JP2001309190A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader that can obtain a desired read image at a low cost without imposing much load onto a host computer and a communication channel by reducing a color image data quantity. SOLUTION: When read processing of an image is started, an image read unit 2 transmits read image data to an image processing unit 3. A magnification filter section 6 processes the image data received by the image processing unit 3 and stores the data to an image data memory section 7, and a pallet generating section 8 generates a pixel value histogram. The pallet generating section 8 decides color pallet data on the basis of a frequency of the pixel value data in the completed pixel value histogram and stores the data to a color pallet data memory section 9. The magnification filter section 6 processes the image data stored in the image memory section 7, sequentially transfers the data to line buffers 10, 11, 12, and a subtractive color processing section 13 replaces the received data with a color stored in the color pallet data memory section 9 to conduct subtractive color processing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus, and more particularly, to an image reading apparatus provided with an image processing means for performing color reduction processing on image data read by using an image reading means such as a scanner, a facsimile, a copying machine or the like. It relates to a reading device.

[0002]

2. Description of the Related Art In recent years, an image reading apparatus, such as a scanner, a facsimile or a copying machine, for reading a color image and outputting color image data has been used.
The reading density for capturing a clearer image has been dramatically improved. According to this type of image reading apparatus, the amount of image data to be handled increases as the reading density increases as described above. Therefore, if the read color image data is output as it is, a large amount of data will be transmitted to a communication path used for data transmission or a host computer. Results in a heavy load.

For this reason, conventionally, compression processing of color image data using JPEG or the like has been performed in an image reading apparatus, or processing for reducing the number of colors by uniformly reducing the resolution of each color component has been performed.

In addition to the above, color data to be used is determined after the read color image data is once read into a memory, and information on colors to be used is given in advance, and color reduction processing is performed based on the information.

[0005]

However, in such a conventional image reading apparatus, when a color image compression process is performed by JPEG, a distorted image is generated in an illustration document with a limited number of colors to be used. There was such a problem.

In addition, when processing is performed to reduce the number of colors by uniformly lowering the resolution of each color component, there is a problem in that the image is unnaturally colored because it is greatly affected by the color distribution of the document. .

Further, when processing for determining the type of color to be used after reading the read image data into the memory once, an enormous image memory is required, so that there is a problem that the apparatus cost is increased.

Further, when the color reduction processing is performed based on the color information given in advance, there is a problem in that natural color image data cannot be obtained depending on the type of the read image.

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and it is possible to reduce the amount of color image data to be output, without imposing a great load on a host computer or a communication path, and to obtain a desired read image at low cost. It is an object to provide an obtained image reading device.

[0010]

According to one aspect of the present invention, there is provided an image reading apparatus provided with an image processing means for performing color reduction processing of image data read by using the image reading means. Wherein the image processing means reads out the color of the image data and performs color reduction processing based on statistical information of the image.

According to the first aspect of the present invention, when the image data read by the image reading means is subjected to the color reduction processing by the image processing means, the color type to be used is determined based on the statistical information of the actual read image. Since the processing is performed, it is possible to always obtain a natural-colored read image regardless of the type of the image.

According to a second aspect of the present invention, in the image reading apparatus of the first aspect, the image processing means includes a scaling / filtering section for scaling or filtering the image data; An image memory unit for storing image data processed by the filter unit; a palette generation unit for generating a pixel value histogram from the image data processed by the scaling / filter unit; and pixel value data in the pixel value histogram A color information memory unit that stores color information determined from the frequency of the image data, a line buffer that processes the image data stored in the image memory unit by the scaling unit / filter unit, and holds the color data for each color type. A color reduction processing unit that replaces the image data for each color type held in the buffer with a color in the color information in the color information memory unit.

