JPH04277979A - Copying machine - Google Patents

Abstract

PURPOSE:To store area information of a character with high efficiency. CONSTITUTION:Each R, G, B picture data is received by a picture compression section 102, which encodes the picture data, the coded picture data is stored in a picture memory 103, a picture expansion section 104 decodes the stored picture data and a post picture processing section 109 processes the decoded picture data by one of plural picture processing methods. Upon the receipt of each R, G, B picture data, a character area deciding circuit 105 decide the property of the picture based on the received picture data, that is, the presence of a character area, a run length coding circuit 106 codes the information of the character area whose presence is confirmed and an area memory 107 stores it, a run length decoding circuit 108 decodes the coded information and the picture processing method of the post picture processing section 109 is revised based on the decoded information.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying apparatus that reads and processes an original and reproduces it on a recording medium, and more particularly to a copying apparatus that has a memory for storing image signals.

0002

2. Description of the Related Art Conventionally, a copying apparatus has been proposed which reads an image with a line sensor, converts it into a digital signal, performs image processing, and forms a copy output on a recording medium. Some of these devices have an image memory and are configured to once store a document image and then output it.

[0003] Furthermore, in conventional color copying machines,
In order to eliminate the color blurring of text that occurs due to misalignment in document reading or misalignment in printing, the printer is configured to extract text areas from the document and apply image processing suitable for text documents to those areas. There are also suggestions.

0004

SUMMARY OF THE INVENTION However, in the conventional example described above, when it is configured to have an image memory and perform character processing, the following problems arise. When performing character processing, it is necessary to determine the character area that requires processing, but there are methods to determine the area when writing image information to memory and store the results together with the image data, and a method to store the results in memory. It is necessary to use one of the methods of determining when reading out the image signal that has been used.

[0005] In the method of determining when reading from memory, a plurality of determination means are required for the number of outputs, and it is necessary to match the determination result with the delay amount of the image signal.
This is disadvantageous in terms of cost. On the other hand, in the method of determining the area in advance before writing to the memory, in order to make the area signal and the image signal correspond to each other in the memory, the cell size of the same size (e.g. 4 x 4 pixels) or the cell size of the image signal I was trying to save the cell size as an integer multiple of the size.

By the way, character areas generally have the characteristic that they are locally concentrated in an image, and therefore the amount of information originally required to memorize the location of a character area is smaller than that of an image signal. There are far fewer. This means that the memory capacity for storing area information is much smaller than that of an image memory. However, in the conventional method of matching the storage sizes of the image memory and area memory, a storage capacity that is larger than the originally required capacity is allocated to the area memory. In other words, a memory with a capacity that is not originally necessary is used, which has the drawback of increasing the cost of the device.

The present invention has been made in view of the above-mentioned drawbacks of the conventional example, and its object is to provide a copying apparatus that can efficiently store character area information.

[0008]

[Means for solving the problem] Solving the above problems,
In order to achieve the object, a copying apparatus according to the present invention includes an input means for inputting image data, an encoding means for encoding the image data inputted by the input means, and an encoding means for encoding the image data input by the encoding means. storage means for storing converted image data; decoding means for decoding the image data stored in the storage means; and image data decoded by the decoding means using one of a plurality of image processing methods. an image processing means for processing, a determining means for determining the nature of the image based on the image data inputted by the input means, and a changing means for changing the image processing method based on determination information of the determining means. It is characterized by

[0009]

[Operation] According to this configuration, the input means inputs image data, the encoding means encodes the image data inputted by the input means, the storage means stores the image data encoded by the encoding means, and the encoding means encodes the image data input by the input means. The processing means includes a decoding means for decoding the image data stored in the storage means, and a processing means for processing the image data decoded by the decoding means using one of a plurality of image processing methods, and the determination means is an input means. The nature of the image is determined based on the input image data, and the changing means changes the image processing method based on the determination information of the determining means.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. (First Embodiment) FIG. 1 is a block diagram showing the structure of a first embodiment of a copying apparatus according to the present invention. In the same figure,
100 is a line sensor, 101 is a pre-image processing unit, 102
103 is an image compression unit, 103 is an image memory, 104 is an image expansion unit, 105 is a character area detection circuit, 106 is a run-length encoding circuit, 107 is an area memory, 108 is a run-length decoding circuit, and 109 is a post-image processing unit , 110 is a laser drive circuit.

