JPH05199383A - Image forming device - Google Patents

Abstract

PURPOSE:To obtain the image forming device in which a high quality continuous gradation picture is recorded with a small capacity picture memory. CONSTITUTION:Information used to distinguish whether data are binary data or multi-value data for each picture element is stored in a picture discrimination memory 14 and data in mixture of binary data and multi-value data are stored in a picture memory 13. A picture data signal 22 from the picture data memory 13 is given to a demultiplexer 23, in which the signal is demultiplexed into binary data and multi-value data based on a picture discrimination signal 21 from the picture discrimination memory 14, the binary picture data are processed by a binary data picture expansion section and the multi-value data are processed by a multi-value picture expansion section 25, they are multiplexed by a multiplexer 26 and the synthesized signal is sent to a gradation processing section 16 as a picture expansion signal 27. In this case, the multi-value picture expansion section 25 uses also information of adjacent picture element data to apply interpolation processing to the data and the data are converted into a continuous gradation level.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus having an image memory and capable of recording a halftone image.

[0002]

2. Description of the Related Art Conventionally, printers of various principles have been proposed as output terminals for personal computers, workstations, etc., but in recent years, especially black and white laser beam printers (hereinafter referred to as LBP) using an electrophotographic process and laser exposure technology. ) Is highly advantageous in terms of recording speed and print quality, and is rapidly becoming popular.

On the other hand, in the market, there is an increasing demand for full color LBP, but in the case of full color LBP, not only the binary image data handled by the black and white LBP but also the image data of halftone of color is targeted for output. Therefore, it is necessary to perform image processing capable of handling both binary image data and halftone image data.

Generally, in the case of an image output device to which an electrophotographic process such as LBP is applied, there are problems in the stability of the electrophotographic process itself, and therefore black or white two-gradation output is often used. In the conventional two-tone printer, binarization by the dither method is often used in the halftone image portion.

The principle of the dither method will be described below with reference to FIG. The halftone image portion divides the input image (1) into N × M blocks and compares the pixel level in each block of the input image with the N × M threshold matrix (2) for each pixel (white = pixel level > Threshold value, black = pixel level ≦ threshold value, and binarization is performed according to the magnitude relationship. By repeating this for each matrix size, a dither image (3) is obtained. As the threshold matrix (2), there are a dot concentrated type in which dots are concentrated to make gradation smooth, and a dot dispersed type in which dots are dispersed to prioritize resolution.

FIG. 15 shows a circuit structure of the binary dither method. This is to sequentially move the multivalued pixels of the input image signal (A), and to correspond to this, the threshold matrix memory (Mx) row and the row. The columns are addressed, the respective threshold values are sequentially read, and the magnitude of the input image signal (A) is compared with the comparison circuit (B) to obtain a binarized output image signal (C). This binarized output image signal is used as a recorded image by the printer engine.
It is sent to (not shown) and printed. The printed image of the binary dither method has a drawback that the dither pattern is conspicuous and the resolution of the halftone portion is low.

Recently, in order to improve the quality of a printed image, a printer engine capable of multi-value recording of three or more values has been developed. However, in order to print a recording density of 300 DPI, that is, four full colors of 256 gradations with a resolution of A4 paper size, an image memory of 30 megabytes or more is required, which causes a problem of increasing the cost and size of the printer. there were.

[0008]

As described above, a low-priced monochrome LPB (binary printer) has low image quality, and a full-color LPB (multi-gradation printer) capable of recording full color requires a large-capacity image memory. Therefore, there was a problem that the price would be high.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and to provide a low cost image forming apparatus which has a small capacity image memory and is capable of high-quality continuous tone recording.

[0010]

According to the present invention, a halftone image is stored in an image data memory as medium resolution multi-valued image data and a binary image is stored as high resolution binary image data in an image data memory, respectively, and the two image types are stored. Image discrimination information storage means for distinguishing between
Image conversion means having a function of converting the multi-valued image data and the binary image data into recorded image data of a predetermined format in accordance with the information from the image discrimination information storage means and interpolating the multi-valued image data. And image recording means for forming a recorded image using the recorded image data.

[0011]

According to the present invention, in order to efficiently use the image data memory according to the type of image, the image data memory has a small capacity, and the resolution of all types of image data is unified by interpolation processing. It is possible to obtain a high quality mixed recording image.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to FIGS.
This will be explained with reference to 13.