According to the second aspect of the present invention, in the image processing means of the first aspect, the image data is stored in the image memory unit by performing the scaling process or the filtering process on the image data by the scaling unit / filter unit. The pallet generation unit generates a pixel value histogram, and the color information memory unit stores color information determined from the frequency of the pixel value data in the pixel value histogram. The image data stored in the image memory unit is processed by the scaling / filter unit and stored in a line buffer for each color type, and the image data for each color type stored in the line buffer in the color reduction processing unit is stored in a color information memory. The color reduction processing is performed by substituting the color in the color information of the copy. As described above, since the color reduction processing that always determines the color type to be used based on the statistical information of the actual read image is performed, a read image with a natural coloring can always be obtained regardless of the type of the image.

According to a third aspect of the present invention, in the image reading apparatus according to the first or second aspect, when acquiring the color statistical information of the read image data necessary for performing the color reduction processing by the image processing means, The image reading operation is performed using an image reading operation different from the actual image reading operation.

According to the third aspect of the present invention, the statistical information of the read image data necessary for the color reduction processing is obtained in an image reading operation different from the actual image reading operation. The amount of memory can be further reduced, and the cost can be further reduced.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram illustrating a schematic configuration of an image reading device 1 according to the present embodiment. FIG.
The image reading device 1 includes an image reading unit 2 as an image reading unit, an image processing unit 3 as an image processing unit, an image memory unit 4, and an I / F unit 5.
Etc.

The image reading unit 2 has three lines C
It is composed of a CD, a CCD driver, etc., and outputs full-color image data photoelectrically converted by capturing an image toward a target image such as a color original.

The image processing unit 3 is a characteristic component of the present invention, and performs scaling processing, filter processing, color reduction processing, and the like. This image processing unit 3
The detailed configuration will be described later with reference to FIG.

The image memory unit 4 is composed of a FIFO (first-in first-out) memory capable of outputting the input image data in order. The I / F unit 5 is a unit that performs I / F (interface) processing with a host computer via a network, and includes, for example, a SCSI interface and a network interface.

FIG. 2 shows the image processing unit 3 in FIG.
FIG. 3 is a block diagram illustrating an example of a configuration. The image processing unit 3 in FIG. 2 includes a scaling / filter unit 6, an image memory unit 7, a pallet generation unit 8, a color pallet data memory unit 9 as a color information memory unit, and a line buffer (red).
10, a line buffer (green) 11, a line buffer (blue) 12, a color reduction processing unit 13, and the like.

The scaling / filter section 6 performs scaling processing and filter processing of full-color image data read and input by the image reading unit 2 described above. Further, the image memory unit 7 temporarily writes the image data processed by the scaling / filtering unit 6, and then scales the image data again.
This is a memory for reading out to the filter unit 6 and performing image processing.

The pallet generator 8 determines color information (hereinafter also referred to as color pallet data) from the frequency of the pixel value data of the image data processed by the scaling / filtering unit 6. The color pallet data memory unit 9 is referred to when performing the color reduction processing of the present invention.
This is a memory for storing the color pallet data generated by the pallet generation unit 8 described above.

Line buffers (red) 10, (green) 11,
(Blue) 12 temporarily stores the pixel values of the image data processed by the scaling / filtering unit 6 for each color, and outputs the pixel values to a color reduction processing unit 13 described later. The color reduction processing section 13 determines a representative color on the color pallet data closest to the original image and performs a color reduction process on the color image data.

Next, the operation will be described. FIG. 3 is a flowchart illustrating an operation of performing both actual image reading and acquisition of statistical information on the color of the read image. First, as shown in FIG. 3 (see also FIGS. 1 and 2), when reading processing of a color image is started in the image reading apparatus 1 by an instruction from a host computer or the like (not shown) (Step S).
1), the image reading unit 2 in FIG. 1 photoelectrically converts the read image, and the image data is sent to the image processing unit 3.

In the image processing unit 3, image data obtained by subjecting the input full-color image data to scaling / filtering by the scaling / filtering unit 6 is stored in the image memory unit 7. At the same time, the pallet generation unit 8 generates a pixel value histogram based on the image data processed by the scaling / filtering unit 6 (step S2).