The light reflected from the original is transmitted to the line sensor 100.
and is converted into color-separated electrical signals. The image signal converted here is input to the pre-image processing unit 101, where it is converted into a digital signal and subjected to processing such as shading correction and color correction to become an RGB (red, green, and blue) signal. The RGB signal is compressed to 1/8 the amount of information by vector quantization in the image compression unit 102 and written into the image memory 103. The image memory 103 has a storage capacity sufficient to store at least one screen worth of images in a compressed state. 8 bits per pixel, 4
00DPI (print density of 400 dots per inch)
The amount of data for an A3 document is approximately 90 megabytes. Since the compression rate in the image compression section is 1/8, approximately 12 megabytes of storage is required. The image data once stored in the image memory 103 is read out from the memory and then transferred to the image decompression unit 10.
4, the original image density is restored. On the other hand, the character area determination circuit 105 performs area determination for character processing at a stage before encoding the RGB signal. The determination result is compressed by the run-length encoding circuit 106 and stored in the area memory 107. The compression ratio in this case depends on how the character area is scattered, but since the parts where characters are clustered are not so scattered, they can be compressed efficiently.
Even for all three originals, the data amount after compression is about 256 kilobits, which is sufficient for practical use. The region signal read from the region memory is restored to its original density by the run-length decoding circuit 108. The restored image signal and area signal are subjected to processing such as density conversion, masking correction, UCR (inking), and γ correction in a post-image processing unit 109. At that time, when an area signal comes in, that part is considered to be a character area, and masking calculations and density conversion are performed to improve the reproduction of characters.
Process by switching parameters such as UCR. Laser drive circuit 110 converts the digitally represented image signal into corresponding laser drive power.

FIG. 5 shows an overview of the entire apparatus. In the figure, 500 is a reader section, and 550 is a printer section. In the reader part, 501 is a document illumination lamp, 502 is a reflecting mirror, 503 is a lens, 504 is a line sensor,
505 is an image processing unit, and in the printer section, 551 is a laser, 552 is a polygon mirror, 553 is a developing unit, 554 is a photosensitive drum, 555 is a one-dimensional charger, 557 is a transfer belt, 558 is a paper feed tray, 55
9 is a pick-up roller, 560 is paper, 561 is a fixing roller, and 562 is a paper discharge tray. Original illumination lamp 5
The light reflected from the 01 original is guided by a reflecting mirror 502 to a lens 503 and is imaged on a line sensor 504. By moving the mirror unit relative to the original,
Scan the entire document. Image data converted into electrical signals by the line sensor 504 is processed by an image processing unit 505 and sent to the printer. On the printer side, this signal drives the laser 551 and converts the intensity of the laser beam. The laser beam is scanned by a polygon mirror 552, and the photosensitive drum 55 is charged in advance by a charger 555.
A latent image is formed on 4. This latent image is transferred to the developing unit 553.
The image is developed using toner of a predetermined color and transferred onto a sheet of paper fed onto a transfer belt. Paper 560 is prepared in the paper feed tray 558, and the paper 560 is prepared in the paper feed tray 558, and the paper 560 is
9, the sheets are fed one by one. The paper on which images are formed in four colors (cyan, magenta, yellow, and black) is heated by a fixing roller 561 to fix the toner.
The paper is ejected to a paper ejection tray 562.

