JP2959236B2 - Copier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital copying machine, a digital printer, and the like for printing multi-value read data.

[0002]

2. Description of the Related Art In a copying machine, when a plurality of originals are copied in a plurality of copies, sorting (sorting) for each copy is an essential function. For this reason, a mechanical sort using a sorter is performed. In a digital copying machine, various functions are enabled by storing image information of a read document. Therefore, a so-called electronic sort is performed (for example, see Japanese Patent Application Laid-Open No. 3-64783). This electronic sorting means that, for example, when three copies of three originals a, b, and c are copied, images are first read once in the order of a, b, and c, and the information of the three images is compressed and stored in memory. After that, decompression and recording are performed in the order of a, b, c, a, b, c, a, b, and c each time. As a result, it is possible to sort the copy sheets one by one by an electric means without using a mechanical sorter.

[0003]

In this electronic sort,
It is necessary to accumulate and read image information of a plurality of documents in a memory. In conventional electronic sorting, multi-valued image data is
Value, store it in compressed form, and when recording,
Binary image data obtained by expanding binary compressed data is recorded as it is. However, if the recording means can record multi-valued data, the multi-value recording means will be used as a binary recording means in the conventional electronic sorting, and the performance of the recording means will not be fully utilized. Further, if the multi-valued image data is stored in the memory as it is and the electronic sorting is performed, an enormous amount of memory is required, and a large amount of time is required for reading and writing, which is not practical. An object of the present invention is to perform electronic sorting using binary compressed data, and perform binarization corresponding to each of a halftone area and a non-middle length area so as to reproduce the original image more faithfully, It is another object of the present invention to provide a digital copying machine which restores binary data to multi-valued data corresponding to each area and performs recording using a recording means capable of recording multi-valued data.

[0004]

A copying apparatus according to the present invention comprises a reading means for reading an original image and outputting multi-valued image data, and a non-halftone image consisting of a character image or a photographic image. A determination unit that outputs a signal indicating whether the image is a halftone, and multi-valued image data read by the reading unit according to a halftone or non-halftone signal output from the determination unit. A binarizing unit for performing binarization corresponding to a halftone, and performing a binarization corresponding to a non-halftone for a non-halftone; a compression unit for encoding binarized image data; Storage means for storing the image data encoded by the means over a plurality of pages; storage means for storing a signal indicating whether the original image output from the determination means is non-halftone or halftone; Remembered in Decompressing means for decoding the decoded image data, first multi-level converting means for performing multi-level conversion on the decoded binary image data corresponding to halftone, and decoded binary image data Multi-level conversion means for performing multi-level conversion corresponding to non-halftones, and multi-level conversion by a first multi-level conversion means or a second multi-level conversion means from a signal stored in the storage means Switching means for switching whether to multi-value by the
Alternatively, copying means for printing on recording paper based on the reproduced image data multi-valued by the second multi-value converting means, and coded data stored in the storage means may be converted into binary image data for each page. And a sorter for repeatedly executing a predetermined number of copies of a cycle of decoding the image data and restoring it into multi-valued image data for printing.

[0005]

According to the present invention, the multi-valued read data of a plurality of originals are sequentially read, and the data are read in different ways according to whether the image is a halftone area composed of a photographic image or the like or a non-halftone area composed of a character image.
The binarized data is compressed, encoded, and stored in a memory. After decompressing the compressed data into binary data, the compressed data is further restored to multi-valued image data by different methods according to the halftone area or the non-halftone area,
This multi-valued image data is recorded. The processing for each page of decompression, restoration, and recording is repeated for a predetermined number of copies in a predetermined order for electronic sorting. This allows you to make high quality copies,
In addition, sorting is possible.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. (Configuration of Copying Machine) FIG. 1 is a schematic configuration diagram of a digital two-color copying machine with a facsimile according to an embodiment of the present invention.
The copying machine includes a scanning system 10, an image signal processing unit 20, a print processing unit 40, an optical system 60, an image forming system 70, an operation panel 90, and a facsimile unit 30.