FIG. 1 shows a schematic configuration of the image forming apparatus in this embodiment. The image forming apparatus 1 develops a printer code 5 sent from a host computer 4 as image data and outputs an image recording signal. 6 and an image processing unit 2 and a printer engine 3 that forms a recorded image 7 from an image recording signal 6.

In this embodiment, the printer code 5 from the host computer 4 is taken as an example of the image information source, but the image information source may be an image file or a video image signal.

There are various types of printer codes 5 depending on the printer, such as printer control language and page description language.

The printer engine 3 is a color image photographic method of laser exposure and has a gradation of 256 per pixel for each color with a recording density of 300 DPI.

FIG. 2 is a schematic diagram of the configuration of the image processing unit 2 shown in FIG. 1. The communication interface 11 communicates with the host computer 4 and receives the printer code 5. The image development unit 12 interprets the printer code 5 and writes the developed image information in the image data memory 13 and the image discrimination memory 14. The image decompression unit 15 converts the information in the image data memory 13 and the image discrimination memory 14 into the resolution and the number of gradations of the printer engine 3 and improves the image quality of the binary image data and interpolates various images according to the present invention. Perform processing. In the gradation processing unit 16, image density adjustment, gamma correction,
In addition to processing such as screen angle, processing for stabilizing the gradation of the printer engine 3 is performed. The engine interface 17 uses the image recording signal 6 output from the gradation processing unit 16.
Is sent to the printer engine 3.

The image developing unit 12 shown in FIG. 2 will be described in detail. FIG. 3 shows a flow chart of the processing of the image developing unit 12, and FIG.
FIG. 4 shows a state of writing in the image discrimination memory 14 and FIG.
FIG. 4A shows writing of binary 8-color data into the memory, and FIG. 4B shows writing of halftone data into the memory. The processing of the image expansion unit 12 is executed by software,
When interpreting the printer code 5 and expanding it in the image data memory 13, the following procedure of FIG. 3 is performed.

(1) It is determined whether the received printer code (S1) is a code relating to image development (S4). If the code is not related to image development, the processing operation of the predetermined code is performed as in the conventional printer (S8).

(2) If the received printer code is a code related to image development, binary 8-color data (W
(White), Bk (black), R (red), G (green), B (blue), Y (yellow), M (magenta), C (cyan))
(S5).

(3) If the printer code is binary 8-color data, as shown in FIG. 4A, the printer engine 3
The image data is expanded with 300DPI, which is the resolution of
6), Write in each color memory of the image data memory 13.
Write 0 to the bit of the image discrimination memory 14 of the pixel corresponding to the address of the written pixel.

(4) If the code is not the binary 8-color data but the intermediate color data (NO in S5), the code data is Y,
Converted to 8-bit data of 256 gradations for each color of M, C, Bk,
Furthermore, it is compressed to 16-level 4-bit data by the 16-value dither method, which is half the resolution of the printer engine 3.
Expanded to halftone image data by 0DPI, 16-value dither method (S
7), Write in each color memory of the image data memory 13.
0 is written in the bit of the image discrimination memory 14 of the pixel corresponding to the address of the written pixel. For example, when the level is 5, 0101 is written in binary as shown in FIG.

Here, the multi-valued dither method will be described with reference to FIG. The multi-valued dither method is an extension of the binary dither method to multi-valued (3 or more values), and multi-values it in relation to the number of threshold matrices smaller by one than the multi-valued number. In the embodiment of the present invention, since it is 16-value dither, the threshold matrix of the first layer to the fifteenth layer is used for 16-value conversion. FIG. 5 shows the threshold matrix (1) of the first layer and the threshold matrix of the fifteenth layer of the uppermost layer.
(2) is illustrated. Further, in FIG. 5, when the 0-251 level continuous tone image (3) is converted to the 0-15 level by 15 threshold matrices, a 16-value dither image (4) is obtained.

Next, returning to FIG. 2, when the printer code indicating the end of the page comes, the writing to the image data memory 13 is completed. If the printer engine 3 is ready, printing is started. At this time, the contents of the image data memory 13 for each color are not sent as they are, but the image expansion unit 15 and the gradation processing unit 16 are
Then, it is sent as a recorded image signal 6 to the printer engine 3 through the engine interface 17.

