 1203 to 1
It is read at the timing indicated by 206. 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 1111 generates a determination signal TEXT, an operation of recording the generated determination signal TEXT in the image memory 1109, full-color image data and its determination signal TEXT. Is read out at the same time (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 1110. That is, the CPU 1110 can realize the writing and reading operations with respect to the image memory 1109 by time division.

[Character / Line Drawing Detection Unit] FIG. 17 is a block diagram showing the configuration of the character / line drawing detection unit 1105.
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. 17, reference numeral 1601 denotes an ND signal generator, which generates an ND signal which is a lightness signal considering human visual sensitivity characteristics from a full-color RGB image signal by a product-sum operation shown in the following equation. Here, d1, d2, and d3 are constants in consideration of human luminosity characteristics.

Reference numeral 1602 denotes a character / line drawing determination unit which 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. 18 is a block diagram showing the configuration of the character / line drawing detection unit 1111.
A character and line drawing portion is extracted from the image signal, and when the pixel constitutes a character or line drawing portion, a determination signal TEXT which is '1' and is otherwise '0' is generated.

In FIG. 17, reference numeral 1701 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 1602 is the same as the character / line drawing determination unit 1602 shown in FIG.

[Judgment signal TEXT] FIG. 19 is a diagram for explaining the judgment signal TEXT. 1401 shows an example of a document to be read or an image to be printed out, and 1402 shows the judgment signal TEXT in the image 1401 two-dimensionally. Is the image shown in. That is, the character / line drawing portion in the image 1401 is indicated by “black” in the image 1402, and the other portions are indicated by “white”. 14
03 is an image obtained by enlarging a part of the image 1402, and the pixels indicated by reference numeral 1404 indicated by reference numeral 1404 are pixels constituting a character / line drawing portion,
The TEXT signal becomes '1'. On the other hand, ○ indicated by reference numeral 1405
The pixel of the mark is a pixel which configures other than the character / line drawing, and the TEXT signal becomes “0”.

[Image Memory] FIG. 20 is a diagram for explaining the structure of the data held in the image memory 1109 and the method of reading the data, and 1501 shows an address map in the image memory 1109. Yellow (Y) image data 1502, magenta (M)
Image data 1503, cyan (C) image data 1504, and black (K) image data 1505 each have 8-bit information per pixel. Also, the judgment signal TEXT data 1506
Has 1 bit of information per pixel.

Reference numeral 1507 conceptually shows how each of the above data is read. In other words, Y image data 150
2 is the M image data 150 in synchronization with the image formation on the photosensitive drum 217.
3 is the C image data 150 in synchronization with the image formation on the photosensitive drum 221.
4 is the K image data 150 in synchronization with the image formation on the photosensitive drum 225.
5 is read in synchronization with the image formation on the photosensitive drum 229. Further, the data 1506 of the determination signal TEXT is read out simultaneously in four systems (in parallel) in synchronization with all the four photosensitive drums.

[PWM Circuit] FIG. 21 is a block diagram showing the configuration of the PWM circuit 1113.

In FIG. 21, 1901 is a PWM for yellow (Y)
In the circuit, the yellow (Y) digital image signal 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 yellow (Y) semiconductor laser element is generated. 1902 is a magenta (M) PWM circuit, 1903 is a cyan (C) PWM circuit, 1904 is black (K)
Each of the PWM circuits for input receives the digital image signal of the color component and the determination signal TEXT in synchronization with it, and generates an analog signal to be sent to the laser driver that drives the semiconductor laser device.

FIG. 22 is a block diagram showing the configuration of the PWM circuit for each color component, which has the same circuit configuration regardless of the color components.