The scanning system 10 has a function of exposing and scanning a document placed on a document table glass 18 and extracting reflected light from the document as electric signals by photoelectric conversion elements (CCDs) 16 and 17. The scanning system 10 includes an exposure lamp 11 for irradiating the original, mirrors 12 and 13 for changing the optical path of the reflected light from the original, a lens 14 for condensing the reflected light, and two photoelectric conversion elements for color discrimination. It has a dichroic prism 15 that guides a specific color (red) and its complementary color, and photoelectric conversion elements 16 and 17 that generate an electric signal according to the received light. A scanner 19 moves in parallel with a platen glass 18, The original is exposed and scanned at the time of movement in the direction of the arrow in the figure.
The conversion into an electric signal is performed for the specific color and the other colors by the two photoelectric conversion elements 16 and 17. In the following, an example of a two-color printer using two colors of red and black (the sum of red and its complementary color) will be described. However, a similar function can be achieved by a combination of black and another color or blue and red. Demonstrate.

The image signal processing unit 20 (see FIG. 4) processes the image signals output from the two photoelectric conversion elements 16 and 17 to discriminate between a specific color and other colors, and sends the color to the facsimile unit 30. Output as image data with information.

The facsimile unit 30 (see FIG. 5)
The X main unit 32 performs a communication function as an original facsimile, has an image restoration unit 31, performs binary / multi-value conversion, scaling processing, etc., and outputs the image data with color information to the print processing unit 40. I do.

[0010] The print processing unit 40 detects the 2
The image data with color information of the color is received, the image data is separated into two semiconductor lasers according to the image data, and the image data is delayed and sent to the second semiconductor laser by the positional deviation of the two lasers. Has functions.

The optical system 60 has a function of forming an electrostatic latent image on the photosensitive drum 71 by laser light, and includes semiconductor lasers 61 and 62 (see FIG. 12) and an LD drive circuit 63.
(See FIG. 12), a laser head 65 having a collimator lens, a combining half mirror, and a polygon mirror.
, A lens 69, a mirror 67a, a mirror 68 for separating the two laser beams, and
It is composed of mirrors 67b and 67c that guide the light upward. The semiconductor lasers 61 and 62 are driven by an LD drive circuit 63 to independently generate laser beams modulated by image data output from the print processing unit 40, and the respective laser beams are combined by the half mirror 63. You. The direction of the synthesized laser light is changed by the polygon mirror so as to scan the photosensitive drum 71 in the line direction. The deflected synthesized laser light is condensed by a lens 69 so as to form an image on the photoreceptor drum 71, the direction is changed by a mirror 67 a, and further divided into two laser lights by a separation mirror 68. Inside mirror 67b, 67c
Through the photosensitive drum 71.

The image forming system 70 has a function of developing the electrostatic latent image formed on the photosensitive drum 71 and transferring and fixing the latent image on paper. The image forming system 70 includes a developing / transfer system, a transport system, and a fixing system. Be composed. The developing / transfer system includes a photosensitive drum 71 and a first charger 7 for uniformly charging the surface of the photosensitive drum 71.
2a, a first developing device 73a for storing the red toner, a second charger 72b for charging the photosensitive drum 71 again for the second exposure, and a second developing device 73b for storing the black toner
And a transfer charger 74 for transferring the developed toner image onto paper, a cleaning unit 76 for removing toner remaining on the surface of the photosensitive drum 71, and the like. The transport system is a system that supplies and transports the print paper, and includes cassettes 80a and 80b that store the paper, a paper guide 81 that guides the paper extracted from the cassette, a timing roller 82 that provides a timing for transporting the paper to a transfer unit,
There is a belt 83 for transporting the sheet to the fixing system. The fixing system thermally presses the toner image transferred onto the print paper between the fixing rollers 84, and the paper on which the toner is fixed is discharged from the machine by discharge rollers 85.

As shown in FIG. 2, the operation panel 90 includes a button input section and a display section. The button input section includes a numeral button 91, a start button 92, and a magnification setting button 9.
3. Sort button 94, facsimile mode button 95
The display unit has a display unit 96 for the set number or the destination FAX number, and mode displays 97, 98, and 99 for magnification, sorting, and copy / FAX.

