JP2954234B2 - Color document image processing system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a system having a function of inputting, storing, and retrieving an image including color information such as a color document, and a function of outputting to a display or a printer. Regarding, efficient encoding of a mixture of monochrome images and color images,
Also, the present invention relates to an image processing system having a function of displaying a monochrome image at high speed in addition to color display at the time of search.

[Conventional technology]

2. Description of the Related Art Conventionally, when storing and communicating image information, data encoding is generally performed to suppress redundancy and reduce the amount of data.

On the other hand, in a device that handles a color image as digital data, the image is divided into three types of multi-valued data (hereinafter, each component is referred to as each component in the present specification). R, G, B are called, and the data of each color component is
R data, G data, and B data).

For example, in a color copying machine, the input R, G,
Output using the image data of B as it is. Also, when binarization processing is necessary, such as outputting to a printer, multi-valued RGB data is binarized and output independently for each color. As a well-known example which has enhanced the function of this method, there is, for example, JP-A-63-174472. This known example,
The figure shows a method in which luminance information is calculated from R, G, and B, and the binarization method is switched according to the value.

However, these three types of data have a high correlation between the three colors. In particular, since the R data, the G data, and the B data have the same value in the monochrome portion of the image, the redundancy is high and the coding efficiency is low. (Hereinafter, a monochrome portion of an image is referred to as a monochrome region.) Even in a color document, many portions in a text region are monochrome regions. In particular, there are many monochrome documents in which a red or blue seal is imprinted on a monochrome document or correction is performed using red characters. Most of these documents are composed of monochrome areas.

Therefore, the method that handles R, G, B multi-valued data as it is is inefficient for monochrome areas, so it is necessary to send an electronic file system that stores a large number of document image data or send document images at a low data transfer rate. It is not suitable for faxes with no information.

On the other hand, in a TV or a VTR, a method of converting RGB color image data into luminance information and two kinds of color difference information, performing an orthogonal transform, encoding the coefficients, and storing the same is widely used. ing. This method handles only luminance information in a monochrome area having no color difference information. Therefore, the coding efficiency is high for an image including many monochrome areas. Therefore, an example of using this method for a document is shown. (For example, Japanese Patent Application Laid-Open No. 63-9282, etc.) However, since this method mainly deals with natural images and the like, the following problems occur when handling document images requiring resolution.

(A) Since the density of a line graphic such as a character changes sharply, the coding efficiency is significantly reduced.

(B) When the compression efficiency by encoding is increased, lossy encoding is performed. Therefore, when data transfer is performed using raster image data as a medium such as a facsimile, the data changes sequentially every time the data is converted, that is, each time the data is transferred.

(C) Documents that handle documents as binary images, such as facsimile and electronic file systems, cannot be directly output.

(D) Data compatibility with the conventional monochrome system is lost.

[Problems to be Solved by the Invention] Generally used color documents often include a large monochrome area while including a color image in a part of the image. In particular, in monochrome documents with red seals, color information is meaningful only when it is colored.
Reproducing colors accurately is not important. It is inefficient to accumulate all R, G, B data for these images. Therefore, even if a system targets a document, even if a system targets a color image, high encoding efficiency is required for a monochrome image and a character.

However, as described above, conventional systems for handling color images target only color halftone images. For this reason, efficient handling of a document including a color image, a monochrome image, and a character or the like has not been considered.

For example, the method of using multi-valued R data, G data, and B data as they are requires all three types of data even for a monochrome area. On the other hand, a data encoding method using luminance / color difference conversion is originally designed for a device such as a TV that handles natural images. Therefore, it is suitable for an image having a gradual change in density, but is not suitable for a document image including many portions having a very large density change such as characters.

In addition, many of the facsimile and electronic file systems widely used so far have an input / output device for binary monochrome images. Therefore, color document imaging systems can also be used more widely if they are compatible with them. For that purpose, it is necessary to maintain compatibility in the data recording format. However, the conventional example does not consider this compatibility.

A first object of the present invention is to provide a color image processing apparatus that efficiently encodes and accumulates various types of document images regardless of whether they are color documents or monochrome documents. Above all,
Efficient storage is possible for images with a mixture of monochrome parts, which are common in color documents.
In particular, for color documents that require more efficient storage of data than color reproduction, such as a document with a red seal, mainly in a monochrome area, we will provide a color image processing device with higher encoding efficiency. is there.

Another object of the present invention is to provide a color image processing apparatus compatible with a conventional image processing apparatus for monochrome images.

Still another third object of the present invention is to provide an image processing apparatus capable of displaying the contents of each image at a high speed, for example, when searching for the contents of color image data stored in a large amount on an optical disk or the like. Is to do.

It is a fourth object of the present invention to provide a color image processing method for storing color image data in a format that maintains compatibility with conventionally stored monochrome image data.

[Means for Solving the Problems] In order to solve the above problems, the present invention has the following two features.

First, in the present invention, data of R, G, and B primary colors (R data, G data, and B data) of a color image are converted into two independent data.
It is to be treated as value image data. Accordingly, when outputting one color image, three binary images of the image, in which the R component, the G component, and the B component are respectively recorded, are input.
Each is output as R data, G data, B data,
It has a means to represent two color images. And furthermore,
There is provided a means for inputting one of R data, G data, and B data of the image, and expressing the monochrome image as luminance data.

In addition, in order to target a document image in which a color area and a monochrome area are mixed, binary attribute information that records whether each part of the image belongs to the color area or the monochrome area is also a binary image information. It also has means for recording data in the same format.

Hereinafter, in the present specification, the data of the three primary colors of a color image will be referred to as R data, G data, and B data, respectively.
When each of three pieces of binary image data used to represent one image is individually referred to as a plane.

Secondly, the following four types of data storage and processing modes are provided, means for switching between these modes according to external designation, and means for recording a mode identifier in image data to be stored. It is to have.

 Next, the mode will be described.

Mode (I) Monochrome mode: Only luminance data among image data is stored.

Mode (II) full color mode: R, G, B color image data is stored in R, G, B planes, respectively.

Mode (III) Multi-color mode: Each part of the image is converted to a monochrome area, a red area,
The image data is separated into blue regions, and each image data is stored in another plane.

Mode (IV) hybrid mode: a color area requiring more color information and a monochrome area in an image are identified, and only luminance data or data of one color of RGB is stored in the monochrome area. On the other hand, in the color area, R, G, B
The value data is stored in each plane.

Here, the mode (I) is used when a monochrome document is input, and handles only luminance information of an image. The luminance data is usually calculated from R data, G data, and B data by calculation. However, depending on the wavelength characteristics of an image input device such as a scanner to which the data is input, for example, G data can be used instead.

The mode (II) is a mode used for a color photograph or the like, in which binary data of R, G, and B are handled in the same manner as three monochrome binary images. The stored data is R
Data, G data, and B data.

The mode (III) is intended for a document which is often present in an office document or the like, and which has been stamped or corrected in red or blue on a monochrome document.

In these documents, it is important information that red and blue are "colored", and accurate color reproduction such as in color photographs is not generally required. Therefore, these images are handled in the form of monochrome image data, plus, and image data of a colored portion. Specifically, a method is used in which luminance data is recorded as G of the color image, and the image of the colored portion is assigned to “red” and “blue” and recorded as an R plane and a G plane. Thus, the color portion is quantized to either red or blue and stored. In this case, by expressing only the G data, a monochrome image can be output as in the mode (I).