The image expansion unit 15 expands the image data for each color in accordance with the operation of the printer engine 3. B
Printing is performed in the order of k, C, M, and Y, but the image recording signal 6 required for printing Bk is composed only from the image data of Bk in the image data memory 13 and the information of the image discrimination memory 14, and other No C, M, Y image data is required. For other colors, the processing of the image decompression unit 15 can be performed only by the image data of itself and the information of the image discrimination memory 14.

FIG. 6 is a block diagram showing the configuration of the image expansion section 15 shown in FIG. 2. The image data signal 22 from the image data memory 13 is the image discrimination signal 21 from the image discrimination memory 14.
Thus, the demultiplexer 23 separates the binary image data and the multivalued image data. Then, the binary image data is processed by the binary data image decompression unit 24, the multi-valued image data is processed by the multi-valued data image decompression unit 25, and is combined by the multiplexer 26 to become the image expansion signal 27. This image extension signal 27 is 300D
It is sent to the gradation processing unit 16 as halftone image data of PI and 256 gradations.

In the binary image data, not only the binary data of 300 DPI is converted by the binary data image decompression unit 24 into data of 300 DPI and 256 gradations, but also the edge portion of binary characters and line drawings is smoothed. It is also converted. Multi-valued image data is 150 DPI in the multi-valued data image expansion unit 25, and 16-value dithered image data is 300 DPI, 256
After the processing of converting the gradation into continuous gradation is performed and the recording density and gradation of both the binary image data and the multi-valued image data are made uniform, the interpolation processing described below with reference to FIG. 7 is performed.

FIG. 7 shows the multivalued data image decompression unit 25 shown in FIG.
3 shows the contents of the interpolation processing of multi-valued image data in FIG. In FIG. 7, the bitmap (1) of the image discrimination memory 14 is all 1 and indicates that it is multi-valued image data. When the bitmap (2) of the image data memory 13 is represented by 16-valued expression, (3 ), 6, 5, 5, 4 from the upper left block to the lower right block. When this 16-value representation is multiplied by 17 to be converted into 256 values which are the number of gradations of the printer engine 3, they are 102, 85, 85 and 68, respectively, as shown in (4). In this state, the multi-valued image data formally has 256 gradations, but it is effectively 150 DPI, 16-valued data, and the block distortion is noticeable, and the image quality is not sufficient, so interpolation is performed to improve this. Perform processing.

That is, the data from the 16-valued representation is obtained by interpolating the pixels X, Y, and Z at the upper right, lower left, and lower right of the block with the upper left pixel of the block as a reference. Upper right pixel X
Averages 102 and 85 to 94. Similarly, the pixel Y at the bottom left is 9
4 and the lower right pixel Z has four levels 102, 85, 85, 68.
The average is 85. Other pixels are similarly obtained.

By this interpolation processing, the resolution of the halftone image is improved as shown in (5), the binary image data and the resolution point are unified, and the uniform image recording signal 6 of high image quality is obtained.

The binary data image expansion unit 24 also smoothes the edge portion of the binary image data. 8 is shown in FIG.
It is an explanatory view of the smoothing of the value data image decompression unit 24,
The contents of the Bk image data and the image discrimination memory 14 at the boundary of the binary image data memory 13 are shown. Since the bitmap (1) of the image discrimination memory 14 is all 0, all pixels are binary image data. When converting the binary image data into 8-bit 256 gradation information, 0 is set to 0 level and 1 is set to 255 level. However, at the boundary between binary image data, 0 is set to 0 level or 85 level and 1
The intermediate level is generated as 255 level or 170 level to obtain the continuous gradation reproduction of FIG. Several methods have been proposed as a method of smoothing a binary image. FIG. 8 (4) shows smoothed image data converted into information of 8-bit 256 gradations by this smoothing.

By repeating the above-mentioned image expansion processing, Bk
An image expansion signal 27 for one color is obtained. Image expansion signals are similarly obtained for other recording colors, and the image expansion unit 15 of FIG. 6 sends an 8-bit image expansion signal 27 and a 1-bit image discrimination signal 21 to the gradation processing unit 16.

The gradation processing unit 16 carries out processing such as image density adjustment, gamma correction, screen angle, etc., but the center of the processing is to cause uneven dot growth depending on the position of the pixel to cause the printer engine 3 This is a gradation modulation process for stabilizing the gradation. The principle of this gradation modulation processing is shown in FIG.