(Control System) FIG. 3 is a block diagram of a control circuit. The control circuit of the copying machine is mainly composed of six CPUs. Each CPU has its own system RO
M, a system RAM. The first CPU 9 analyzes a signal from a switch or a numeric keypad of the operation panel 90 or data transmitted by communication, and performs processing for displaying and transmitting the input data. Second
The CPU 2 receives image data from the photoelectric conversion elements 16 and 17 and performs color discrimination in addition to normal image processing such as shading correction, scaling, and dither processing, and supports color (red) and black toner development. The print signal is converted into a write signal to be output, and control for outputting data to the print processing unit 40 is executed. 3rd CP
U1 is a CPU that controls the operation of the scanning system 10. The fourth CPU 6 includes a recording unit, that is, an image forming system 70 and an optical system 60.
The CPU controls the first and second charging of the photosensitive drum 71, writes image data generated in cooperation with the print processing unit 40, and develops two color (red) and black toners Control of print-related operations such as paper feed control. The fifth CPU 5 controls the coordinating role of the entire copying machine, and controls the CP via a serial I / O or the like.
The timings of the U are adjusted and the operation mode is determined. The sixth CPU 3 controls a facsimile unit, that is, a communication block, and performs conversion between image data and code data, transmission and reception of a communication protocol, conversion of an NCU unit, and the like.

(Image Processing Circuit) FIG.
0 shows a block diagram. In the two-color printer of this embodiment, the image data is processed into a specific color and other colors, and is output to the image restoring unit 31 as read image data. The reflected light of the original is separated by the dichroic prism 15,
Two CCDs 16 and 17 are reached. The photoelectric conversion signals of the specific color detected by the main CCD 16 and the sub CCD 17 and the complementary color thereof are respectively subjected to the first and second analog processing / A / D
The digital values are converted by the conversion units 901 and 904,
The first and second shading correction units 902 and 905 correct variations in the main scanning direction. Next, the two-color image data is input to the color discriminating unit 908, and the color discriminating unit 908 determines whether the pixel being processed is a specific color (red) or its complementary color from the specific color image data and the complementary color image data. It is determined whether or not there is, and the result is output from the selector 9 of the image data
Output to 12 selection inputs. The two-color image data is input to the addition unit 911 of the image data synthesis unit 910, and the added value (black image data) is input to the selector 912 together with the specific color image data. In the image data synthesizing unit 912, when the color discrimination unit 908 determines that the color is the specific color, the specific color image data (the shading unit 90)
2 outputs) is selected. On the other hand, when it is determined that the color is not the specific color, the color is considered to be black, and the sum of the specific color image data and the complementary color image data (output of the adder 911), that is, black image data is selected. The image data selected by the selector 912 using the color determination result is then converted to a density correction unit 913.
After performing undercolor removal and density reproducibility correction, the filtering unit 914 performs an edge enhancement process and a smoothing process, and outputs the result to the image restoration unit 31 of the facsimile unit as read image data.

(Control of Image Data Flow in Facsimile and Image Restoration) FIG. 5 is a block diagram of the facsimile unit 30. The facsimile unit 30 (see FIG. 5)
The AX main unit 32 performs the functions (communication, compression, decompression, etc.) of the original facsimile, and also has an image restoration unit 31 for performing binary / multi-value conversion, scaling processing, and the like. Output as image data with color information. The facsimile unit in the present embodiment is characterized in that the image restoration unit 31 also controls the flow of image data in addition to the function of the original facsimile, as described below.

The configuration of the FAX body 32 is the same as that of a conventional facsimile. The image restoration unit 31 includes a multi-value → binary conversion unit 103 for converting multi-value data into binary data, a binary → multi-value conversion unit 108 for converting binary data into multi-value data,
Multi-level image density converter 1 for converting the density of multi-level image data
04, a binary image density conversion unit 105 for converting the density of binary image data, a first and a second switching units 101 and 110 for switching data, and a selector 10
6, 107. These functions are described below.

[During Copying] The read image data obtained by the image processing circuit 20 of the reading unit passes through the first switching unit 101 and the selector 106, and the density is converted by the multi-value image density conversion unit 104 according to a predetermined magnification. The data is converted (magnified) and output to the recording unit as recording image data. The read color information obtained by the reading unit is supplied to the first switching unit 101 and the selector 107.
Then, the binary image density conversion unit 105 performs density conversion according to a predetermined magnification, and outputs the converted color information to the recording unit. At the time of the same magnification, the multi-value image density conversion unit 104 and the binary image density conversion unit 105 perform a process of × 1.0.

