JPH1032690A - Image processor and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image processor surely executing a desired copy job though a memory becomes full by controlling housing so as to effectively utilize at least two holding means at the time of forming an image by at least two colors after temporarily reading an original image in a memory. SOLUTION: The image server part of this image processor receives an image signal sent from an image reading part to send to a housing control part 303 through a chrominance conversion part 301, a two color separation part 307 and a binarization part 302. At the time of a 'output mode after finishing reading', image data is compressed by a compressing/expanding part 307 and sent to an image storing part 304. First and second hard disks 403 and 404 within the part 304 store image data and when the hard disk quantity of one of them amounts to a limit, image data to store in the disk is stored in the null area of the other disk with a spare capacity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image processing apparatus and method, and more particularly to an image processing apparatus and method for forming an image after temporarily holding a plurality of document images.

[0002]

2. Description of the Related Art Conventionally, an image processing apparatus having a copying function has a sorter provided with a plurality of bins for discharging copied recording media, and can copy a plurality of originals in a plurality of copies. Was.

Further, a so-called electronic sort function for reading all original images to be copied, temporarily storing the image data in a memory such as a hard disk, and repeatedly reading out and printing out arbitrary image data from the memory is provided. 2. Description of the Related Art A digital copier provided with a digital camera is known. In such a copying machine, it is possible to discharge copied recording media in a sorted (classified) state without providing a sorter having a plurality of pins.

[0004]

However, in the above-mentioned conventional digital copying machine having an electronic sorting function,
There is a limit to the storage capacity of a memory for storing image data. Therefore, the number of documents that can be stored is also limited in advance.

For example, when the storage capacity of the memory is 100 sheets of A4 size documents and the bundle of documents to be copied is 102 sheets of A4 size, 100 sheets of documents can be stored in the memory, but the remaining 2 sheets are stored. Minutes of the original cannot be stored.

In such a state, in the above-described conventional copying machine, the copy job is canceled, an electronic sort operation is performed only on the document stored in the memory, or the sort mode is canceled. Group mode to copy the required number of copies for each original,
For example, processing such as copying the required number of copies of 100 originals is performed.

As described above, in the conventional copying machine, when it is desired to copy a plurality of copies of a plurality of documents and sort and output the copies, or when the documents to be copied cannot be stored in the memory, a copy job in an intended sort mode is executed. Could not do.

Further, when it is desired to place a plurality of document images on one recording medium, such as in a reduced layout mode or a pamphlet mode, it is necessary to read all the target documents and store them in a memory. In such a case, unless all target documents can be stored in the memory, normal output cannot be performed, so that the copy job has to be canceled.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and when a document image is once read into a memory and then formed / output, the intended copy job is reliably executed even when the memory is full. It is an object of the present invention to provide a possible image processing apparatus and method.

[0010]

As one means for achieving the above object, the image processing apparatus of the present invention has the following arrangement.

That is, input means for inputting an image signal, storage control means for storing the image signal in at least two holding means, and image forming means for forming an image based on the image signal stored in the holding means Wherein the storage control means stores the image signal in another holding means when the holding of the image signal in any of the holding means reaches the maximum.

Further, as a method for achieving the above object, the image processing method of the present invention includes the following steps.

That is, an image processing method for inputting an image signal, storing the image signal in at least two holding units, and forming an image based on the image signal stored in the holding unit. In any of the above, when the holding of the image signal reaches the maximum, the image signal is stored in another holding unit.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below in detail with reference to the drawings.

First Embodiment Configuration of Image Processing Apparatus FIG. 1 is a cross-sectional view showing an example of an image processing apparatus for forming a two-color image of red and black in the present embodiment. In FIG. 1, reference numeral 100 denotes an image processing apparatus main body; and 180, a circulating automatic document feeder (hereinafter referred to as "RD
F "). When a plurality of documents are stacked on the RDF 180 in an upward direction, the documents are sequentially read from the lowest document.

In the image processing apparatus 100, reference numeral 101 denotes a document table glass as a document table, 102 denotes a scanner including a document illumination lamp 103, a scanning mirror 104, and the like. Scanning mirrors 104 to 10 scan reflected light of the original document by reciprocating scanning.
6 through the lens 108 and the CCD sensor 109
Image.