The mode (IV) is for a document in which a monochrome document and a color photograph are mixed. In the mode (II) described above, an image is represented by three types of RGB data. Therefore, in the monochrome area in the image, the multi-value data of R, G, and B take the same value. Therefore, in the monochrome area, by storing only the luminance data, the redundancy can be further suppressed. Therefore, each part of the attribute (or a color region, black and white areas of the identifier, referred to hereafter as F _CM) of the image to be recorded.

The first object can be achieved by these means.

Further, in order to achieve the second object, means for binarizing each of the multi-valued data as an independent image,
Means for accumulating the second value data in a format similar to that of a conventional individual monochrome binary image is provided.

In order to achieve the third object, the present invention provides a means for recording data corresponding to a luminance signal as one of image data stored in the form of a binary image. It has means for reading out only image data corresponding to luminance information, and means for displaying the binary data of the read luminance signal as a monochrome pseudo halftone image.

Furthermore, R data present invention is inputted, G data, and B data, and binarized by the same processing method as an image processing apparatus for monochrome images of conventional binary, similar to the F _CM is also binary data recording I do. The fourth object is achieved by making this recording format the same as that of a conventional device that wants to maintain compatibility.

Further, when the R, G, B data is binarized, the use of the pseudo halftone processing causes a problem that the resolution of the line graphic portion is reduced and the color shift occurs in the monochrome portion.

Therefore, the present invention provides an adaptive binary conversion method for switching between pseudo halftone processing and simple binarization processing as image data binarization means.
Means for executing a binarization process, and furthermore, for a portion which does not require color reproduction by the pseudo halftone process as a result of the designated mode or color / monochrome discrimination,
There is provided a means for executing the adaptive binarization processing and performing a pseudo halftone processing on a color area where color reproduction is required. In addition, even in the mode (II), there is provided a means for preventing color shift by increasing the values of binary R data, G data, and B data for a monochrome area.

[Action]

The operation of each unit in the above-mentioned problem solving means will be described.

First, when dealing with a monochrome image, the point that the coding efficiency is reduced is that R,
This problem can be solved by storing all color information of G and B, and storing only luminance information in the case of a monochrome part or a document specified as a monochrome image from the beginning. Also, if you do not need accurate color reproduction, such as a document with a red seal,
In addition to accumulating the luminance information, the color information is accumulated after allocating only the color portion to a specific color such as red and blue, thereby further improving the efficiency.

In this case, since it is not necessary to reproduce colors, 2
There is no need to use pseudo halftone processing at the time of value conversion.
Even in the case of the binarization processing method, the processing that requires a line figure can be performed, so that the image quality of characters can be prevented from deteriorating.

Further, for a document in which most of the image is a monochrome area, by storing the color / monochrome identification information F, the redundancy of the data in the monochrome portion can be suppressed, and the encoding efficiency can be further improved. . This mode is particularly effective when a large number of documents are continuously input using an automatic paper feeder or the like. When a color photograph is included in some pages of the input document, in mode (II), the entire document is recorded with three pieces of RGB data. You need three times.

On the other hand, in mode (IV), most documents store only luminance information and all attribute identifiers F indicate monochrome, so that efficient recording can be realized.

The image data is binarized and stored by pseudo halftone processing or the like, so that MH (Modified Huffman) and MR (Modified Rea) are stored in the same manner as in a conventional apparatus for monochrome binary images.
d) and the like. Therefore, for example, a recording medium such as an optical disk can maintain compatibility with a conventional monochrome system.

Further, when the luminance information is binarized, a monochrome 2
A value image is obtained. Therefore, by using only the luminance information, it is possible to output with a conventional monochrome system.

In addition, in these binary image coding methods, there is no problem when the coding efficiency is sharply reduced in a line figure such as a character.

Furthermore, in these binary image data encoding methods,
The data amount of a portion where 0s or 1s continue can be minimized.
Accordingly, information such as color / monochrome identification information in which a value change is in units of regions has extremely high coding efficiency.

When a color image is represented by binary information, it is necessary to perform pseudo halftone processing to reproduce not only density but also color. However, when the pseudo halftone processing is applied to a line figure such as a character, the resolution of an image is reduced. Therefore,
For a portion that does not require color reproduction, such as a monochrome portion of a mixed document or a multi-color document, it is finely recorded as a line figure by an adaptive binarization process. On the other hand, in the color area, pseudo halftone processing is performed even for a line figure in order to reproduce a color. The switching of the two systems is the use of the color / monochrome identifier F _CM.

When an image is displayed by superimposing three pieces of binary data R data, G data, and B data, a color that originally does not exist may appear due to a difference in values between the three data. This is hereinafter referred to as color noise.

In the present invention, the color noises are particularly the modes (II) and (I).
V). In order to prevent this color noise, it is necessary that the data of the three planes have the same value.

Here, in the case of mode (II), the present invention
This problem is solved by having means for recording the same value on the three planes of R, G, and B when the monochrome area is determined to be a monochrome area.

〔Example〕

 One embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an example of the basic configuration of the present invention. In the figure, reference numeral 10 denotes a document or the like optically read by a known means, and each of R, G, B
Image input units for outputting multi-valued digital data of bits, buffer memories 11, 12, and 13 for temporarily storing input image data, and data correction units for correcting the values of multi-valued image data for 21, 22, and 23 Reference numeral 50 denotes a command input unit such as a keyboard for inputting an instruction from the user to the system. 70 denotes a control unit that controls the operation of the entire system. 100 denotes a color area or a monochrome area for each part of the input image. or it is determined, and outputs the color / monochrome identifier F _CM color /
The monochrome determination unit 200 identifies a line figure area such as a character in an image and an area to be binarized by pseudo halftone processing such as a photograph from an input R, G, B multi-value luminance data. The character / photo identification unit 250 is a color identification unit that determines in advance whether the color displayed by each pixel in the color area belongs to a specific color, such as red and blue. 300,310,32
0 is a binarization processing unit for binarizing input multi-valued data for each of R, G, and B planes, and 400 is an R, G, or B output based on a preset mode or the output of the color / monochrome determination unit 100. , binary image data and the input data selector selects and outputs an identifier F _CM of binary B, memory 510-590 is for storing binary data, 600 denotes a data bus, 610 and 615 various types of data on the bus Selector to select one of the 620
630 is an image processing unit that performs various data conversion for the first time by performing encoding and decoding processing on binary data by a known means.
Is a data storage controller for inputting and outputting coded data and directory information to and from a large-capacity data storage device such as an optical disk; 635 is a large-capacity data storage unit such as an optical disk;
Is a mode detection unit that reads the type and mode of the data from the directory information when reading image data from the disk, and outputs a mode signal that controls the operation of the system. 650 is a communication terminal that transfers encoded image data. , 700 is an output data selector for selecting and outputting various data on the bus based on the output of the mode detection unit 640, and 800 is for converting the R, G, B binary data sent from the output gate to the image display unit. Image display conversion unit to transfer, 820 is multi-valued R, G, B
An image display unit such as a color CRT that displays image data in the format of R, G, and B sent from the output data selector.
A color image print display unit 870 that converts the value data and transfers the value data to the image print unit 870 is a color image print device such as a color printer that prints the output from the image print conversion unit 850.