[During Facsimile Transmission] In facsimile transmission, automatic reduction is performed according to the paper size. The feature of this embodiment is that at the time of this automatic reduction, a binary image is once restored to a multi-valued image, and density conversion (magnification) for the multi-valued image is performed.
Processing. As a result, the density conversion of the pseudo halftone binary image can be achieved with high image quality.

The read image data obtained by the reading unit is the first image data.
After passing through the switching unit 101, the image data is converted into binary image data in the multi-value → binary conversion unit 103. The binarized image data passes through the second switching unit 110 and passes through the first page memory 121.
Is stored in The read color information obtained by the reading unit passes through the first switching unit 101 and the second switching unit 110 and is stored in the second page memory 122. Binary image data stored in first page memory 121 and second page memory 122
Are compressed by the first compression / expansion unit 131 and stored in the compressed data memory 123.

When all the original image information (compressed binary image data and read color information) is stored in the compressed data memory 123 in this manner, the original image information is stored in a compression size determined when the receiving side has a communication size and communication is established. It is converted into document image information according to the method. That is, the compressed binary image data of the document image information is expanded again by the re-compression processing unit 133 to the first page memory 121 and the second page memory 122. The decompressed binary image data passes through the second switching unit 110, is input to the binary-to-multi-value conversion unit 108, and is restored to a multi-value image. After passing through the selector 106, the multi-value image density conversion unit 104 performs density conversion so as to have an image size corresponding to the recording size on the receiving side. Then, through the first switching unit 101, multi-valued →
The image is binarized by the binary conversion unit 103 and stored in the second page memory 132. The image data stored in the second page memory 132 is sequentially recompressed by the recompression processing unit 133 and then stored in the compressed data memory 123.
Processing to HDLC standard by MPSC137 and MO
The data is modulated by the DEM 138 and transmitted to the telephone line through the NCU 139.

On the other hand, in the present embodiment, the compressed read color information of the original image information is transmitted after the binary image data is transmitted in page units. The read color information is expanded into the first page memory 121 by the re-compression processing unit 133, passes through the second switching unit 110 and the selector 107, and after the density conversion by the binary image density conversion unit 105, the first switching unit 101 Second
The data passes through the switching unit 110 and is stored in the second page memory 132. Subsequent processing is the same as in the case of the binarized image data.

In this embodiment, a scaling process for multi-valued image data at the time of copying and a scaling process for binary image data at the time of automatic reduction in facsimile transmission (as described above, "Conversion after conversion to data" is performed using the same scaling unit for multi-valued image data (ie, multi-value density conversion unit 105). As a result, it is not necessary to provide the variable magnification processing unit twice.

[At the time of facsimile reception] The received image information passes through the NCU 139 in reverse to that at the time of facsimile transmission.
The signal is demodulated by the ODEM 138, subjected to reverse processing by the HDSC standard in the MPSC, and stored in the compressed data memory 123. When all image information has been received, a recording operation starts. That is, the compressed binary image data and color information stored in the compressed data memory 123 are respectively converted by the second compression / decompression unit 132 into the first page memory 121,
The data is expanded in the second page memory 122. The binary image data expanded in the first page memory 121 is restored to a multi-valued image by a binary-to-multi-value conversion unit 108, and the selector 106 and the multi-valued image density conversion unit 104 (here, a x1.0 The image data is transmitted to the recording unit through the first switching unit 101 as recording image data. The color information expanded in the second page memory 122 is supplied to the second switching unit 110, the selector 107,
The image data is sent to the recording unit as recording color information through a binary image density conversion unit 105 (here, a magnification change process of × 1.0 is performed) and a first switching unit 101.

[At the time of memory copy in multi-copy and electronic sort] The memory copy here means that image information is temporarily stored in a memory, and a copy is made while reading the image information. As a method of storing image information in the memory, there are a method of storing the actual image as it is (multi-copy) and a method of storing it after compression (electronic sorting).