In FIG. 22, 2001 is a D / A converter,
The input digital image signal is converted into an analog image signal. Reference numeral 2002 denotes an image triangular wave generator that emphasizes gradation, and generates a triangular wave having a period of two pixels. Reference numeral 2003 denotes a triangular wave generating circuit for an image in which resolution is emphasized, and generates a triangular wave having one pixel cycle. A selector 2004 selects and outputs one of two triangular waves having different periods based on the determination signal TEXT. That is, the selector 2004 selects the number of PWM lines (resolution) based on the determination signal TEXT. A comparator 2005 compares the analog image signal output from the D / A converter 2001 with the triangular wave selected by the selector 2004.

With the above configuration, in the character and line drawing parts, the triangular wave of one pixel period which emphasizes the resolution is compared with the analog image signal, while in the parts other than the character and line drawing parts, the two pixel period which emphasizes the gradation property. 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 that 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. 23 is an example of a timing chart in the PWM circuit. The upper part of the figure shows the PWM timing in the case where the gradation is emphasized, and the output 1801 of the D / A converter 2001 and the triangular wave 1802 in units of two pixels are compared. Then, the pulse signal 1803 is output from the comparator 1105. On the other hand, the lower part of the figure shows the PWM timing when importance is placed on the resolution. The output 1804 of the D / A converter 2001 is compared with the triangular wave 1805 for each pixel, and the comparator 1105 outputs a pulse signal 1806.

[0131]

[Modification of Fourth Embodiment] FIG. 27 is a block diagram showing a modification of the fourth embodiment, in which the same functional portions as those in FIG. 14 are designated by the same reference numerals.

In FIG. 27, a compression / decompression unit 1109a has a function of compressing the above YMCK signal and then storing the YMCK signal in the image memory 1109, and the compression stored in the image memory 1109.
It has the function of extending the YMCK signal. That is, when the compression mode is set by the CPU 1110, the compressed YMCK signal is held in the image memory 1109. When the non-compression mode is set, the YMCK signal is held in the image memory 1109 as it is.

The compression / expansion algorithm used in the compression / expansion unit 1109a is arbitrary and is not particularly limited. For example, block encoding using orthogonal transformation such as the so-called JPEG method, DPCM encoding using a difference value for each pixel, or the like can be used. Further, in the present embodiment, an example in which the image data is compressed / decompressed by hardware has been shown, but it may be performed by software.

In the print-out operation of this embodiment, the compressed full-color image signal stored in the image memory 1109 is expanded by the compression / expansion unit 1109a, and then the character / line drawing detection unit 1111 or the PWM circuit 1113. Sent to. In addition, the uncompressed image data stored in the image memory 1109 remains unchanged, and the character / line image detection unit 1111 or the PWM circuit is used.
Sent to 1113.

Actually, each part of the image to be output is a character / line drawing part for which resolution is important, or a character / line drawing part for which gradation is important.
Since the pulse signals 1803 and 1806 are adaptively switched and output by the determination signal TEXT indicating whether the portion is other than the line drawing, preferable image formation is performed.

As described above, regardless of whether the image is 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.

Further, since the generation of the judgment signal of the character / line drawing portion, the operation of recording the generated judgment signal in the image memory, and the reading of the image data and the judgment 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 where the above operation is sequentially performed.

In the above description, the characteristic signal is stored in the image memory 1109 in the controller 1102, 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 a character / line drawing, but a black character / line drawing or
Features such as photographs and halftone dots may be used.

[0141]

[Other Embodiments] Even if the present invention is applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), an apparatus (for example, a copying machine) Machine, facsimile machine, etc.).

Another object of the present invention is to supply a storage medium having a program code of software for realizing the functions of the above-described embodiments to a system or apparatus, and to supply the computer (or CPU or M / M) of the system or apparatus.
Needless to say, this can also be achieved by the PU) reading and executing the program code stored in the storage medium. In this case, the program code itself read from the storage medium implements the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention. Examples of the storage medium for supplying the program code include a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM,
CD-R, magnetic tape, non-volatile memory card, ROM, etc. can be used.