First, the flow of image data will be described. The image data is input from the image input unit 10 as 8-bit multi-value data for each of RGB. Hereinafter, in the present embodiment, the input multi-valued R, G, and B data are referred to as R ₁ , G ₁ , and B ₁ , respectively.

Now, consider a case in which R _I1 , G _I1 , and B _I1 are sequentially input from the image input unit 10 for each scanning line. Input images are temporarily stored in buffer memories 11, 12, and 13.

When the color / monochrome determination is performed, the multi-value data of the same pixel requires R, G, and B, respectively. Therefore, in the present embodiment, the memories 11 and 12 have a capacity capable of storing at least one scan line or more of data. is necessary. Therefore, the image input unit 1
0. In the case of a device that scans a document three times and outputs R, G, B data one screen at a time, the memories 21 and 22 must have a capacity to store at least one screen of data. . When R, G, and B data are repeatedly output for each pixel, the memories 11, 12, and 13 need only have the capacity necessary to match the timing of each unit. Also, from the image input unit 10,
The same applies to the case where R, G, and B are simultaneously input using 24 signal lines.

The input R _I1 , G _I1 , and B _I1 are first input to the image data correction unit 11,
After the effects of the wavelength characteristics of the input device are corrected in 12, 13, the image data is binarized by the binarization processing units 300, 310, and 320. Here, the corrected data is R _I2 , G _I2 , and B _I2 , respectively. In the following, in the present embodiment, in the case of binary data, "'" is added to the conversion. Therefore, for example, 2 of multi-value data R _I2
The data after the conversion is denoted as R _I2 '.

The internal configuration and operation of the binarization processing units 300 to 320 will be described later in detail, but have means capable of executing a plurality of types of binarization methods, for example, simple binarization processing and pseudo halftone processing, It has a function to switch according to external instructions.

As a result of the binarization processing, the multi-valued color image data is converted into three types of binary data R _I2 ′, G _I2 ′, and B _I2 ′. In this embodiment, the luminance data is substituted with the G data. Therefore, the binary image data G _I2 ′ can be treated as a monochrome binary image.

On the other hand, R _I1 , G _I1 , and B _I1 are also input to the color / monochrome determination section 100. The color / monochrome determination unit outputs a binary color / monochrome identifier F by a known method in units of a fixed number of pixels. In the present specification, the determination is performed for each pixel, and “1” is output for a color area and “0” is output for a monochrome area.

The determination result F _CM ′ is input to the above-described binarization processing 200 to 220 and the data selector 400.

On the other hand, the character / photo identification unit 200 uses a known method.
Multi-valued image data is input, and a binary region identifier F _CP 'is output in units of a fixed number of pixels. In the present specification, the determination is performed on a pixel-by-pixel basis, and “1” is output for a photographic area and “0” is output for a character area. The region identifier F _CP ′ is input as a control signal to the above-described binarization processing units 200 to 220.

The data selector 400 receives the input 4 based on the mode set from the outside and the color / monochrome identifier F ′.
Logical operation is performed on the binary data R ', G', B ', F'
It outputs binary outputs R _S ′, G _S ′, B _S ′, and F _CMS ′. The operation of the data selector 400 will be described in detail later,
For example, in mode (I), only G _S ′ is output and R _S ′
B _S ′ Fs _S ′ performs processing such as always outputting only “0”.

The four types of binary data output from the data selector 400 are passed through the data bus 600 to the image data memory 5 respectively.
It is accumulated at 10,520,530,540. Each memory stores one type of binary data for one image. In the present specification, each of the image memories is hereinafter referred to as a plane. Also, these memories can actually exist on a single memory board.

The selector 610 selects one of the planes in the image memories 510 to 580 and connects it to the image processing unit 620. Note that the image processing unit 620 also has a code decoding function.

For example, when an image is stored on an optical disk or the like or transferred using a line such as a facsimile, data obtained by encoding these four binary values is used. Specifically, image memories 510-5
Selects the four types of binary image data existing in 80
At 610, the images are selected one by one and input to the image processing unit 620. The image processing unit 620 encodes the input binary image data one by one according to a known method such as MH, MR, or MMR, for example.
Transfer to an appropriate plane in the image memories 510 to 580. The code data stored in the memory is sent to the selector 615,
Data is selected one by one and sequentially stored in the data storage controller 630.
Is forwarded to The data storage control unit 630 stores each data and directory information corresponding to the data in the optical disk 650.
To accumulate. As a result, the code data recorded on the optical disk has the same format as the monochrome binary image data.

Here, the attribute of each data, the input mode, and the like are recorded as directory information. In the case of the mode (IV), a binary color / monochrome identifier is used similarly to the image data.
F _CMS ′ is also recorded as encoded binary image data.

With the above method, three multi-valued image data, R ₁ , G ₁ , B
₁ in the same format as multiple monochrome binary image data,
It can be encoded and stored.

On the other hand, in the case of reading out the code data stored in an optical disk or the like and outputting a color image, the following procedure is taken. One color image is recorded on the optical disk 650 as up to four pieces of binary image data encoded by the above-described method. Therefore, these data are read out one by one by the data storage control unit 630, and are temporarily stored in the image memory 2 and decoded by the image processing unit 620 to be decoded into three types of binary image data and color / monochrome identifiers. F
_{The CM} is obtained and stored again in the memories 510, 520, 530, 540 for each plane. At this time, the directory information is read by the data storage control unit 620 before reading the image data. The data accumulation control unit 630 detects which of the data R _S ′, G _S ′, B _S ′, and F _CMS ′ the data corresponds to based on the directory information, and controls the selector 615 according to the result. The resulting read image data is written to an appropriate memory. On the other hand, the data storage control unit 630
Extracts the input mode of the image from the directory, and controls the output data selector 700 based on the result. The configuration and operation of the output data selector 700 will be described later in detail similarly to the input data selector 300. For example, when an image is displayed on the color CRT 820, in the mode (I), the value of G _S ′ corresponding to the luminance data is set to R, Output as G and B values respectively.

In the above-described manner, binary image data R _S ′, G _S ′, and B _S ′ are obtained from the accumulated code data. Therefore, a means for displaying and outputting this image data will be described next.

First, when the color display device 820 has a function of displaying only a binary color image, the image memories 510, 520, 530
The above three types of binary data R _S 'and G _S ' B _S 'are displayed as they are.

On the other hand, when the color display device 820 supports a full-color image, each of the RGB is converted into multi-valued RGB data by the image display conversion unit 800, transferred to the color CRT 820, and output.

Here, the principle of the process of obtaining multi-value data from the stored binary image data is as follows.

Normally, when a human looks at a pseudo halftone image, the density of a certain point on the pseudo halftone image is perceived by the distribution of black pixels in the vicinity thereof. Therefore, in the case of binary image data obtained by performing pseudo halftone processing on multi-valued image data, by using the distribution state of the binary data, multi-valued image data equivalent to the original image can be detected by the human eye. Can be obtained.

Specifically, the density of each pixel can be determined by scanning the original image through a scanning window of a specific size and detecting the distribution state of black pixels in the vicinity of each pixel.