The storage of the actual image is performed so that the scanning of the reading unit is performed at the time of multicopy. The data flow at this time will be described. The read image data is
After passing through the first switching unit 101 and converted into a binary image by the multi-valued to binary conversion unit 103, the image is sent from the second switching unit 110 to the first page memory 121 and stored for one page. The read color information passes through the first switching unit 101 and the second switching unit 110, and passes through the second switching unit 101 and the second switching unit 110.
It is stored in the page memory 122. When the storage of the image information for one page is completed, the restoration ON signal (H level for the halftone original) is taken into the CPU 3 and the same content is output on the restoration execution signal. First and second page memories 12
The image information stored in 1, 122 is read out each time one sheet is recorded. The binary image data enters the binary-to-multi-value conversion unit 108 through the second switching unit 110, is multi-valued, passes through the selector 106, and is converted by the multi-value image density conversion unit 104 into a density corresponding to a predetermined magnification. After receiving the conversion, the data is output to the recording unit as recording image data through the first switching unit 101. The color information passes through the second switching unit 110 and the selector 107, undergoes density conversion according to a predetermined magnification by the binary image density conversion unit 105, and is output to the recording unit as recording color information through the first switching unit 101. You.

On the other hand, the compression of the image information into the memory after the compression is performed in order to perform the electronic sorting using the memory. Here, the electronic sort means that, for example, when three copies of three originals a, b, and c are copied, a, b, c
Once the image is read in the order of, the three image information is compressed and stored in the memory, and then decompression and recording are performed in the order of a, b, c, a, b, c, a, b, c each time (For example, see Japanese Patent Application Laid-Open
No. 4783). This allows sorting by electrical means without using a mechanical sorter. The data flow at this time will be described below.

At the time of reading, the read image data input from the reading unit passes through the first switching unit 101, is converted into a binary image by the multi-value → binary conversion unit 103, and then is read by the second switching unit 11.
From 0, it is sent to the first page memory 121 and stored. Similarly, the read color information input from the reading unit passes through the first switching unit 101 and the second switching unit 110, and is stored in the second page memory 122. When the storing of the image information for one page in the first and second page memories 121 and 122 is completed, the restoration is turned on.
A signal (H level when the document is a halftone original) is taken into the CPU 3. First and second page memories 121 and 122
Are compressed by the first compression / expansion unit 131 and stored in the compressed data memory 123. This operation is repeated for a predetermined number of documents.

At the time of recording, the first document information of the document information stored in the compressed data memory 123 is decompressed and
The value image data is expanded in the first page memory 121, and the color information is expanded in the second page memory 122. Restoration of the first page O
The same content as the N signal is transmitted as a restoration execution signal. The binary image data in the first page memory 121 passes through the second switching unit 110 and is converted into a multi-value by the binary-to-multi-value conversion unit 108.
After passing through the selector 106 and undergoing density conversion by the multi-valued image density conversion unit 104 according to a predetermined magnification, it passes through the first switching unit 101 and is output to the recording unit as recording image data. That is, after the binary compressed image data stored in the compressed data memory 123 is decompressed into a binary real image, as a feature of the present embodiment, it is further restored to multivalued image data before recording. The color information of the second page memory 122 is stored in the second switching unit 1.
10, through the selector 107, the binary image density conversion unit 10
5, after the density conversion according to the predetermined magnification, the first switching unit 10
1 and output to the recording unit as recording data. One copy is recorded by sequentially performing the above-described operations on all predetermined documents. Furthermore, by repeating the above operation for a predetermined number of sheets, a plurality of sorted copies can be obtained.

Here, at the time of reading, the first copy is recorded in the same manner. For this purpose, the read document image data sent from the first switching unit 101 to the multi-valued-to-binary conversion unit 103 is simultaneously transmitted to the selector 106,
The multi-valued image density conversion unit 104 outputs the read color information through the first switching unit 101 as recording image data, and simultaneously reads the read color information sent from the first switching unit 101 to the second switching unit 110 with the selector 107 and the binary image density conversion unit. 105, first switching unit 10
1 to output as recording color information.

In this embodiment, the processing from the multi-valued image to the compressed image is performed after the multi-valued data is converted into the binary data.
The compression (MH, RH, etc.) is performed, and the processing from the compressed image to the multi-valued image is performed. After the decompression (MH, RH, etc.), the binary data is converted into the multi-valued data. You may. For example, a multi-valued image compression method such as the ADCT method or the ADPCM method may be used.