Further, by executing the program code read by the computer, not only the functions of the above-described embodiment are realized, but also the OS (operating system) running on the computer based on the instruction of the program code. It is needless to say that this also includes a case where the above) performs a part or all of the actual processing and the processing realizes the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written in the memory provided in the function expansion card inserted in the computer or the function expansion unit connected to the computer, based on the instruction of the program code, It goes without saying that a case where the CPU included in the function expansion card or the function expansion unit performs some or all of the actual processing and the processing realizes the functions of the above-described embodiments is also included.

[0145]

As described above, according to the present invention,
It is possible to provide an image processing apparatus and method for outputting an image in which images having different characteristics such as characters and line drawings and continuous tone images are mixed, to high quality using a relatively small memory.

It is also 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 block diagram showing the configuration of an image processing system according to an embodiment of the invention.

FIG. 2 is a flowchart showing an example of image type determination processing,

FIG. 3 is a diagram showing an example of a 3 × 3 pixel area used for image type determination,

FIG. 4 is a diagram for explaining determination of an image type,

5A is a diagram showing a specific determination example of the image area shown in FIG. 4;

5B is a diagram showing a specific determination example of the image area shown in FIG. 4;

5C is a diagram showing a specific determination example of the image area shown in FIG. 4;

5D is a diagram showing a specific determination example of the image region shown in FIG. 4;

5E is a diagram showing a specific determination example of the image area shown in FIG. 4;

FIG. 6 is a block diagram showing a configuration example of an image processing system according to a second embodiment of the present invention,

FIG. 7 is a diagram for explaining a triangular wave generated by a triangular wave generator according to the second embodiment,

FIG. 8 is a block diagram showing a configuration example of an image processing system according to a third embodiment of the present invention,

FIG. 9 is a block diagram showing the configuration of a general image processing system,

FIG. 10 is a diagram showing a document example in which images of various characteristics are mixed;

FIG. 11 is a flowchart showing an example of image type determination processing according to the third embodiment,

FIG. 12 is a schematic view of a full-color copying machine system according to a fourth embodiment of the present invention;

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

FIG. 14 is a block diagram showing an example of the flow of an image signal,

FIG. 15 is a diagram showing an example of writing / reading timing of image data in a copying machine operation;

FIG. 16 is a diagram showing an example of writing / reading timing of image data in the system operation;

FIG. 17 is a block diagram showing a configuration example of the character / line drawing detection unit shown in FIG.

FIG. 18 is a block diagram showing a configuration example of the character / line drawing detection unit shown in FIG.

FIG. 19 is a diagram for explaining a determination signal TEXT,

20 is a diagram for explaining the structure of data stored in the image memory shown in FIG. 14 and how to read it;

FIG. 21 is a block diagram showing a configuration example of a PWM circuit,

FIG. 22 is a block diagram showing a configuration example of a PWM circuit for each color component,

FIG. 23 is a diagram showing an example of a timing chart in the PWM circuit,

FIG. 24 is a block diagram showing a configuration of a modified example of the first embodiment,

FIG. 25 is a block diagram showing a configuration of a modified example of the second embodiment,

FIG. 26 is a block diagram showing a configuration of a modified example of the third embodiment,

FIG. 27 is a block diagram showing a configuration of a modified example of the fourth embodiment.

Claims (15)