Reference numeral 120 denotes an exposure control unit composed of a laser, a polygon scanner, or the like, and reference numeral 125 denotes an image server.
The image signal converted into the electric signal by the image sensor unit 109 is subjected to predetermined image processing described later in the image server unit 125. Then, the exposure control unit 120 irradiates the photosensitive drum 110 with laser beams 128 and 129 modulated based on an image signal from the image server.

Around the photosensitive drum 110, a primary charger 112, a black developing device 121, a red developing device 122, a transfer charger 118, a cleaning device 116, and a pre-exposure lamp 114
Is equipped. An image forming unit 126 is configured by the photosensitive drum 110 and the like.

In the image forming section 126, the photosensitive drum 110 is rotated by a motor (not shown) in the direction of the arrow shown in the figure, and after being charged to a desired potential by the primary charger 112, an image to be formed is formed. A laser beam 129 from the exposure control unit 120 corresponding to the black component is irradiated to form an electrostatic latent image. The electrostatic latent image formed on the photosensitive drum 110 is developed by the black developing device 121 and is visualized as a toner image. Next, a laser beam 128 corresponding to the red component of the image formed on the photoconductor drum 110 is irradiated to form an electrostatic latent image, which is visualized by the red developing device 122.

On the other hand, the transfer paper fed from the upper cassette 131 or the lower cassette 132 by the pickup rollers 133 and 134 is sent to the main body by the feed rollers 135 and 136, and is fed to the transfer belt 130 by the registration rollers 137. The visualized black toner image and red toner image are transferred to transfer paper by the transfer charger 118. After the transfer, the photosensitive drum 110 is placed in the cleaner device 1.
16 removes residual toner, and the pre-exposure lamp 114
As a result, residual charges are erased.

After the transfer, the transfer paper is separated from the transfer belt 130, and the toner image is recharged by pre-fixing chargers 139 and 140, which will be described later. And the discharge roller 142
The output tray 190 outside the image processing apparatus main body 100
Is discharged.

Reference numeral 138 denotes an attraction charger for attracting the transfer paper sent from the registration roller 137 to the transfer belt 130. Reference numeral 139 is used to rotate the transfer belt 130 and simultaneously forms a pair with the attraction charger 138 to form a transfer belt. 130
Is a transfer belt roller for adsorbing and charging the transfer paper.

Reference numeral 143 denotes a static eliminator for facilitating separation of the transfer paper from the transfer belt 130. Reference numeral 144 denotes a peeling charger for preventing image disturbance due to peeling discharge when the transfer paper is separated from the transfer belt 130. 139,140
Reference numeral 145 denotes a pre-fixing charger for compensating for the toner adsorbing force of the separated transfer paper and preventing image disturbance, and 145 and 146 de-electrify the transfer belt 130 and electrostatically initialize the transfer belt 130. A transfer belt static eliminator 147 is a belt cleaner for removing dirt from the transfer belt 130.

A paper sensor 148 detects the leading end of the transfer member fed onto the transfer belt 130, and is used as a synchronization signal in the paper feed direction (sub-scan direction).

The main body 100 is equipped with a deck 150 capable of storing, for example, 4000 transfer papers. The lifter 151 of the deck 150 rises according to the amount of transfer paper so that the transfer paper always contacts the paper feed roller 152. Also, a multi-bypass tray 153 capable of storing 100 transfer papers.
Is equipped.

Reference numeral 154 denotes a paper discharge flapper, which provides a path for double-sided recording (double-sided copying) or multiple recording (multiple copying) and discharge to the paper discharge tray 190 of the transfer paper sent from the discharge roller 142. Switch. Also, 1
55 is a reversing path for reversing the transfer paper, 158 is a lower transport path, and the transfer paper sent out from the discharge roller 142 is turned upside down via a reverse path 155 and is sent to the re-feed tray 156 via the lower transport path 158. Be guided.

Reference numeral 157 denotes a multiplex flapper for switching the path between the double-sided recording and the multiplex recording. The flapper is tilted leftward in the drawing to directly lead the transfer sheet to the lower transport path 158 without passing through the reversing path 155. Reference numeral 159 denotes a paper feed roller for feeding the transfer paper to the photosensitive drum 110 through the path 160. A discharge roller 161 is disposed near the discharge flapper 154, and is switched to the discharge side by the discharge flapper 154 to transfer the transfer sheet outside the apparatus (discharge tray 190).
To be discharged.