[Improvement of Density Conversion (Magnification)] As described above, in the electronic sorting of this embodiment, after the binary compressed image data is expanded / compressed, it is further multivalued and then recorded. Therefore, density conversion (variable magnification) is also performed on multi-valued image data. Similarly, in automatic reduction of facsimile transmission, density conversion is performed after decompressing binary compressed image data into multivalued image data. As described in the following example, there is a difference in the processing result between the density conversion for the multi-valued image data according to the present embodiment and the density conversion for the binary image by the conventional electronic sorting or the automatic reduction transmission.

FIG. 6 shows an example of a case where the multi-valued image data is reduced by a factor of two and a case where the multi-value image data is enlarged by a factor of two. It can be said that the processing in this case is realized by smoothing with the peripheral pixels. At the time of 1/2 reduction, the following calculation is performed. D ₁ (0,0) = {D ₀ (0,0) + D ₀ (0,1) + D ₀ (1,0) + D ₀ (1,1)} / 4 where D ₁ is the density conversion Represents the latter data, D ₂ is
Represents data before density conversion. At the time of double magnification, the following calculation is performed. D ₁ (0,0) = D ₀ (0,0) D ₁ (0,1) = {D ₀ (0,0) + D ₀ (0,1)} / 2 D ₁ (1,0) = { D ₀ (0,0) + D ₀ (1,0)｝ / 2 D ₁ (1,1) = {D ₀ (0,0) + D ₀ (0,1) + D ₀ (1,0) + D ₀ ( 1,1)｝ / 4

On the other hand, FIG. 7 shows a comparative example in which the binary image data is similarly reduced by 1/2 times and enlarged by 2 times. The binary image is a binary image even after the density conversion. At the time of 1/2 reduction, binarization is necessary after smoothing processing with peripheral pixels.
At the time of double enlargement, the connection state of pixels is further emphasized, and smoothing processing is required by an appropriate logical filter. It can be said that at most a binary image other than the pseudo halftone image should be referred to at the same time. However, a complex process is required for the pseudo halftone image, for example, by referring to pixel data in the surrounding area. It should be noted that the scaling of the binary image here refers to a binary image that is not a pseudo halftone. These density conversion techniques are known, and what is described here is that there is a difference in the processing result between the binary image and the multi-valued image even in the density conversion.
Therefore, it is possible to prevent image deterioration, occurrence of moire, and the like.

(Multi-valued to binary conversion) FIG.
FIG. 4 is a block diagram of a multi-level-to-binary conversion unit 103; The area discriminating unit 204 uses the output of the 5 × 5 Laplacian secondary differential filter as shown in FIG. Therefore, 5 × 5
The matrix memory 200 stores image data for conversion. As shown in FIG. 10, in the region separating unit 204,
The output of the secondary differential filter is compared with a fixed value. If the output is less than the fixed value, it is determined that the image is a halftone. By doing so, the halftone (H
Level) or non-halftone (L level) is given for each pixel. The simple binarization unit 201 simply binarizes the multi-valued image data with a substantially constant threshold value, assuming that the multi-valued image data is a non-intermediate image such as a character document. Pseudo halftone binarization section 20
In 2, the pseudo halftone binarization is performed on the assumption that the multivalued image data is a halftone image such as a photograph. These two binarized image data are selected by the selector 203 in accordance with the output of the above-described region separation unit 204 (determination result = halftone)
(H level) selects the output of the pseudo halftone binarization unit 202) and is output as binarized image data. On the other hand, the output of the segmentation unit 204 is counted in the halftone pixel counting unit 205 in units of pages, and when an eight-fold value is larger than the total number of pixels (when the count value itself is larger than 1/8 of all pixels) ), Assuming that there is a halftone area, and
To level. This restoration ON signal is taken in by the CPU 3, and the restoration execution signal output from the CPU 3 in accordance with this signal is converted into a binary-to-multi-value conversion unit 108 during recording (FIG. 11).
Will be used.