[Claims] 1. Expansion means for expanding input image information described in a page description language and storing the expanded image data of each pixel in a first storage means, and an image stored in the first storage means. The image data stored in the first storage means and the determination means for determining the characteristics of the image for each pixel with reference to the data and storing the determination code indicating the result of the determination in the second storage means. Reading means for reading the discrimination code corresponding to the image data for each pixel from the second storage means, and reading the image data read from the first storage means by the reading means with the reading means. Means for selectively performing different image processing according to the discrimination code read from the second storage means by means for compressing image data, and the first storage means for compressing the image data. The image processing apparatus characterized by storing image data. 2. The image processing apparatus according to claim 1, wherein the expansion means stores raster image data obtained by converting the input image information in the first storage means. 3. The image processing apparatus according to claim 2, wherein the discriminating means starts the discriminating processing when the raster image processing by the developing means is completed. 4. The image processing apparatus according to claim 1, wherein the determining unit determines whether the pixel of interest is included in a character and line drawing area or a continuous tone image area. . 5. The image processing apparatus according to claim 4, wherein the discriminating unit performs the discriminating process by referring to image data of an area formed by the target pixel and a plurality of pixels around the target pixel. 6. The discriminating means carries out a discriminating process from the number of image data having different values existing in an area consisting of the plurality of pixels and the maximum value of the difference between the value of the pixel of interest and the value of peripheral pixels. The image processing apparatus according to claim 5, wherein 7. The processing means selectively performs simple binarization processing and pseudo halftone processing.
The image processing device described in. 8. The processing means performs the simple binarization process when the discrimination code indicates a character or a line drawing, and performs the pseudo halftone process when the discrimination code indicates a continuous tone image. The image processing device according to claim 7, wherein 9. The apparatus according to claim 1, further comprising a forming unit that forms a visible image on a recording medium based on the image data processed by the processing unit.
An image processing device according to any one of the above. 10. A first storage unit 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 first storage unit and the characteristics of each pixel are determined. Feature detecting means for generating a characteristic signal to be stored and storing it in the second storing means, and output means for reading out the image signal and its characteristic signal from the first and second storing means and outputting as a recording signal. And a compression means for compressing image data, wherein the first storage means stores the compressed image data,
The operation of generating the characteristic signal, the operation of storing the characteristic signal in the second storage means, and the operation of reading the image signal and the characteristic signal from the first and second storage means are substantially parallel to each other. An image processing apparatus characterized by being carried out. 11. A first 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 first storage means and the characteristics of each pixel are determined. Feature detecting means for generating a characteristic signal to be stored and storing it in the second storing means, and output means for reading out the image signal and its characteristic signal from the first and second storing means and outputting as a recording signal. And a compression unit for compressing image data, wherein the first storage unit stores the compressed image data. 12. The image according to claim 10 or 11, further comprising forming means for forming a visible image on a recording medium based on the recording signal output by the output means. Processing equipment. 13. An expansion step of expanding input image information described in a page description language and storing the expanded image data of each pixel in a first storage means, and an image stored in the first storage means. A determination step of determining the characteristics of the image for each pixel by referring to the data and storing a determination code indicating the determination result in the second storage means; and the image data stored in the first storage means. A reading step of reading the discrimination code corresponding to the image data of each pixel from the second storage means, and a step of reading the image data read from the first storage means in the reading step. And a processing step of selectively performing different image processing according to the discrimination code read from the second storage means, and a compression step of compressing image data, Image processing method characterized by storing image data compressed in the storage means. 14. A storage step of storing an input image signal in a first storage means; when the image signal is input from an external device, the image signal is read out from the first storage means, and each pixel thereof is read. A characteristic detecting step of generating a characteristic signal representing the characteristic of the image signal and storing the characteristic signal in the second storage means, and reading out the image signal and the characteristic signal from the first and second storage means and outputting it as a recording signal. And a compression step of compressing the image data, storing the compressed image data in the first storage means, generating the characteristic signal, and transmitting the characteristic signal to the second storage means. An image processing method characterized in that an operation of storing and an operation of reading the image signal and its characteristic signal from the first and second storage means are performed substantially in parallel. 15. A storage step of storing an input image signal in a first storage means; when the image signal is input from an external device, the image signal is read out from the first storage means, and each pixel thereof is read. A characteristic detecting step of generating a characteristic signal representing the characteristic of the image signal and storing the characteristic signal in the second storage means, and reading out the image signal and the characteristic signal from the first and second storage means and outputting it as a recording signal. And a compression step of compressing the image data, wherein the compressed image data is stored in the first storage means.