FIG. 9A shows the conventional gradation modulation of one pixel, in which dots of each pixel are uniformly grown. On the other hand, in the present embodiment, as shown in FIG. 9 (2), two growth patterns of a pixel to be dot-grown and a pixel to be grown later in two pixels are used to stabilize gradation. ..

Further, the density adjustment is performed based on the image density adjustment signal from the operation unit of the printer, and the characteristic curve showing the characteristics of the density adjustment is as shown in FIG. The shading is adjusted around.

In order to automate gamma correction, a predetermined image density pattern is formed by the printer engine 3 before printing on the printer, the image density is measured, and gamma correction characteristic information is obtained from the measured density data.

Further, since the gradation modulation process causes unevenness in dot growth, when printing is performed with the same gradation modulation pattern for each color, if the registration for each color does not match at all, moire between recorded colors is increased. Interference fringes called "images" are generated, and the image quality is greatly deteriorated.

In the color recorded image, the screen angle method is used to avoid the moire between the recorded colors.

That is, the image is divided into 4 × 4 blocks,
Each pixel is divided into two pixels, a pixel to be grown first and a pixel to be grown later. How to divide the two
As shown in FIG. 11, recording colors Bk, C, M, and Y are made different, and Bk is 45 °, C is 63.4 °, M is 26.4 °, and Y forms a screen angle of 0 °. Avoid moire due to interference.

The gradation processing unit 16 realizes gradation modulation, density adjustment, printer gamma correction, and screen angle processing with one table. FIG. 12 is a block diagram showing the configuration of the gradation processing unit 16. The image expansion signal 27 from the image expansion unit 15 is input to the image gradation conversion table 34 and becomes the image recording signal 6. Since it is necessary to change the gradation characteristics depending on the recording color, by inputting the recording color signal 31 to each of the priority pixel determination circuit 33 and the image gradation conversion table 34, gradation conversion according to each color can be performed. It has become. In addition to the recording color signal 31, the image address signal 32 is input to the priority pixel determination circuit 33, and the priority pixel 4-bit image address signal 32 is input.
The information about the position of the image data being processed in the 4 × 4 block is obtained by the following, the recording color signal 31 determines which recording color, and the priority pixel determination circuit 33 determines whether it is a priority pixel. Then, the priority pixel determination signal 35 is output.

On the other hand, in the image gradation conversion table 34, the CPU
The table is selected by the image discrimination signal 21, the recording color signal 31, and the priority pixel determination signal 35 under the control of 36, and the image expansion signal 27 is converted to the image recording signal 6 by referring to the table. The image recording signal 6 is converted into a level signal for actually driving the laser, for example, pulse width data. The image gradation conversion table is prepared for the following three for each color, one of which is a table for binary image data (image discrimination signal 21 is 0) and is generated by smoothing edges of binary characters and line drawings. It also handles intermediate levels. The other two are tables for halftone data (image discrimination signal 21 is 1), a table for pixels to be grown first and a table for pixels to be grown later.

In the present embodiment, in the halftone data processing of the gradation processing unit 16, the spatial position of the image data is separated into the pixel to be grown first and the pixel to be grown later, and the data is divided into pixels to be grown first. Is forcedly concentrated, the effect of generating a strong electric field in a micro area of the electrostatic latent image on the photoconductor is very large, which contributes to the improvement of gradation.

Next, a full color LBP in which the present invention is carried out
This will be described in detail with reference to the configuration diagram of FIG.

A full-color LBP for forming a color image to which an electrophotographic process technology is applied is formed by selectively irradiating a light beam corresponding to each color onto a photosensitive member having a photosensitive layer.
A plurality of electrostatic latent images respectively corresponding to specific components of a plurality of predetermined color components are developed with respective predetermined toners, and those single-color toner images are superposed to form a color on one transfer material. The method of forming an image is adopted.

In FIG. 13, 37 is an organic photoconductor (OPC).
Is a photoconductor in which a photosensitive layer such as is applied in a thin film form. The photoconductor 37 is rotated in the direction of arrow A by a drive motor (not shown). On the peripheral surface of the belt-shaped photoconductor 37, the charger 38, the exposure optical system 39, the black (Bk), the cyan (C), the magenta (M), and the yellow (Y) are arranged in the order of the photoconductor rotation direction indicated by the arrow A. Developing devices 40Bk, 40C, 40M, 40Y for the respective colors, an intermediate transfer body unit 41, and a photoconductor cleaning device 42 are provided. The charger 38 uniformly charges the photoconductor 37 by corona discharge. Reference numeral 43 is an exposure light beam of image data emitted from the exposure optical system 39.