At the time of double-sided recording, the discharge flapper 154 is raised upward, and the multiple flapper 157 is tilted rightward in FIG.
And stored in the re-feed tray 156 upside down. Further, at the time of multiplex recording, the discharge flapper 154 is raised upward and the multiplex flapper 157 is tilted leftward in the drawing, so that the copied transfer paper is stored in the re-feed tray 156 via the transport path 158. Then, the transfer sheet stored in the re-feed tray 156 for both the duplex recording and the multiplex recording is
The sheet is guided to a registration roller 137 of the main body via a path 160 by a sheet feeding roller 159 one by one from below.

On the other hand, in order to discharge the transfer paper as it is, the discharge flapper 154 may be lowered. Further, in order to discharge the transfer sheet in reverse, the discharge flapper 154 is raised upward, the multiple flapper 157 is tilted rightward in the figure, and the copied transfer sheet is conveyed to the conveyance path 155. After the end passes the first feed roller 162, the reversing roller 1
By 63, the sheet is conveyed to the second feed roller 164 side. Then, the inverted transfer paper is discharged to the discharge tray 190 by the discharge roller 161.

Reference numeral 300 denotes an operation unit which includes a display panel such as an LCD, various switches, and the like, and inputs instructions from an operator, and notifies the operation status of the apparatus.

In the image processing apparatus 100 of the present embodiment, the two-color image formation of red and black is executed by the configuration described above.

FIG. 2 shows an outline of a functional configuration of the above-described image processing apparatus. 2, an image reading unit 201 includes the CCD sensor 109, the analog signal processing unit 202, and the like. Original image 200 input via lens 108
Is formed on the CCD sensor 109 and is converted into an analog electric signal. In the present embodiment, a plurality of document images 200 are input by the RDF 180. The converted image signal is input to the analog signal processing unit 202, where the sample &
After performing hold, dark level correction, and the like, analog / digital conversion (A / D conversion) is performed. Then, the digitized image signal is subjected to shading correction (variation of a sensor for reading a document and correction of light distribution characteristics of a document illuminating lamp) and predetermined scaling processing, and then input to the image server unit 125. Is done.

In the image server unit 125, the image signal is subjected to necessary correction processing in an output system such as γ correction, smoothing processing, edge enhancement, and other image processing and processing, and output to the printer unit 204. You.

The printer unit 204 includes an exposure control unit 120 made of a laser or the like and an image forming unit 1 shown in the sectional view of FIG.
26, which comprises a transfer paper transport control unit and the like, and forms and outputs a visible image on the transfer paper based on the input image signal.

The image reading unit 201, the image server unit 125, and the printer unit 204 include a CPU control unit 20.
5 controls the sequence and the like as a whole. C
The PU control unit 205 includes a CPU 206, a ROM 207, an R
AM 208 and the like.
The control is executed by executing the control program held in 07 using the RAM 208 as a work area.

Next, the image server 125, which is a feature of the present embodiment, will be described in detail. FIG. 3 shows the image server unit 12.
5 is a block diagram showing a detailed configuration of No. 5. FIG.

The image signal sent from the image reading unit 201 is input as luminance data of each of red (R), green (G), and blue (B), and is input to the color conversion unit 3.
01 is sent. The color conversion unit 301 stores an LUT for converting the input luminance data into density data, and outputs a table value (density data) corresponding to the input luminance data, so that each of the RGB colors is output. The luminance data is converted into corresponding cyan (C), magenta (M), and yellow (Y) density data. C
The image signal converted to the MY density data is output from the two-color separation unit 3.
08, and based on the density data, multi-valued image data indicating density values of image forming colors, that is, black (BK) and red (R), which are toner colors in the printer unit 204, is generated.

After that, the multi-value density data of each color is sent to the binarization unit 302 and binarized, and the density value is converted to “0” or “255”. Is converted into 1-bit image data of “0” or “1”. This binarization reduces the overall image data amount.