FIG. 2 is a block diagram showing a more detailed configuration of the pre-image processing section 101. 200r, 200g, 20
0b is A/D converter, 201r, 201g, 201
b is a shading correction circuit, 202 is a masking correction circuit, and when an electric signal separated into three colors by a line sensor is input, each A/D converter 200r to 2
The intensity of the incident light is converted from an analog quantity to a digital quantity at 00b, and then the shading correction circuit 201r~
In step 200b, non-uniform sensitivity distribution is corrected. Subsequently, the masking correction circuit 202 corrects the spectral sensitivity of the line sensor, and the signal exits the pre-image processing unit as a standard RGB signal.

FIG. 3 is a block diagram showing a more detailed structure of the character determination area circuit 105. In the same figure, 300
is the minimum value detection circuit, 301 is the line memory, and 303 is the 5
×5 pixel average circuit, 304 is 3 × 3 pixel average circuit, 30
5. 306 is a binarization circuit, 307 is a halftone detection circuit, 30
8 is a reduction circuit, 309 is an enlargement circuit, and 310 is an O
This is an R circuit. From the input RGB signals, the minimum value detection circuit 300 selects the smallest signal, that is, the darkest color signal, and the line memory 301 delays it one line at a time. 5 for average circuits of 303 and 304 respectively.
Calculate the average value of ×5 pixels and 3×3 pixels. The binarization circuits 305 and 306 binarize the average value of 3 x 3 pixels and the unaveraged original signal, respectively, using the average of 5 x 5 pixels as reference data. The halftone dot detection circuit 307 examines the part printed with halftone dots in the document, and thins out the data using the reduction circuit 308 and the enlargement circuit 309, so that only the image area remains and outputs it as a character area signal.

The character area thus detected is then run-length encoded to compress the amount of data, and then stored in the area memory. Run-length encoding/decoding is a well-known method used in facsimile machines and the like, and when the same bit continues, it is expressed by replacing it with a representative code. For example 00000111000
A sequence of 12-bit data called 0, with 5 0s and 3 1s.
, encoded as four consecutive zeros. There are methods for performing one-dimensional encoding that processes each line, and methods for performing two-dimensional encoding that processes multiple lines at once, and either method may be used. If the latter method is adopted, the capacity of the area memory can be further reduced.

FIG. 4 is a block diagram showing a more detailed configuration of the cyan post-image processing section. In the same figure, 400r
~400b is a density conversion circuit, 401 is a minimum value detection circuit,
402 is a masking correction circuit, 403 is a selector, 40
4 is an edge enhancement circuit, 405 is a γ correction circuit, 406 is a selector, and 411 to 414 are registers. Image memory 1
The image signal read from 03 and decoded by the image decompression unit 104 becomes three color signals of R, G, and B and is input to the image processing unit.
b converts R, G, and B luminance data to C, M, and Y density data. Next, the minimum value detection circuit 401 finds the minimum value among C, M, and Y, and uses this as the K signal, and the next masking correction circuit 402 performs UCR and masking correction. Further, the γ correction circuit 404 corrects the positive gradation line in the printer portion to generate cyan print data. At this time, if a character area signal is input, selectors 403 and 406 operate to select registers in which parameters suitable for characters are set for masking matrix coefficients and edge enhancement coefficients.

Similar processing is performed for the remaining magenta, yellow, and black colors to generate data to be passed to the laser drive circuit. (Second Embodiment) FIG. 6 is a block diagram showing the structure of a second embodiment of a copying apparatus according to the present invention. In the same figure,
600 is a line sensor, 601 is a pre-image processing unit, 602
603 is a selector; 604 is an image compression unit; 605 is an image memory; 606 is an area register;
07 is an image decompression unit, 608 is a comparator, 609 is a post-image processing unit, 610 is a laser drive circuit, and 611 is a microcomputer. In order to perform character processing, it is first necessary to detect a character area and set it in the area register 606. For this purpose, first, a selector is set from the microcomputer 611 to import the result of character area detection into the image memory 605, and the document is prescanned. The image signal obtained by the line sensor 600 is subjected to analog-to-digital conversion, shading correction, and color correction in a pre-image processing section 601 to become an R, G, and B digital signal. A character area determination circuit 602 generates a signal representing a character area from this RGB signal. The area signals are stored in the image memory 605 via the selector 603. Next, the microcomputer 610 reads the contents of the image memory 605 and obtains the position of the character area. Then, coordinate values are set in the area register so as to include the character area. Subsequently, after switching the selector 603 to the image signal side, the document is scanned again, and data obtained by compressing the image signal is stored in the image memory. Next, the image data is read from the image memory and output. At this time, the comparator 608 compares the coordinate values representing the position of the image signal being read with the set character area, and determines whether the coordinates are included in the character area. It is determined whether or not it is possible, and the result is passed to the post-image processing unit 609. The image signal stored in the image memory 605 is read out and encoded by the image decompression circuit 607. The signal is then processed by the image processing unit 609. At this time, the image area is and character area processing.