According to the above principle, color image data input in multi-valued RGB three primary colors can be stored as three pieces of binary image data, converted into multi-valued data and output again.

In this embodiment, a display for displaying an image composed of multi-valued RGB data is hereinafter referred to as a "full color CRT", and a display for displaying an image represented by binary RGB data is referred to as a "color CRT".

For printer output, output data gate 700
After the three types of binary data R _S ′, G _S ′, and B _S output from the printer are converted into a data format suitable for the output device connected to the system by the image print conversion unit 850, the color LBP (Laser Bea
m Printer) to a color image printing unit 870.

On the other hand, when searching for a large number of images, it is required to display the contents of each image at high speed. In the present invention, the image data G _S ′ whose luminance information has been binarized has already been stored in the optical disk. The image data G _S ′ is an image that represents the original image as a monochrome pseudo halftone image.

Therefore, when displaying an image on the optical disk 650 at high speed, only the luminance information G _S ′ is first read out of the four types of code data, and is decoded and then input to the output data selector 700.

The output data selector 700 converts _GS ′ into an image display conversion unit 800
As binary data R _S ′, G _S ′, and B _S ′.

As a result, when one plane of the signals of three planes necessary for forming a color image is input,
A monochrome image can be displayed on the color CRT820.

Further, in a system for monochrome images, since this processing is performed unconditionally, the luminance data G _S ′ can be displayed / output as a monochrome image.

Next, an example of the internal configuration of each unit described above will be described in detail.

First, the image data correction units 11, 12, and 13 will be described. The image data correction units 11, 12, and 13 convert the multi-valued color image data R _I1 , G _I1 and B _I1 input from the image input device 10, and convert the multi-valued color image data R _I2 , G _I2 and B _Has the function of outputting _I2 . Generally, multi-valued image data output from an image input device is greatly affected by the wavelength characteristics of the input device, and the purpose is to correct this. In particular,
It can be realized by three ROMs or a RAM (Random Access Memory). When a RAM is used, data can be created sequentially by external designation. in this case,
The density and color tone of the image can be arbitrarily changed.

In this embodiment, outputs from the image data correction units 11, 12, and 13 are treated as color image data.

Next, the color / monochrome identification unit 100 will be described.
Color / monochrome identifying unit 100 is more multi-value color image data _{R I2, G I2, B I2} , for each pixel or certain region unit, and outputs a binary color / monochrome identifier F _CM '.

In the present invention, the purpose of the identification unit is the following three points.

(1) In the case of the mode (IV), the redundancy of data in the monochrome area is suppressed.

(2) In modes (II) and (IV), the values of R _I2 ′ and G _I2 ′ B _I2 ′ are made equal for a line figure expressed in monochrome. (A pixel having a difference between R _I2 ′, G _I2 ′, and B _I2 ′ will output a color other than white or black.) (3) In mode (III), the quantum is changed to red and blue. Extract the part to be converted.

As specific identification means, a number of methods are already known, and these methods can be applied. In the present invention, since the purpose of color / monochrome identification is as described above, the white area may be determined in any manner. Accordingly, for example, when a character is considered as a text region including a surrounding white background, the color region and the monochrome region generally have a fixed area. Further, in an actual device, there may be a case where RGB signals input as data of one pixel read from the image input device are not strictly at the same position. In this case, the pixel on the white / black boundary is
Since the values between RGB are different, it may be regarded as a color area.

In consideration of storing the color / monochrome identifier in the mode (IV), the identifier can be output in units of, for example, an area of about 8 × 8 pixels.

Next, the character / photo region determination unit 200 will be described.
The purpose of the determination unit is to select the optimal 2 according to the target image.
Is to carry out a valuation process. Therefore, the output F _CP 'of the determination unit is sent to three binarization processing units 300, 310, and 320. In addition, the result of this determination is that three types of color image data R,
When there is a difference between G and B, the image obtained as a result of the binarization process is degraded. Therefore, the character / photo area determination unit
Reference numeral 200 executes determination on single data such as luminance information. In this embodiment, since the G data is used as the luminance data, only the multi-value data G _I2 is input.

Therefore, the character / photo region determination unit 200 needs to have a function of executing a determination by real-time processing and outputting a binary region determination result while inputting multi-valued luminance data in pixel units. is there. The specific method to determine the text / photo area is:
There are already a number of known examples, of which Japanese Patent Application Laid-Open No. 63-316566 is an example satisfying the above conditions.

Next, the color identification unit 250 will be described. The color identification unit 250
When the mode (II) is set, it has a function of determining whether a color displayed by each pixel in the color area belongs to a specific color such as red and blue. FIG. 2 shows an example of a configuration diagram in a case where red or blue is assigned as an example. In the figure, 261 and 262 are differentiators for detecting a difference between two types of multi-valued data, 271, 272 and 273 are comparators, and 280 is an OR gate for outputting a logical sum. Here, the comparator 271 is composed of R _I2 and B _I2
And outputs binary data F _RB2 under the following conditions.

if R _I2 ≧ B _I2 then F _RBL = 1 R _I2 <B _I2 then F _RBL = 0 This binary data F _RBL is an identifier indicating that the color displayed by each pixel belongs to either red or blue. In this case, "1" indicates that the color is red, and "0" indicates that the color is close to blue.

On the other hand, the differentiators 261 and 262 are respectively R _I2 and G _I2 , and B _I2 and G _I2
And outputs the difference D _RG and D _BG of. The D _RG and D _BG are respectively determined by comparators 186 and 187 at a predetermined threshold T _CR.
And, it is compared to T _CB. The comparator 271, 272, and 273 binary data F _RH under the following conditions, and outputs the F _BH.

if D _RG ≧ T _CR then F _RH = 1 D _RG <T _CR then F _RH = 0 if D _BG ≧ T _CB then F _BH = 1 D _BG <T _CB then F _BH = 0 The logical sum F _RBH of these two types of binary data is _obtained .

This OR F _RBH is an identifier indicating whether to display red or blue or white or black for each pixel. By the case this identifier F _RBH is go-between, it can substitute even color / monochrome identifier F _CM Niyotsu output from the color / monochrome identification section 100. In this case, the portion within the dotted line 290 in the figure is unnecessary. However, in a document targeted for mode (II), the boundary between a monochrome portion and a color portion is often unclear. For example, when a red seal is made on a black character, it is necessary to switch the attribute for each pixel. Therefore, when the output of the color / monochrome determination unit 100 is, for example, in units of 8 × 8 pixels, the mode (I
It is effective to use this mechanism so that it operates only when I) is set.

Next, the three binarization processing units 300 to 320 shown in FIG.
Is described below. In the present embodiment, all three have the same configuration.

Various conventional binarization processing methods can be applied to the binarization. Therefore, by incorporating a plurality of processing methods and selecting an appropriate method based on an external mode designation or a color / monochrome determination result F ', optimization is performed according to the characteristics of the target image or output device. Can be. Figure 3 shows
FIG. 2 is a diagram illustrating a configuration example of a binarization processing unit 300 used in the present system. In this example, there are three types of binarization schemes: pseudo halftone processing using a tissue appropriate dither method, pseudo halftone processing using a minimum average error method, and binarization processing using a fixed threshold. 5 shows an example of a configuration when one is selected. In the figure, the multi-value data R _I2 , 33
Signals indicating the pseudo halftone processing method from the control unit 70 are input from 1 and 332, and the lower bits of the addresses in the main scanning direction and the sub-scanning direction of the output image are input from 341 and 342, respectively. The multivalued image data Y ₁ (x, y) is input from the image data correction unit 21100 to the adder 330 via the signal line 301. The adder 330 adds Y ₁ (x, y) and the error data E (x, y) input from the selector 335, and outputs multi-value data F (x, y). Here, the error data E (x, y) is
Normally, it is 0, and the value input from the signal line 399 is used only when the average error minimum method is used as the binarization method. Therefore, the selector 335 outputs 0 unless the average error minimum method is instructed as the processing method from the signal line 331.
The multi-valued data F (x, y) is sent through a signal line 339 to a comparator 340.
And compared with a threshold T. Based on the result of this comparison, the binary image data Y ′ ₃ (x, y) is determined. Here, the threshold value T is also selected by the selector 345 by a binarization method. The selection is performed according to an instruction input from outside via the signal line 332. In the case of the tissue-adaptive dither method, the threshold value fluctuates appropriately in accordance with the position of the output pixel. In this case, for example, the lower bits of the addresses of the output image in the main scanning direction and the sub-scanning direction are input to a ROM (Read Only Memory) 347 from the signal lines 341 and 342, and the output is used as a threshold value. A matrix of threshold values is entered in the ROM 347. In the case of a fixed threshold value, the register 344
Selects the output fixed value.

In the case of the minimum average error method, it is necessary to calculate error data E (x, y) for binarization processing. The error data E (x, y) is obtained by adding a predetermined weighting coefficient δ (to the error ε generated when the multivalued data F near the binarized (x, y) is binarized. m, n). FIG. 4 shows an example of the weight coefficient δ (m, n). * In the figure
The pixel to be binarized at that time, the coordinates (x,
It corresponds to the pixel of y).

Next, the operation of each unit will be described. When the weight coefficient is as shown in FIG. 4, E (x, y) is obtained by the following equation.

E (x, y) = 1/8 [ε (x−1, y−1) + ε (x + 1, y +
1) + ε (x−2, y) + ε (x, y−2) +2 {ε (x, y−1) + ε (x−1, y)}] On the other hand, the error ε of each pixel is multi-valued data. Either the difference between F and 0 or the difference between F and the maximum possible value Fmax of F. This value is obtained as follows. At some point, the comparator 340 sets the multi-valued data F (x ₂ −) of the coordinates (x ₂ −1, y ₂ ).
1, (y ₂ ) is binarized, F (x ₂ -1, y ₂ ) is calculated by the comparator 340
Are input to the differentiator 350 and the selector 355. Differentiator
355 is the maximum possible value of the converted image data F (x, y)
The difference between Fmax and F (x ₂ -1, y ₂ ) is output and sent to selector 355. For example, when S ₂ (x, y) takes a value from 0 to 255, Fmax = 255, and the differentiator 350 outputs 255−S ₂ (x ₂ −1, y ₂ ). Also, here, if F (x ₂ -1, y ₂ )> Fmax, the differentiator 350 outputs 0. Selector 350
Is F (x ₂ −1, y ₂ ) or Fmax−F according to the following conditions:
(X ₂ -1, y ₂ ) is output as an error ε (x ₁ -1, y ₁ ).

ε (x, y) = F (x, y): Q (x, y) = 0 Fmax−F (x, y): Q (x, y) = 1 Output ε (x ₂ −1, y ₂ ) is sent to a line memory 370 through a signal line 359. The process of obtaining E (x, y) from the error ε is executed by the latches 361, 375, 378 and the shift registers 360, 377. Next, the operation of each part will be described with reference to an example in which Q (x, y) is obtained. Binary data Q (x
When (−1, y) is determined by the 2ε processing unit, the latch 361,3
From the 75,378 and the line memories 370,380, the error ε
(X−1, y), ε (x−2, y), ε (x, y−1), ε (x
−1, y−1), ε (x + 1, y−1), and ε (x, y−2) are output. Here, the output data ε (x−1, y) and ε (x, y−1) of the selector 350 and the latch 378 are
Input to 360,377, 2 * ε (x−1, y) and 2 * ε
(X, y-1) is output. The adder 390 adds the six types of input multi-value data to calculate 8 * E (x, y) and sends it to the shift register 395. The shift register 395 obtains E (x, y) by shifting the input multi-value data. The obtained E (x, y) is supplied to the selector 335 by the signal line 399.
Is input to Here, the selector 335 outputs E (x, y) or 0 to the adder 330 according to the data E flag sent from the signal line 331 from the outside. If the output of the selector 335 is E (x, y), the final output Q is a pseudo halftone image. On the other hand, if the output of the selector 335 is 0, the final output Q
Is a simple binarized image with a fixed threshold.

When x = 1 or y = 1, a part of ε required to obtain E (x, y) may not exist. In this case, for example, the line buffers 350 and 3
E (x, y) is determined using the value recorded in 55.

Next, a description will be given of a method of selecting a ternarization method executed by the binarization processing unit. The selection is performed in the following two steps. First,
Next, selection is made between simple binarization processing using a fixed threshold value and pseudo halftone processing. Next, in the case of pseudo halftone processing, a specific processing method is determined.

First, the decision between the first simple binarization processing and the pseudo halftone processing is made based on the set operation mode and two kinds of identifiers F _CM '.
It is determined by F _CP ′. FIG. 5 shows the conditions and selection results.

In the present embodiment, two types of pseudo halftone processing methods, the systematic dither method and the minimum average error method, can be executed. This 2
The method is set in advance according to the target image or the user's preference. The setting is performed by the mode setting unit 50 in FIG.
For example, in the case of a monochrome dot image, the image quality is degraded when the systematic dither method is used. This is because moire occurs due to interference between the cycle of the halftone dots of the original image and the cycle of the dither matrix of the binarization processing. This problem can be solved by performing a binarization process using a method having no periodicity such as the average error minimum method when the current image is a halftone image.

Therefore, by including one kind of pseudo halftone processing method having no periodicity such as the average error minimization method as a binarization method of the image input device connected to the system, the selection of the processing method can be further facilitated. Can be expanded.

With the above configuration, the multi-valued color image data R _I2 , G _I2 , B
_{From I2} , three types of binary image data R _I2 ', G _I2 ', B _I2 'are calculated and transferred to the data selector 300.

Next, the data selector 300 will be described in detail. The data selector 300 inputs four types of binary data R _I2 ′, G _I2 ′, B _I2 ′, and F _I2 according to the set mode F _MD signal and the identifiers F _CM ′, F _TP ′, and F _RB. ′, Four types of binary data R _S ′, G _S ′, B _S ′, and F _S ′ are determined and output.

 The operating conditions are as shown in FIG.

For example, in the mode (I), only G _I2 ′ is output as G _S ′, and R _S ′, B _S ′, and F _S ′ are always “0”. In the mode (II), any one of R _S ′, G _S ′, and B _S ′ is output, and the other operation is always set to “0”.

The four types of binary data output from the data selector 300 are stored as binary image data in the image memories 510, 520, 530, and 540, respectively. Image memory 510-580
Actually, it can be realized by one memory board. The capacity needs to be equal to or more than one binary image data of the target document image for each plane. Also, as a whole, four 2
In order to accumulate value image data and efficiently execute image processing to be described later, a capacity of eight planes or more is required. For example, when inputting A4 size document with 16 lines per 1mm resolution, each plane is more than 2MB (2MB), 16M in total
B or more capacity is required.

Next, when this image data is stored on an optical disk or the like, it can be handled in the same way as storing four monochrome binary images. The selector 610 selects one of the data buses 600.
Books are sequentially selected and four types of binary image data are transferred to the image processing unit 620 one by one. The image processing unit 620 executes encoding of the binary image data by a known means such as MH encoding or MMR encoding. The encoded data is written to the optical disk 635 through the data accumulation control unit 630. Also, by connecting to the communication terminal 650, the code data can be transferred to the outside. Since this communication terminal can be used as long as it can handle binary image code data, for example, a fax or the like can also be connected. In a general device using an MH code or an MMR code, when 0 continues on a scanning line,
The data amount after encoding can be minimized. Therefore, the monochrome part in the input image is represented by R _S ′, B _S ′
And F _CMS ′ are always “0”, so that the data amount after encoding can be minimized. Therefore, even when an image in which a color image and a monochrome image are mixed is handled, an increase in the data amount of the monochrome portion can be minimized, and high coding efficiency can be obtained.

Next, a recording format and a directory configuration when data is accumulated on an optical disk will be described. FIG. 6 shows an example of a recording format on an optical disk. Rectangle 911 in Fig. 6
Reference numerals 914 to 914 denote portions for writing directories for one binary image, and rectangles 921 to 924 each denote portions for writing binary image data for one binary image.

In the case of the present embodiment, one piece of color image data
It is recorded on the optical disk as value image data.
In this case, the directory of the image data is also recorded on the four-spectrum disc. Here, for both image data and directory, G _S ′ for luminance data is described at the top, and R _S ′, B _S ′,
The F _CMS 'data follows.

FIG. 7 shows a part of the structure in the directory 911. This configuration is the same for 912 to 915. In the drawing, 931 is a unique number as a binary image, that is, a binary image ID added to each plane, 932 is a pointer indicating the position of the next plane, 933 is an image ID which is a unique number of each color image itself, 9
34 is a next image pointer indicating the image data position of the next document,
Reference numeral 935 denotes a mode identification set at the time of image input, and reference numeral 936 denotes a column for entering a plane name identifier indicating one of the data R _S ′, G _S ′, B _S ′, and F _SCM ′.

Next, a process of displaying an image recorded on the optical disk will be described.

First, the case of outputting a color image will be described. Data reading is performed in the following procedure. First, in response to a search execution instruction, the optical disk 650 outputs four pieces of binary data whose color image unique number matches the specified image.
R _S ′, G _S ′, B _S ′, and F _SCM ′ are sequentially read. The reading is
This is executed by the image data accumulation control unit 650 together with a directory corresponding to the image data. Here, the directory information is sent to the mode detection unit 640. The mode detector 640 extracts the contents of the mode identifier in the entry column 935 from the directory information of each plane, and outputs
Output to The output data selector 700 will be described later in detail. Also, in the mode detection unit 640,
The plane identifier in the entry column 936 is also detected and output to the selector 615. The four binary image data R _S ′, G _S ′, B _S ′, and F _SCM ′ that are successively read by the selector 615 are written to the image memories assigned to the respective planes.

On the other hand, when the image to be displayed is a monochrome image, the mode detection unit 640 extracts the mode identifier, so that only the luminance information of the image is recorded.

It can be detected that the image is a monochrome image. In this case, only the binary image data G _S ′ indicating the luminance is read.

Also, when displaying the contents of each image in a short time,
From the four stored binary image data, only G _S 'is read out, decoded and output as a monochrome image. In this case, according to an instruction from the command input unit 50, of the image data to be searched, the plane identifier in the directory information sequentially reads only the image data of G _S ′, and the corresponding image data in the image memories 510 to 580 is read. Write to the plane you want.

With the above configuration, it is possible to realize an image processing apparatus having a function of efficiently storing color image data and displaying a monochrome image at high speed in addition to color display at the time of output.

Next, compatibility with a device for a monochrome binary image will be described. For example, an electronic file device and the like conventionally target a monochrome binary image. With these devices, the input was accumulated. A case where an image is output by the present apparatus will be described. Image data input by a conventional device that handles monochrome images is a binary image of luminance information. As described above, the present invention has means for directly outputting a binary image of luminance information accumulated on an optical disk or the like. Therefore, an image input by a conventional monochrome image apparatus can be output by the following method.

An example of the internal configuration of the directory 911 in this case is shown in FIG.
Shown in the figure. This figure shows the directory of the binary image data for the luminance signal as in FIG. 6, but the directory of the image data for the color difference signal is the same as in FIG. Here, a binary image ID entry column 931 as a binary image, a next page pointer 932 indicating the position of the next binary image, and a portion where each item as a binary monochrome image is entered are a conventional monochrome image. Use the same format as the directory configuration in the device. As a result, the image data written by the conventional monochrome device can be output by the device of the present invention as a monochrome image.

On the other hand, when data is entered by the present apparatus, in addition to the above items, a unique number of an image ID assigned to each color image is entered in the entry column 933, and a pointer address indicating the next luminance data position is entered in 934. . Note that even if the input image is a monochrome image, the image ID is newly given, and the pointer address of the next image data is entered in 934. Further, a mode identifier indicating monochrome mode input is recorded in the entry column 935, and a plane identifier indicating that the plane is luminance data is recorded in 936. As a result, the image data recorded on the optical disk by the device described in the present invention is
Even a conventional monochrome device can search and output.

Next, a portion for outputting an image recorded on the memory will be described. It is recorded on the memory. Data is,
The same applies to the case where the input is made via the input data selector 300 from the image input unit 10 and the case where the input is made from an optical disk. The only difference is the input path of the item that determines the operation of the output data selector 700.

First, a binary color image on the memory is converted to a full color CR.
The case of displaying on T820 will be described. Image memory 510
The binary image data R _S ′, G _S ′, B _S ′ and the color / monochrome identifier F _CM ′ on 540 are displayed according to the display instruction.
The data is transferred to the output data selector 700.

Here the output data selector 700, a color / monochrome identifier F _CM ', mode identifier F _MD or mode detector 64,
The output mode signal from 0 causes the input data selector 300
Similarly, the input color image data R _S ′, G _S ′, B _S ′
The three types of output color image data R _O ′, G _O ′, and B _O ′ are determined and output.

The operating conditions are as shown in FIGS. FIG. 8 shows a case where data input from the image input unit 10 is displayed, and FIG. 9 shows a case where data read from an optical disk is displayed. Output data selector 700
Plays the role of G _S ′ as R _O ′, G _O ′, and B _O ′ in a monochrome image.
Is output, and in other cases, R _S ′, G _S ′, and B _S ′ are output. The output three types of binary image data are converted into three types of multivalued image data R _O , G _O , and B _O by the display halftone conversion unit 820 and output to the bit map memory of the color CRT 820. . The operating principle of the display halftone converter 800 will be described later in detail.

On the other hand, when displaying an image at high speed, for example, when examining the contents of image data stored on an optical disk or the like, the output data selector 700 is set to the same state as that for displaying a monochrome image. In this case, a monochrome image can be displayed only with the binary data G _S ′ corresponding to the luminance data. Therefore, by reading only G _S ′ of each color image from the optical disk, a monochrome image can be output on the color CRT 820 simply by reading one of the four binary data. In this case, a display speed similar to that of outputting a monochrome binary image can be obtained.

Also, as an output destination of the output data selector 700, a color image display unit and a monochrome image display device are connected, and if the selector also selects a data output destination, a monochrome output is instructed when monochrome output is instructed. When output to an image device, any function can be realized.

Further, for example, the data reading method is changed according to the output device connected to the system. In other words, when a monochrome image output device is connected, it is always possible to read out only the luminance information. In this case, this can be realized by inputting the device identifier assigned to each connected device to the output data selector 700.

Here, the case where three types of color image data R _O ′, G _O ′, and B _O ′ are output in parallel from the output data selector 700 has been described. If each plane is to be output in chronological order due to restrictions on the output destination, etc., one plane is sequentially output from the input three-plane binary image data R _O ′, G _O ′, and B _O ′. I do. In this case, except that each data is input to the output data selector 700 three times, it is the same as the case of the parallel output described above.

Next, the operation principle of the display halftone conversion unit 800 will be described. The display halftone converter 800 has a function of inputting one-plane binary image data and outputting one-plane multi-value image data. A specific configuration will be described below.

First, the principle of processing for restoring multi-valued image data from binary image data will be described. When a human looks at a pseudo halftone image, the density of a certain point on the pseudo halftone image is felt by the distribution state of the approximate black pixels. Therefore,
In the case of binary image data obtained by performing pseudo halftone processing on multi-valued image data, the human eye can obtain multi-valued image data equivalent to the original image by using the distribution state of the binary data. it can.

More specifically, the density of each pixel is determined by scanning the original image through a scanning window of a specific size and detecting the distribution state of nearby black pixels for each pixel. As an example, a case where a scanning window of 5 × 5 pixels is used will be described with reference to FIG.

 Each rectangle in the figure represents a pixel.

Here, the multi-value data I of the center pixel (x, y) of the scanning window
_P is the binary data I ' _3P (x-2, y-2), I' in the scanning window.
_It is obtained by weighting _3P (x + 2, y + 2) according to each position and taking the sum. Here, the binary data I '(x, y) indicates a value on the coordinates (x, y) in the image.

The weight coefficient is determined based on the distance between the sampling point A and each pixel. FIG. 11 shows an example of the weight coefficient.

Accordance connexion, halftone conversion unit 300 by the image data of the 25 fractions in Figure 10 type, calculated therewith, the product sum of the weighting coefficients shown in FIG. 11, multi-valued data I _3-Way Get.

Therefore, the calculation in the halftone conversion unit 300 is specifically as follows.

Q (x, y) = Σα · R O '(i, y) R O (x, y) = Σβ · Q (x, i) where, Q (x, y) coordinates (x-2, y ) ~ (X + 2, y)
Q (x, y−
2) The product-sum result of Q (x, y + 2) is the product-sum result for 25 pixels.

Next, a specific configuration will be described. FIG. 12 is a block diagram showing an example of the internal configuration of the halftone conversion section 400.

In the figure, reference numeral 801 denotes one output line from the output data selector 700, which is a signal line for inputting the binary data R _O '. The input binary data R _O ′ is sent to the primary adder 806 and the line memory 811.

Now, from the signal line 801, the coordinates in the image (x + 3, Y + 2)
Consider the case where binary data R _O ′ (x + 3, Y + 2) is input. Each of the four line memories shown here functions as a delay unit for storing binary data for one scanning line. Therefore, the binary data R _O ′ (x + 3, Y
When +2) is input, the line memory 811
_Output R _O ′ (x + 3, Y + 1) from the line memory 8
From 12 to 814, R _O ′ (x + 3, Y) to R _O ′ (x
+3, Y-2) is output.

On the other hand, the primary adder 806 is an arithmetic unit for obtaining a one-dimensional product-sum result Q.

When the weighting factors are the values shown in FIG. 11, the following values are used as the weighting factors α and β, respectively.

α = 1,2,4,2,1 β = 1,2,4,2,1 Therefore, in this case, the output Q (x, y
+2) is as follows.

Q (x, y + 2) = R O '(x + 2, Y + 2) + R O (x-2, Y + 2) + 2 × (R O' (x + 1, Y + 2) + R O (x-1, Y + 2)) + 4 × (R O '(X, Y + 2) An example of the primary adder 806 for executing this processing is shown in Fig. 13. In the figure, 831, 832, 833, 834, 835 are latches 841, 842, 843, respectively, soft registers, 860 is an adder, and 861 is an operation result G. This is a signal line for outputting (x, y + 2).

The input value R _O '(x + 3, Y + 2) is sequentially held in latches 431 to 435 connected in series in five stages.

At this time, the held data R _O '(x + 2, Y + 2) to R _O ' (x-2, Y + 2) of each latch are output from the data signal lines 965 to 869. The outputs from the latches 831 and 835 are
The output from the latches 832, 833, 834 is sent to the shift registers 841, 842, 843. Here, of the three shift registers, 841 and 843 shift by 1 bit, and 842 shifts by 2 bits. As a result, the adder _{860, R O '(x + 2} , Y + 2), R O' (x-2, Y + 2), 2 × R O '(x + 1, Y + 2), 2 × R O' (x-1, Y + 2) and 4 × R _O ′ (x, Y + 2) are input, and Q (x, y) is output.

This processing can also be realized using a ROM. In this case, outputs from the five latches are input as addresses and multi-value data Q (x, y) is output.

The other primary adders 812, 813, 814, and 815 in FIG. 7 can be realized by the same configuration. As a result, signal lines 881,882,883,
From 884,885, Q (x, y + 2), Q (x, y + 1),
Q (x, y), Q (x, y-1), and Q (x, y-2) are output.

This Q is subjected to the product-sum operation using the aforementioned β.
As in the primary adder described above, signal lines 881 and 885 are connected to adders 815.
882,884 is a shift register 882,8
Connected to 84, 883 is a shift register 8 that performs 2-bit shift
Enter the data in 16. As a result, the adder 815 has G (x, Y + 2), G (x, Y−2), 2 × G (x, Y + 1), 2 × G (x, Y−1), and 4 × G (x , Y) and R _O (x, y) is output.

In the case of displaying an image, particularly when a high-speed display is required, the method using the line buffer or the like,
In some cases, the processing speed is insufficient. In this case, the conversion process can be executed quickly by using only the above-described temporary addition unit 806.

Finally, the configuration of the print image conversion unit 850 will be described. The print image conversion unit 890 has a function of inputting binary color image data and outputting data in a format suitable for a data printing device 870 such as a color printer connected to the system. When the connected printer inputs binary color image data, the print image converter 850 does nothing. On the other hand, when inputting multi-valued color image data, the print image conversion unit 850 inputs three-plane binary color image data R _O ′, G _O ′, and B _O ′, The color image data R _O , G _O , and B _O are output. In this case, the operation principle of the print image conversion unit 850 is the same as that of the display image conversion unit 840 described above, and the apparatus can be realized with the same configuration.

As described above, according to the apparatus and method described above, a color image,
In particular, a color image processing device that efficiently accumulates images containing a mixture of monochrome portions such as documents, has the function of displaying monochrome images at high speed when searching for contents, and can maintain compatibility with conventional devices for monochrome binary images. Can be realized.

In this embodiment, the color / monochrome identifying switching F _CM '
Was stored as it was, but luminance data was stored in addition to the R, G, and B data, and the difference between the luminance data and the G data resulted in F
A method of expressing _CM 'can also be used.

〔The invention's effect〕

According to the present invention, a color image, particularly an image in which a monochrome portion such as a document or a thin turn such as a character is mixed is efficiently stored, and a function of displaying a monochrome image at a high speed at the time of content search is provided. A color image processing device having compatibility with a device for a value image can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of the basic configuration of the apparatus, FIG. 2 is a diagram showing the configuration of a color identification unit, FIG. 3 is a diagram showing the configuration of a binarization processing unit, and FIG. FIG. 5 is a diagram mainly showing the distribution of coefficients used in the mean error minimization method, FIG. 5 is a diagram showing the operation of the input data selector, and FIG. 6 is a diagram showing data for writing binary image data on an optical disk. FIG. 7 is a diagram showing an example of a positional relationship of a directory, FIG. 7 is a diagram showing an example of a directory configuration when binary image data is placed on an optical disk, and FIG. 8 is a diagram showing an image input from an image reading unit. FIG. 9 shows the operation of the output data selector when displaying. FIG. 9 shows the operation of the output data selector when displaying the image stored in the optical disk. FIG. 10 shows the binary image. Diagram for explaining the window when restoring halftone image data from data FIG. 11 is in restoring halftone image data from the binary image data, shows an example of a heavy coefficients, FIG. 12 is a diagram illustrating a configuration example of a display image converting unit, the
FIG. 13 is a diagram illustrating a configuration example of a display image conversion unit used for displaying an image at high speed.

──────────────────────────────────────────────────の Continuing from the front page (72) Inventor Hiromichi Fujisawa 1-280 Higashi Koigakubo, Kokubunji-shi, Tokyo Inside the Hitachi, Ltd. Central Research Laboratory (72) Inventor Satoshi Ito 2880 Kozu, Kofu, Odawara-shi, Kanagawa Prefecture (72) Inventor Hidefumi Masuzaki 2880 Kofu, Odawara City, Kanagawa Prefecture Inside Odawara Plant, Hitachi, Ltd. (72) Inventor Yasuo Kurosu 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Hitachi, Ltd.Microelectronics Equipment Development Research (56) References JP-A-61-214061 (JP, A) JP-A-60-140471 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G06T 1/00 G06T 5 / 00 H04N 1/21

Claims (8)

(57) [Claims] An image input unit for inputting a color image as three pieces of multi-valued image data in an RGB format, and connected to the image input unit to convert the multi-valued image data into binary image data by pseudo halftone processing A storage unit that stores the binary image data; a storage control unit that is connected to the binary processing unit and the storage unit and that controls writing and reading of the binary image data And for each pixel in a scan window of a specific size in the binary image data read from the storage unit, the distance from the center pixel of the scan window for each pixel And the binary data of the center pixel is obtained based on the sum of the products of all the pixels in the scanning window. Image data in RGB format A multi-value processing unit for converting the image data into data
A color document image processing system having a display unit for displaying as RGB image data. 2. An image processing apparatus which handles a document image including a color image as digital data.
Means for independently binarizing multi-valued color image data in R, G, and B formats; means for recording the binarized image data as a plurality of binary image data; 2. A device according to claim 1, further comprising means for selecting and outputting only a specific one of the plurality of binary image data.
The color image processing system as described. 3. A color image processing apparatus according to claim 1, wherein said means for determining whether each of the input binary image data is a monochrome image or a color image is provided, and a determination result is provided for each pixel. A color image processing system having means for recording as binary data. 4. A color image processing apparatus according to claim 1, further comprising means for designating the following four modes according to a target image, and for switching the data transfer process according to each mode. A color image processing system characterized by the following. Mode 1: Only G data is selected from RGB format data and stored. Mode 2: Each of the RGB multivalued data is binarized independently by pseudo halftone processing, and three binary image data resulting from the binarization are stored. Mode 3: From each of the RGB image data, it is determined whether each area of the target image is a monochrome area or a color area. In the monochrome area, only G is accumulated and R and B data are set to 0,
In the case of a color area, each pixel is quantized into one or two specific colors, and data of other colors is set to 0. Mode 4: Each of the RGB multi-valued data is independently binarized by pseudo halftone processing to determine whether each part of the target image is a monochrome area or a color area, and the binary data of the discrimination result is determined. It is stored together with the binary image data. 5. A color image processing apparatus according to claim 1, wherein said means for binarizing the multi-valued RGB data includes means for executing a plurality of types of binarization processing systems including pseudo halftone processing. And a means for selecting one of the plurality of binarization processing methods. 6. A color image processing apparatus according to claim 5, wherein said means for selecting a binarization processing method is means for obtaining a characteristic amount of each part of the input image; A color image processing system comprising: a determination unit; and a unit that switches a binarization method according to a talk determination result. 7. A color image processing system according to claim 1, wherein the means for switching the multi-valued color image data includes means for performing a simple binarization process using a fixed threshold value.
Means for performing pseudo halftone processing, means for switching between the two systems, means for determining which part of the target image belongs to a halftone image such as a photograph of a binary image such as a character,
A color image processing system comprising means for determining whether a color image or a monochrome image is to be printed, and means for performing simple binarization processing only on a portion determined to be a monochrome image and a binary image. . 8. The multi-value processing section includes a first adding section connected to the accumulation control section, and one multi-level conversion section connected to the accumulation control section for one scanning line of the scanning window including five pixels. A first line memory for storing binary data, a second adder connected to the first line memory,
A second line memory connected to the first line memory and storing binary data for one scanning line of the scanning window composed of five pixels; and a third line memory connected to the second line memory. An adder,
A third line memory connected to the second line memory and storing binary data for one scanning line of the scanning window composed of five pixels; and a fourth line memory connected to the third line memory. An adder,
A fourth line memory connected to the third line memory and storing binary data for one scanning line of the scanning window composed of five pixels; and a fifth line memory connected to the fourth line memory. An adder, a first shift register that shifts the output of the second adder left by one bit, a second shift register that shifts the output of the third adder left by two bits, A third shift register that shifts the output of the adder left by one bit, the first adder, the first shift register, the second shift register, the third shift register, and the fifth adder An adder that outputs the sum of the data as multivalued data, wherein the first to fifth adders are respectively connected to a first latch that receives input data and the first latch. A second latch and the second latch A third latch connected to the third latch, a third latch connected to the second latch, a first shift register for shifting the output of the second latch left by one pit, and a third latch connected to the third latch; A fourth latch, a second shift register that shifts the output of the second latch left by two pits, a fifth latch connected to the fourth latch, and an output of the fourth latch of 1
A third shift register that shifts the pit to the left,
Output of the first shift register and the second shift register.
2. The color image processing system according to claim 1, further comprising an adder that outputs a sum of the first shift register, the third shift register, and the fifth shift register as an output of the adding unit.