However, in general, when binarization of image data is performed (8 bits → 1 bit), the number of gradations is 256.
Since the number of gradations is reduced from two gradations to two gradations, for example, image data including many halftones such as a photographic image has a remarkable deterioration in image quality.
Therefore, it is necessary to perform pseudo halftone expression using binary data. In the present embodiment, an error diffusion method is used as a method for pseudo-halftone expression using binary data.
According to this method, when the density of a certain pixel is larger than a fixed threshold, the density data is determined to be "255", and when the density is equal to or less than the fixed threshold, the density data is determined to be "0". Then, the difference between the actual density data and the binarized data is distributed to neighboring pixels as an error signal. Note that the distribution of the error is performed by multiplying the error generated by the binarization by a matrix-shaped weight coefficient prepared in advance and adding the multiplied error to neighboring pixels. As described above, by applying the error diffusion method in the present embodiment, the density average value of the entire image is preserved, and the halftone can be expressed in a pseudo binary manner.

The binarized image data corresponding to each color is sent to the storage control unit 303, and according to the layout mode specified by the operation unit 300, either mode of simultaneous output or output after reading is selected. Is performed. still,
The former “simultaneous output mode” is a mode in which image data is stored in the image storage unit 304 via the compression / decompression unit 307, and at the same time, the output of the image is performed in parallel. Is a mode in which all the read images are stored in the image storage unit 304 via the compression / decompression unit 307, and then output again.

After the mode selection as described above is performed, the image data is compressed by the compression / decompression unit 307 and stored in the image storage unit 304.

The image storage unit 304 includes a SCSI controller 405, first and second buffer memories 401 and 402 for storing black and red image signals, and first and second hard disks 403 for storing black and red image signals. 40
In accordance with a command from the SCSI controller 405, the image data whose speed has been converted in each of the buffer memories 401 and 402 is written to each of the hard disks 403 and 404.

The first and second hard disks 40
For example, the capacity of the first hard disk 403 for storing the black component may be larger than that of the second hard disk 404 if the image to be processed has most of the black component. It may be a capacity. However, since the data actually stored is compressed data,
Even if the same number of pixels is processed, the used amount of each hard disk differs.

In the present embodiment, the storage control unit 303 manages the usage status of each of the first and second hard disks 403 and 404, and when one of the hard disk capacities reaches a limit, the limit is reached. The compressed data of the color to be stored in the hard disk is stored in a free area of the other hard disk having a sufficient capacity. That is, it is possible to use the hard disk provided in the image storage unit 304 to the maximum extent and store and hold the maximum number of image data.

When the "simultaneous output mode" is selected, the image data is output to the subsequent processing units without waiting for the image data to be stored in the image storage unit 304.

As described above, the plurality of image data stored in the image storage unit 304 under the control of the storage control unit 303 are expanded and output in the order according to the mode specified by the operation unit (not shown). You. For example, when the “output mode after reading is completed” is selected and the “electronic sort” mode is further selected, reading of image data from each of the hard disks 403 and 404 in the image storage unit 304 is performed from a plurality of sheets. By controlling the order in which some original images are output one by one, a so-called “sorter” function can be performed on the data.

The image data read from the image storage unit 304 and the image data not stored in the image storage unit 304 are sent to the smoothing unit 305. In the smoothing unit 305,
First, the 1-bit binary image data is converted into 8-bit multi-value data, so that the value of the image data is set to “0” or “255”. Then, the converted image data is replaced with a weighted average value obtained by summing up a product obtained by multiplying a predetermined matrix-like coefficient by a density value of a neighboring pixel. This gives 2
Since the value image data is converted into multi-value data according to the density value of the neighboring pixel, it is possible to reproduce an image quality closer to the read document image.

Next, the smoothed image data is input to the gamma correction unit 307. When outputting black and red density data to the printer unit 204, the γ correction unit 307 converts the density data using an LUT in consideration of the density characteristics of the printer unit 204. The output is adjusted according to the set density value.

As described above, the image server unit 12
From 5, 8-bit black and red image data are output to the printer unit 204, and image formation using the two colors is performed.