In the laser beam printer, this exposure light beam
Reference numeral 43 is obtained by applying an image signal from the gradation processing unit 2 to the semiconductor laser (not shown) in which the image signal is light intensity modulated or pulse width modulated by a laser drive circuit (not shown). A plurality of electrostatic latent images corresponding to specific components of the plurality of predetermined color components are formed on the upper surface. Each color developing device stores a toner corresponding to each color.

The toner color is selected in accordance with each color, and the separating / contacting cam 44B is rotatably supported at its both ends on the main body of the machine.
k, 44C, 44M, and 44Y rotate in response to the color selection signal, and the selected developing device, for example, 40Bk is brought into contact with the photoconductor 37. Remaining developing devices not selected 40
C, 40M and 40Y are separated from the photoconductor 37.

The intermediate transfer body unit 41 has a seamless loop belt-shaped intermediate transfer body 45 made of a conductive resin or the like. Reference numeral 46 denotes an intermediate transfer member cleaning device for scraping off the residual toner on the intermediate transfer member 45.
While the composite image is formed on 45, it is separated from the intermediate transfer member 45, and abuts only during cleaning. Reference numeral 47 is a paper feed cassette that stores recording paper 48.

The recording paper 48 is sent from the paper feed cassette 47 to the paper feed path 50 one by one by a half-moon shaped paper feed roller 49. Reference numeral 51 denotes a transfer roller for transferring the composite image formed on the intermediate transfer body 45 to the recording paper 48, and rotates in contact with the intermediate transfer body 45 only when the composite image is transferred to the recording paper 48. A fixing device 52 forms a color image by fixing the toner image on the recording paper 48 with pressure and heat.

The operation of the electrophotographic apparatus having the above structure will be described below.

The photosensitive member 37 and the intermediate transfer member 45 are driven by respective drive sources (not shown), and are controlled so that their peripheral speeds become the same constant speed. In this state, first, corona discharge is performed in the charger 38 connected to the high voltage power source, and the surface of the photoconductor 37 is uniformly charged to about -700V to -800V.

Next, the photosensitive member 37 is rotated in the direction of arrow A, and an exposure beam of a laser beam corresponding to a predetermined black (Bk) of a plurality of color components is formed on the surface of the uniformly charged photosensitive member 37. When 43 is irradiated, the electric charge disappears in the irradiated portion on the photoconductor 37, and an electrostatic latent image is formed.

On the other hand, the developing device 40Bk containing the black toner that contributes to the development is a contact / separation cam according to the color selection signal.
It is pushed in the direction of arrow Bk by the rotation of 44 Bk and comes into contact with the photoconductor 37. With this contact, toner adheres to the electrostatic latent image portion formed on the photoconductor 37 to form a toner image, and the development is completed.

The developing device 40Bk, which has completed the development, has a separation cam 44.
By rotating Bk by 180 degrees, it moves from the contact position with the photoconductor 37 to the separated position (direction of arrow B '). The toner image formed on the photoconductor 37 by the developing unit 40Bk is transferred to the intermediate transfer body 45 by applying a high voltage to the intermediate transfer roller 53 arranged in contact with the photoconductor 37 for each color. Residual toner that has not been transferred from the photoconductor 37 to the intermediate transfer member 45 is removed by the photoconductor cleaning device 42.

Next, for example, when the color of cyan (C) is selected, the contact / disengagement cam 44C rotates, and this time the developing device 40C is moved to the photosensitive member 37.
In the direction of the arrow (3) to bring it into contact with the photoconductor 37 to start the development of cyan (C). In the case of a copying machine or printer using four colors, the above developing operation is sequentially repeated four times, and the intermediate transfer member 45
Toner images of four colors Bk, C, M, and Y are superposed on each other to form a synthetic toner image.