(Binary to Multi-Value Conversion) FIG. 11 is a block diagram of the binary to multi-value conversion unit 108 of the image restoration unit 32. The restored binary image data is input to the first matrix memory 300, and data of 15 pixels in the main scanning direction × 18 pixels in the sub-scanning direction is stored. Based on the stored pixel data,
Each process of halftone restoration, image area discrimination, and simple multi-value conversion is executed by the halftone image restoration unit 301, image area discrimination unit 302, and simple multi-value conversion unit 303, respectively. Among them, the halftone image restoring unit 301 refers to data of 15 pixels in the main scanning direction × 15 pixels in the sub-scanning direction, and the image area determination unit 302 determines that 12 pixels in the main scanning direction × 12 pixels in the sub-scanning direction. Refer to the data of The reason why the first matrix memory 300 is large in the sub-scanning direction is that the image area refers to the intermediate discrimination result of 9 pixels in the main scanning direction × 17 pixels in the sub-scanning direction by the comprehensive discriminating unit 312 in the discriminating unit 302. This is because the pixels processed by the tonal image restoration unit 301 and the image area determination unit 302 are shifted by 5 pixels in the sub-scanning direction. The simple multi-value processing unit 303 performs a process of simply applying the binary white and black pixel data to the white and black data in the multi-value expression. In the halftone image restoration unit 301,
A process of restoring multi-valued image data from a plurality of binary image data is performed. It comprises a smoothing unit 305 for obtaining a smooth component, an edge emphasizing unit 306 for obtaining an edge emphasizing component, and an edge area detecting unit 307 for determining whether or not the pixel belongs to an edge area. The multi-level image data is restored in the unit 308. The image area determination unit 302 determines how much the processing pixel belongs to the non-halftone area or the halftone area. For this discrimination, first, a discrimination value is obtained for each pixel by the adjacent discrimination unit 309 and the systematic halftone discrimination unit 310, and the obtained discrimination value is stored in the second matrix memory. A final multi-valued area discrimination signal is obtained by the overall discriminating unit 312 from the discrimination value. Using the area determination signal thus obtained,
The halftone-non-halftone mixing unit 304 mixes the output from the halftone image restoring unit 301 and the output from the simple multi-value processing unit 303 to obtain restored multi-valued image data.

However, if the restoration execution signal from the CPU 3 is at L level, only the non-halftone data will be selected. This is because the restoration execution signal at the L level means that the restoration ON signal is at the L level for the document image, the document does not have a predetermined amount of halftone area, and the multi-value restoration process is not performed. This is because it is considered preferable to simply perform binary recording.

(Driving of Two-Color Semiconductor Laser) In the two-color printer of this embodiment, red and black printing are performed. The image information output from the image restoration circuit 31 is input to the LD drive circuit 63, and the semiconductor laser 16,
17 are controlled. Here, the red image data is exposed first, and then the black image data is exposed. The reason why the black image data is delayed is that the downstream developing unit 72a needs to be made of black toner due to the problem of color mixing.

FIG. 12 is a block diagram of the LD drive circuit 63. The recording image data is separated into red image data (specific color) and black image data by the color separation unit 631 according to the recording color information. If the recording color information is “1” (red), the color separation unit 6
The output A of 31 outputs the value of the input X (recorded image data) as it is, and the output B outputs a zero value that does not emit laser. Output B if recording color information is “0” (black)
Outputs the value of the input X, and the output A becomes zero.

The black image data output from the output B is temporarily stored in a line memory 634, which is a FIFO memory, in real time because it is delayed by a predetermined line. Here, the black image data is multi-valued data, but is binarized by the second multi-value → binary conversion unit 633 and stored in the line memory 634. The line memory 634 has the number of lines corresponding to the displacement of the position where the output from the first semiconductor laser 16 and the output from the second semiconductor laser 17 arrives on the photoconductor in the sub-scanning direction. In the main scanning direction, the number of pixels is equal to the number of pixels for laser scanning. The binary image output from the delay line memory 634 is restored in real time again to multi-level image data by the second binary-to-multi-level conversion unit 635, and is sent to the second laser control unit.

The reason why the multi-valued image data is converted into binary data and stored in the delay line memory 634 is that the deviation between the exposure positions of both semiconductor lasers is 50 mm or more, which is close to 800 lines at 400 DPI. Equivalent
This is because if the multivalued data is stored as it is, the capacity of the line memory is too large. For example, if the multi-valued image data is 8 bits, the capacity of the delay memory can be reduced to 1/8 by compressing the data into binary data. The red image data thus obtained and the black image data delayed by a predetermined line are
The first laser controller 632 and the second laser controller 6 respectively
36, and drives the first semiconductor laser 61 and the second semiconductor laser 62, respectively.