As described above, according to this embodiment, in an image processing apparatus that stores a plurality of image data in a memory in the apparatus and reads out the plurality of image data to form a two-color image, Even if the memory for storing color image data becomes full, it is possible to efficiently use the memory and store and hold the maximum number of image data by using the memory for other colors to store the data. Become.

<Second Embodiment> Hereinafter, a second embodiment according to the present invention will be described.
An embodiment will be described.

In the first embodiment, red-black 2
Although the image processing apparatus that performs image formation using colors has been described, the present invention is not limited to two-color image formation. In the second embodiment, an example in which the present invention is applied to an image processing apparatus capable of forming a full-color image will be described.

The configuration of the image processing apparatus according to the second embodiment is the same as the configuration of FIG. 1 shown in the first embodiment described above, except that yellow (Y), magenta (M), cyan (C), and black (K) are used. Developing devices for each of the four colors are provided. The other configuration is the same, and the description is omitted. In addition, since the functional configuration is the same as that of FIG. 2, each configuration will be referred to by the same reference numeral as in the first embodiment.

Next, the image server 125 according to the second embodiment will be described in detail. FIG. 4 is a block diagram illustrating a detailed configuration of the image server unit 125 according to the second embodiment. In FIG. 4, the same functions as those in FIG. 3 of the first embodiment are denoted by the same reference numerals as in FIG.

The image signal sent from the image reading unit 201 is sent to the color conversion unit 301 as luminance data of each of red (R), green (G), and blue (B). The color conversion unit 301 stores an LUT for converting the input luminance data into density data, and outputs a table value (density data) corresponding to the input luminance data, so that each of the RGB colors is output. The luminance data corresponds to cyan (C), magenta (M),
The density data is converted into yellow (Y) and black (K) density data.

Thereafter, the CMYK multi-value density data is sent to the binarization unit 302 and binarized, and the image data amount as a whole decreases. Here, the pseudo halftone processing by the error diffusion method is performed simultaneously.

The binarized image data corresponding to each color is sent to the storage control unit 303, and according to the layout mode designated by the operation unit 300, either one of the simultaneous output mode or the output mode after completion of reading is selected. Is performed.

After the mode is selected, the image data is compressed by the compression / decompression unit 307, and the image data is stored in the image storage unit 30.
4 is stored. The image storage unit 304 includes a SCSI controller 509, and first to fourth buffer memories 501 to 50 that hold Y, M, C, and K color image signals, respectively.
4, first to fourth hard disks 505 to 508 for respectively storing color image signals of Y, M, C, and K;
In accordance with a command from the CSI controller 509, the image data whose speed has been converted in each of the buffer memories 501 to 504 is written to each of the hard disks 505 to 508.

In the second embodiment, the storage control unit 303 manages the usage status of each of the first to fourth hard disks 505 to 508, and when any of the hard disk capacities reaches a limit, the limit is reached. The compressed data of the color to be stored in the hard disk is stored in a free space of another hard disk having a sufficient capacity. That is, it is possible to use the hard disk provided in the image storage unit 304 to the maximum extent and store and hold the maximum number of image data.

As described above, a plurality of image data stored in the image storage unit 304 under the control of the storage control unit 303 are expanded and output in an order according to a mode designated by an operation unit (not shown). You. For example, when the “output mode after reading is completed” is selected and the “electronic sort” mode is further selected, reading of image data from each of the hard disks 505 to 508 in the image storage unit 304 is performed from a plurality of sheets. By controlling the order in which some original images are output one by one, a so-called “sorter” function can be performed on the data.

The image data read from the image storage unit 304 and the image data not stored in the image storage unit 304 are sent to the smoothing unit 305. In the smoothing unit 305,
The 1-bit binary image data is converted into 8-bit multi-value data and smoothed. Then, the smoothed image data is input to the γ correction unit 307, and an LUT for each color density data in consideration of the density characteristics in the printer unit 204.
, And further adjusts the output according to the density value set by the operation unit 300. In this way, 8-bit YMCK image data is output from the image server unit 125 to the printer unit 204, and full-color image formation is performed.

As described above, according to the second embodiment,
In an image processing apparatus that stores a plurality of image data in a memory in the apparatus and reads out the plurality of image data to form a full-color image, even if a memory to store image data of a certain color becomes full, By using a color memory for storage, it is possible to efficiently use the memory and store and hold the maximum number of image data.

In the second embodiment, an example has been described in which the present invention is applied to an image processing apparatus capable of forming a full-color image in four colors. However, an image processing apparatus in which an image is formed in at least two colors such as three colors. If so, it is of course applicable.

In each of the above-described embodiments, the image data is stored in the image storage unit for each color component (black / red, Y /
M / C / K, etc.).
The present invention is not limited to this example. For example, the present invention is applicable to a configuration in which a memory area is divided into two or more, such as a luminance component and a color difference component, and image data is held.

<Other Embodiments> Even if the present invention is applied to a system constituted by a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), an apparatus comprising one device (for example, For example, the present invention may be applied to a copying machine, a facsimile machine, and the like.

Further, an object of the present invention is to supply a storage medium storing a program code of software for realizing the functions of the above-described embodiments to a system or an apparatus, and to provide a computer (or CPU) of the system or the apparatus.
And MPU) read and execute the program code stored in the storage medium.

In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.

As a storage medium for supplying the program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD
-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

When the computer executes the readout program code, 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. ) May perform some or all of the actual processing, and the processing may realize the functions of the above-described embodiments.

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

[0071]

According to the present invention as described above,
In an image processing apparatus that once reads an original image into a memory and forms an image in at least two colors, the memory provided for each color can be used effectively, and the maximum number of original images can be held. The maximum possible image forming operation can be performed.

[0072]

[Brief description of the drawings]

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

FIG. 2 is a block diagram illustrating a functional configuration of the image processing apparatus according to the embodiment.

FIG. 3 is a block diagram illustrating a detailed configuration of an image server unit according to the embodiment.

FIG. 4 is a block diagram illustrating a detailed configuration of an image server unit according to a second embodiment of the present invention.

[Explanation of symbols]

 302 Binarization unit 303 Storage control unit 304 Image storage unit 307 Compression / expansion unit 401, 402, 501 to 504 Buffer memory 403, 404, 505 to 508 Hard disk 405, 509 SCSI controller

Claims (11)

[Claims] An input unit for inputting an image signal; a storage control unit for storing the image signal in at least two holding units; and an image forming unit for forming an image based on the image signal stored in the holding unit. The image processing apparatus according to claim 1, wherein the storage control unit stores the image signal in another holding unit when the holding of the image signal in any of the holding units reaches a maximum. 2. The image according to claim 1, further comprising compression means for compressing the image signal, wherein said storage means stores the image signal compressed by said compression means in said holding means. Processing equipment. 3. The storage control unit according to claim 2, wherein when one of the storage units holds the image signal to the maximum, the storage control unit stores the image signal in a free area of another storage unit. Item 3. The image processing device according to Item 2. 4. The image processing apparatus according to claim 3, wherein said storage control means stores the image signal components in each holding means. 5. The image processing apparatus according to claim 4, wherein the storage control unit stores the image signal in each holding unit for each color component of the image signal. 6. The image processing apparatus according to claim 5, wherein said image signal has two color components, and said holding means is two, each of which holds an image signal for each color component. . 7. The image processing apparatus according to claim 5, wherein said image signal has four color components, and said holding means is four, each of which holds an image signal for each color component. . 8. The image forming apparatus according to claim 1, wherein said input means inputs image signals corresponding to a plurality of document images, said storage control means stores image signals corresponding to said plurality of document images in said holding means, 2. The image processing apparatus according to claim 1, wherein the means forms an image based on image signals corresponding to the plurality of document images. 9. An image processing apparatus according to claim 1, wherein said image forming means forms an image on a recording medium. 10. An image processing method for inputting an image signal, storing the image signal in at least two holding units, and forming an image based on the image signal stored in the holding unit, the image processing method comprising: The image signal is stored in another holding means when the holding of the image signal reaches the maximum in any one of the above. 11. A computer readable memory in which a program code for image processing is stored, wherein a code for an inputting step of inputting an image signal and said image signal are stored in at least two holding means, In the case where the holding of the image signal reaches the maximum, the code of the storage control step of controlling the image signal to be stored in another holding unit, and an image based on the image signal stored in the holding unit And a code for an image forming step to be formed.