In the thus-formed synthetic toner image, the paper transfer roller 51, which has been separated so far, comes into contact with the intermediate transfer member 45, applies a high voltage to the paper transfer roller 51, and causes the paper feed cassette 47 to move under pressure. It is collectively transferred to the recording paper 48 sent along the paper transport path 50. Then, the recording paper 48 on which the toner image is transferred is sent to the fixing device 52, where it is fixed by heat and pressure and output as a color image. Residual toner on the intermediate transfer member 45 that has not been completely transferred onto the recording paper 48 by the paper transfer roller 51 is removed by the intermediate transfer member cleaning device 46.

By the above operation, recording of one image is completed, and a color-recorded image whose density is adjusted can be obtained.

The printer is not limited to the electrophotographic system using the laser beam of this embodiment, and may be a thermal transfer system, an inkjet system, or the like, which is the same electrophotographic system such as an LED system liquid crystal shutter system. And so on. Further, in the present embodiment, the color image is superposed on the intermediate transfer member, but it may be superposed on the photosensitive member or on the transfer paper.

[0059]

As described above, the image forming apparatus of the present invention performs the image discrimination processing according to the image data of the image type, so that the image memory becomes small in capacity, and the interpolation processing is performed. It is possible to unify the resolutions of image data of the above types and obtain a high-quality continuous tone recorded image.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of an image processing unit shown in FIG.

FIG. 3 is a flowchart of an image expansion unit shown in FIG.

FIG. 4 is an explanatory diagram of data writing in the image expansion unit shown in FIG.

FIG. 5 is a diagram illustrating a multi-value dither method.

6 is a configuration block diagram of an image decompression unit shown in FIG. 2. FIG.

FIG. 7 is an explanatory diagram of interpolation processing of multivalued data in the multivalued data image decompression unit shown in FIG. 6.

FIG. 8 is an explanatory diagram of binary data smoothing of the binary data image decompression unit shown in FIG.

9 is an explanatory view of the principle of the gradation modulation processing of the gradation processing unit shown in FIG.

FIG. 10 is a diagram showing a characteristic curve of density adjustment.

FIG. 11 is an explanatory diagram of a screen angle for each color for avoiding moire between recording colors.

12 is a configuration block diagram of a gradation processing unit shown in FIG.

FIG. 13 is a configuration diagram of a full color LBP in which the present invention is implemented.

FIG. 14 is a diagram illustrating the principle of a conventional binary dither method.

FIG. 15 is a circuit configuration diagram of a binary dither method.

[Explanation of symbols]

1 ... Image forming apparatus, 2 ... Image processing unit, 3 ... Printer engine, 4 ... Host computer, 5 ...
Printer code, 6 ... Image recording signal, 7 ... Recorded image, 11 ... Communication interface, 12 ... Image development unit,
13 ... Image data memory, 14 ... Image discrimination memory, 15
... image decompression unit, 16 ... gradation processing unit, 17 ... engine interface, 21 ... image discrimination signal, 22 ... image data signal, 23 ... demultiplexer, 24 ... binary data image decompression unit, 25 ... multi-value data image decompression Section, 26 ... Multiplexer, 27 ... Image expansion signal, 31 ... Recording color signal, 32
... Image address signal, 33 ... Priority pixel determination circuit, 34 ...
Image gradation conversion table, 35 ... Priority pixel determination signal, 36
... CPU, 37 ... Photoconductor, 38 ... Charging device, 39 ... Exposure optical system, 40 ... Developing device, 41 ... Intermediate transfer body unit, 42
... Photoconductor cleaning device, 43 ... Exposure light beam, 44 ... Separation cam, 45 ... Intermediate transfer member, 46 ... Intermediate transfer member cleaning device, 47 ... Paper cassette, 48 ... Recording paper, 49
... Paper feed roller, 50 ... Paper transport path, 51 ... Transfer roller,
52 ... Fixing device, 53 ... Intermediate transfer roller.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location H04N 1/40 F 9068-5C

Claims (1)

[Claims] 1. Image discrimination information for storing a halftone image as medium resolution multi-valued image data and a binary image as high resolution binary image data in an image data memory respectively, and image discrimination information for distinguishing the two image types. A storage unit and a function of converting the multi-valued image data and the binary image data into recorded image data of a predetermined format in accordance with the information from the image discrimination information storage unit and interpolating the multi-valued image data. An image forming apparatus comprising: an image conversion unit that has the image conversion unit; and an image recording unit that forms a recorded image using the recorded image data.