In this embodiment, the compressed image data is binary image data. However, if the compression and decompression processing can be performed in real time, the present invention is not limited to this. Note that the second multi-valued-to-binary conversion unit 633 and the second binary-to-multi-valued conversion unit 635 of the present embodiment correspond to the first multi-valued-to-binary conversion unit 103 of the image restoration unit 31 described above. This is equivalent to the first binary-to-multi-value conversion unit 108.

[0043]

According to the present invention, depending on whether the image is a half-tone area such as a photographic image or a non-half-tone area such as a character image,
Each of the binarized data is binarized by a different method, the binarized data is compressed and encoded, stored in a memory, and the stored compressed image data is decompressed into binary image data. Depending on whether the image data is a halftone area or a non-halftone area, the image data is restored to multivalued image data by different methods and then recorded. As a result, the performance of a printer capable of multi-value recording can be sufficiently obtained.
Whether the image is restored as halftone or non-halftone is determined by using the same area data as the data of the discrimination area used when binarizing the multivalued image data, and converting the binary image data into a multivalued image. Therefore, a copy very close to the original image can be obtained. Also, at the time of electronic sorting, the conversion unit that expands the compressed image data into binary image data using the encoded compressed image data and further uses the conversion unit to restore the multi-valued image data is used repeatedly. There is no need to increase it, and the hardware configuration can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic structural view of a copying machine with a facsimile.

FIG. 2 is a diagram of an operation panel.

FIG. 3 is a block diagram of a control unit.

FIG. 4 is a block diagram of an image processing circuit.

FIG. 5 is a block diagram of a facsimile unit.

FIG. 6 is a diagram of density conversion of binary data.

FIG. 7 is a diagram of density conversion of multi-value data.

FIG. 8 is a block diagram of a multi-value → binary conversion unit.

FIG. 9 is a diagram of a secondary differential filter.

FIG. 10 is a diagram of comparison using a secondary differential filter.

FIG. 11 is a block diagram of a second-order to multi-value conversion unit.

FIG. 12 is a block diagram of an LD drive circuit in the recording unit.

[Explanation of symbols]

31: image restoration unit, 40: print processing unit, 70: image forming system, 71: photosensitive drum, 108: binary to multi-value conversion unit, 123: compressed data memory, 131, 13
2: Compression / expansion device.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Munehiro Nakatani Minorta Camera Co., Ltd., Osaka Kokusai Building 2-3-13 Azuchicho, Chuo-ku, Osaka-shi, Osaka (72) Inventor Shigenobu Fukushima Azuchi, Chuo-ku, Osaka-shi, Osaka 2-3-3, Osaka-cho, Osaka International Building Minolta Camera Co., Ltd. In-house (56) References JP-A-61-148971 (JP, A) JP-A-3-64783 (JP, A) JP-A-1-147778 (JP) , A) JP-A-63-309064 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H04N 1/21 H04N 1/00-1/00 108 H04N 1/40-1 / 409

Claims (1)

(57) [Claims] 1. A reading means for reading a document image and outputting multi-valued image data, and a discriminator for outputting a signal indicating whether the document image is a non-halftone consisting of a character image or a halftone consisting of a photographic image or the like. Means, the multi-valued image data read by the reading means is subjected to halftone and non-halftone signals output from the discrimination means, and in the case of halftone, binarization corresponding to halftone is performed. For halftone, binarization means for performing binarization corresponding to non-halftone, compression means for encoding binarized image data, image data encoded by the compression means for a plurality of pages Storage means for storing a signal indicating whether the document image output from the determination means is non-halftone or halftone, and decoding encoded image data stored in the storage means. Evolving growth Length means, first multi-level conversion means for performing multi-level conversion of decoded binary image data corresponding to halftone, multi-level conversion of decoded binary image data corresponding to non-halftone level And a switching means for switching between the signal stored in the storage means and the first multi-value means or the second multi-value means. Copying means for printing on recording paper based on the reproduced image data multi-valued by the first or second multi-value converting means; and coded data stored in the storage means for each page. A copying apparatus comprising: sorting means for repeatedly executing a predetermined number of copies of a cycle of decoding into binary image data and restoring and printing multi-valued image data.