There is a limit to the number of areas that can be set in the area register 606, but if the character areas exist at different intervals and exceed the number of areas that can be set in the area register, you can set a rectangular area that includes the area registers. good.

[0019]

[Effects of the Invention] As explained above, according to the present invention,
By focusing on a method suitable for character area signals, which are locally concentrated and exist, and encoding them differently from image signals, it is possible to efficiently store character areas in memory. Become.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a first embodiment of a copying apparatus according to the present invention.

FIG. 2 is a diagram showing the configuration of a pre-image processing section.

FIG. 3 is a diagram showing the configuration of a character area determination circuit.

FIG. 4 is a diagram showing the configuration of a post-image processing section for one color.

FIG. 5 is a diagram showing the overall configuration of a color copying apparatus according to the present invention.

FIG. 6 is a block diagram showing the configuration of a second embodiment of the copying apparatus according to the present invention.

[Explanation of symbols]

100 line sensor 101 pre-image processing unit 102 image compression unit 103 image memory 104 image decompression unit 105 character area determination circuit 106 run-length encoding circuit 107 area memory 108 run-length decoding circuit 109 post-image processing unit 110 laser drive circuit 200r, 200g, 200b A/D converter 2
01r, 201g, 201b Shading correction circuit 202 Masking correction circuit 300 Minimum value detection circuit 301 Line memory 302, 304 Average circuit 305, 306 Binarization circuit 307 Halftone detection circuit 308 Reduction circuit 309 Enlargement circuit 310 OR circuit 400r, 400g, 400b Density conversion circuit 401
Minimum value detection circuit 402 Masking correction circuit 403 Selector 404 Contour enhancement circuit 405 γ correction circuit 406 Selector 500 Reader section 501 Original illumination lamp 502 Reflection mirror 503 Lens 504 Line sensor 505 Image processing unit 550 Printer section 551 Laser 552 Polygon mirror 553 Developing unit 554 Photosensitive drum 555 Primary charger 557 Transfer belt 558 Paper feed tray 559 Pick up roller 560 Paper 561 Fixing roller 562 Paper discharge tray 600 Line sensor 601 Pre-image processing unit 602 Character area determination circuit 603 Selector 604 Image compression unit 605 Image memory 606 Area register 607 Image decompression unit 608 Comparator 609 Post-image processing unit 610 Laser drive circuit 611 Microcomputer

Claims (2)

[Claims] 1. A copying apparatus, comprising an input means for inputting image data, an encoding means for encoding the image data inputted by the input means, and a storage means for storing the image data encoded by the encoding means. a decoding means for decoding the image data stored in the storage means; an image processing means for processing the image data decoded by the decoding means by one of a plurality of image processing methods; A copying apparatus comprising: a determining means for determining the nature of an image based on image data inputted by an input means; and a changing means for changing the image processing method based on determination information of the determining means. 2. The changing means includes a determination information encoding means for encoding the determination information using an encoding method different from that of the encoding means, and a determination information encoding means for storing the determination information encoded by the determination information encoding means. The image processing method includes an information storage means and a determination information decoding means for decoding the determination information stored in the determination information storage means, and changes the image processing method based on the determination information decoded by the determination information decoding means. The copying apparatus according to claim 1, characterized in that: