JP4571066B2 - Image processing apparatus and image reading apparatus - Google Patents

Description

  The present invention relates to an image processing apparatus and an image reading apparatus including the image processing apparatus.

High compression PDF (Portable Document Format) recognizes the character part and the image part of the document and compresses them with a compression method suitable for each, so that the file size is smaller than normal PDF and the image quality is less deteriorated. It is possible to create. However, the high-compression PDF has a drawback that the processing time is long because the character portion and the image portion are separated and compressed separately.
On the other hand, the technique disclosed in Patent Document 1 relates to an image discrimination method for automatically discriminating whether a document is a photographic image or a drawn image. Such a technique automatically identifies a photographic image and a drawn image, and performs a color reduction process on the drawn image.
JP 2002-015318 A

However, the technique of Patent Document 1 is intended to improve the image quality, and is not intended to reduce the file size by compression or the processing time.
Therefore, an object of the present invention is to generate a file having a shorter processing time and a smaller file size than a conventional high-compression PDF for a specific type of document.
More specifically, for example, a document that is slightly colored with a marker or the like is automatically determined for a black and white text document, and a color reduction process is performed on these documents to process more than a highly compressed PDF. The purpose is to create files that reduce time and reduce file size.

In order to achieve the above object, the invention according to claim 1 is a color number determination unit that determines the number of colors used in a document from image data, and when the number of colors used is equal to or less than a predetermined number by the determination. The color reduction processing means for performing color reduction processing for reducing the image data to two colors of black and white, the data compression means for compressing the image data after the color reduction processing, and the number of colors used is greater than the predetermined number of colors by the determination. And an image processing unit that performs processing for creating a highly compressed PDF of the image data .
According to a second aspect of the present invention, in the image processing apparatus according to the first aspect, the color number determining means determines a color palette creating means for creating a color palette from the image data, and determines the number of palettes in the color palette. And a pallet number determining means.
According to a third aspect of the present invention, in the image processing apparatus according to the first or second aspect, the color reduction processing means uses image data to be reduced when the predetermined number of colors is 3 or less by the determination. It is determined that it exists.
The invention of claim 4 is an image reading apparatus is characterized in that example Bei an image processing apparatus according to any one of claims 1 to 3.

  According to the present invention, it is possible to generate a file with a shorter processing time and a smaller data size than conventional high-compression PDF by performing color reduction processing only for image data in which colors other than black and white are not used much. it can.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing a schematic configuration of a digital copying machine according to an embodiment of the present invention. Referring to FIG. 1, a digital copying machine 1 implements the image reading apparatus of the present invention, and includes a CPU 2. The CPU 2 is connected to the memory unit 3, the FAX control unit 4, and the LAN control unit 5 through the bus 26. In addition, the bus 26 has an external storage device 14 and an external media input / output device 15 via the input / output device control unit 6, a storage device 9 via the storage device control unit 7, and print control via the image processing control unit 8. The unit 10, the image reading control unit 11, the input control unit 12, and the display control unit 13 are connected to each other.
A printer engine 16 is connected to the print control unit 10, a scanner 17 is connected to the image reading control unit 11, a display device 18 is connected to the display control unit 13, and an operation input device 19 is connected to the input control unit 12. A voice input device 20 is connected.
A FAX line 23 is connected to the FAX control unit 4. The LAN control unit 5 is connected to the PC 24 and the workstation 25 via the LAN, and is connected to the Internet 21 via the communication control unit 22.
The operation input device 19 includes a touch panel and key buttons, and can input information by pressing the touch panel and key buttons. The display device 18 includes a touch panel, CRT, liquid crystal, and the like. The voice input device 20 is composed of a microphone and can be input by voice. The storage device 9 is composed of a hard disk or the like. The memory unit 3 includes various ROMs and RAMs. Media that can be input / output from the external media input / output device 15 are CD-ROM, flexible disk, USB memory, multimedia card, memory stick, SD memory card, and the like. The printer engine 16 is configured by a laser printer, an inkjet printer, or the like that can perform color printing and double-sided printing.
With the configuration as described above, the digital copying machine 1 can realize various functions such as reading an image of an original with the scanner 17, printing out the image with the printer engine 16, and transmitting / receiving a FAX.

Next, contents of characteristic processing executed by the digital copying machine 1 will be described. FIG. 2 is a flowchart for explaining this process.
First, an image of a document is read from the scanner 17 (S1). Then, the image processing control unit 8 receives the read scanned image (S2). Then, the image processing control unit 8 receives the reading condition initial value (SCANERSETINGS) (see Table 1) stored in the memory unit 3 (S3). Specifically, when the reading condition is “automatic” (SCANERSETINGS = 0), the image processing control unit 8 determines whether or not to perform color reduction processing (S5) described later from the scanned image. Table 1 is a table showing data items of the memory unit 3 in which various setting values are stored.

Next, the image processing control unit 8 creates a color palette from the scanned image (S4). This is realized by a well-known technique, and color palettes are created for the number of representative colors used in the scanned image. This color palette is generated in order to analyze how many colors are included in the image of the document, and the color reduction process is not actually performed.
Then, the image processing control unit 8 determines whether or not to perform automatic color reduction from the color palette (S5). This is determined from the comparison values of R (red), G (green), and B (blue) for color reduction processing determination and the number of colors for color reduction processing determination.
Then, it is determined from the color palette created in step S4 whether the scanned image is a color image or a monochrome image. First, if the difference between R, G, and B values is less than 10 (RGB <10) (Y in S6), the palette is determined to be color, and the process of step S7 is performed. If it is larger (N in S6), it is determined as black and white, and the process of step S9 is performed.
In step S7, the number of palettes determined to be color in step S6 is determined. If there are three or less (CHECK COLOR <4) (see Table 1) (Y in S7), the process in step S8 is performed. If there are more than three (N in S7), the process in step S9 is performed. In step S8, the image processing control unit 8 executes a color reduction process based on the color palette generated in step S4. Here, a color reduction process which is a well-known technique is executed. In this color reduction process, the number of colors after color reduction is reduced so that the number of colors shown in NUM_COLOR (see Table 1) is “2”. In step S9, the image processing control unit 8 performs image processing other than the color reduction processing, and generates an image data file. For example, a high-compression PDF creation process, which is a well-known technique, is performed.
When the color reduction process is executed, the image processing control unit 8 compresses the file that has been reduced in step S8 and generates a file (S10).
Since it has been found that the color-reduced file is a file with a small number of colors, it is possible to generate a file smaller in size than a high-compression PDF by compressing it in PNG format, etc. It is. Also, the processing time can be shortened as compared with the high compression PDF.
The image data processed as described above is stored in the storage device 9 (S11).

FIG. 3 is a plan view of a screen display of the touch panel when a touch panel is used as the operation input device 19. Each input can be input by pressing a touch panel or a key button. However, input from the voice input using the voice input device 20 is also possible. Here, the display transition of the touch panel when the operator actually uses the function described with reference to FIG. 2 will be described with reference to FIG.
First, a function used in the digital copying machine 1 is selected on the menu screen (FIG. 3A). If the scanner 17 is selected here, the screen moves to the screen of FIG. The screen of FIG. 3B is a screen for selecting an image output method. Since the digital copying machine 1 can perform mail transmission, shared folder transmission, document storage, FAX transmission, and the like as the output method, this output method is displayed on this screen. Select with.
In the screen of FIG. 3B, “document accumulation” is selected and the screen moves to the screen of FIG. The screen shown in FIG. 3C is a screen for setting the reading conditions of the scanner 17. When the original is set on this screen and a predetermined start button is pressed, scanning of the original in the scanner 17 is started. I can do it. On this screen, “reading condition”, “file format”, “document name”, “user name”, “password”, etc. can be set, but “reading condition” and “file format” are already set. These initial values are values stored in a storage device such as the memory unit 3, and the initial value (= 0) is set with the reading condition "automatic" and the file format "PDF" (see Table 1). . Enter "Document Name", "User Name", and "Password" as necessary. When the start button is pressed, the document is read from the scanner 17 and the image processing described with reference to FIG. 2 is performed.
When the image processing is completed and data transmission to the output destination is completed, the screen transitions to the screen of FIG. Since “accumulated document” is selected as the output destination this time, the data is stored in the storage device 9 such as an HDD.

As described above, in the digital copying machine of the present embodiment, the processing time is shorter than that of the conventional high-compression PDF by performing the color reduction process only in the case of image data in which colors other than black and white are not frequently used. A file with a small data size can be generated.
Whether or not colors other than black and white are not often used can be determined by creating a color palette and determining the number of palettes.
In addition, a file having a shorter processing time and a smaller data size than a conventional high-compression PDF can be generated for image data obtained by reading a document in which one or two colors are added to a monochrome document.

1 is a block diagram showing an electrical connection of a digital copying machine according to an embodiment of the present invention. 5 is a flowchart for explaining characteristic processing of the digital copying machine. It is a top view of the screen displayed on the touch panel of a scanning input device.

Explanation of symbols

  1 image reading device, 8 image processing device

Claims (4)

Color number determination means for determining the number of colors used in the document from the image data;
A color reduction processing means for performing a color reduction process for reducing the image data to two colors of black and white when the number of used colors is equal to or less than a predetermined number of colors according to the determination;
Data compression means for compressing the image data after the color reduction processing;
Image processing means for creating a highly compressed PDF of the image data when the number of colors used is greater than a predetermined number of colors according to the determination;
An image processing apparatus comprising: The color number determination means is
Color palette creating means for creating a color palette from the image data;
Palette number judging means for judging the number of palettes of the color palette;
The image processing apparatus according to claim 1, further comprising:   The image processing apparatus according to claim 1, wherein the color reduction processing unit determines that the image data is a color reduction target when the predetermined number of colors is 3 or less by the determination. Image reading apparatus characterized by comprising an image processing apparatus according to any one of claims 1 to 3.

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