In this way, when the above processing is performed until all the image data is stored in the image memory unit 7 (step S3), the pallet generation unit 8 completes the pixel value histogram. Then, the pallet generation unit 8 determines the color pallet data from the frequency of the pixel value data in the completed pixel value histogram (Step S4), and stores the color pallet data in the color pallet data memory unit 9. This means that the statistical information of the color of the read image has been obtained.

Thereafter, after the image data stored in the image memory unit 7 is processed by the scaling / filter unit 6,
Line buffers of each color type (red) 10, (green) 11,
(Blue) 12 sequentially (step S
5). Then, the image data in each of the color line buffers 10, 11, and 12 is subjected to the color reduction processing in the color reduction processing unit 13 by replacing the image data with the color stored in the color pallet data memory unit 9 by using a neighborhood search method or the like. This is performed (step S6).

The color image data subjected to the color reduction processing is
The data is transferred and stored in the image memory unit 4 (step S7). The color-reduced image data stored in the image memory unit 4 is transferred to the I / F by an instruction from a host computer or the like.
The data can be transferred to the outside via the unit 5 (step S8).

As described above, according to this embodiment, when the image processing unit 3 performs the color reduction processing on the image data read by the image reading unit 2, the scaling / filter unit 6 of the image processing unit 3, A color reduction process for determining a color type to be used based on statistical information of an actual read image by an image memory unit 7, a palette generation unit 8, a color palette data memory unit 9, line buffers 10, 11, and 12, and a color reduction processing unit 13. Is performed, it is possible to always obtain a read image of a natural coloring regardless of the type of the image.

Next, FIG. 4 is a flowchart for explaining the operation for acquiring the color statistical information of the read image separately from the actual image reading. In FIG. 4, unlike the case of FIG. 3, an operation of acquiring the statistical information of the color of the read image is performed, and then the actual image reading operation is performed.
First, as shown in FIG. 4 (see also FIGS. 1 and 2), when an instruction is given from a host computer or the like (not shown), a color image for generating color pallet data by a control unit (not shown) of the image reading apparatus 1 is provided. Is started (step S11). Also in this case, image data obtained by the image reading unit 2 of FIG. 1 photoelectrically converting the read image is sent to the image processing unit 3.

In the image processing unit 3, the input full-color image data is scaled or filtered by the scaling / filter unit 6, and a pixel value histogram is generated by the palette generation unit 8 based on the image data (step). S12). When the first reading is completed, the pixel value histogram is completed, and the color pallet data is determined from the frequency of the pixel value data in the completed pixel value histogram (step S13). Then, the determined color pallet data is stored in the color pallet data memory 9.
To be stored. This means that the color statistical information of the read image has been obtained in advance.

Next, when performing a target image reading process (step S14), image data obtained by subjecting the target image to photoelectric conversion by the image reading unit 2 is sent to the image processing unit 3. The image processing unit 3 scales image data.
The image data subjected to the scaling processing or the filtering processing in the filter unit 6 is converted into a line buffer (red) 10 of each color type,
(Green) 11 and (blue) 12 are sequentially transferred (step S)
15).

Then, each color line buffer 10, 11,
The image data in the image data 12 is subjected to a color reduction process by replacing it with a color stored in the color pallet data memory unit 9 by using a neighborhood search method or the like in the color reduction processing unit 13 (step S16). .

The color image data subjected to the color reduction processing is
The data is transferred to and stored in the image memory unit 4 (step S17). The color-reduced image data stored in the image memory unit 4 is input to the I / O by an instruction from the host computer or the like.
The data can be transferred to the outside via the F unit 5 (step S18).

As described above, according to this embodiment, the statistical information of the read image data necessary for the color reduction processing is obtained by an image reading operation different from the actual image reading operation. The required memory capacity of the image memory unit 7 can be further reduced, and the cost can be further reduced.

In the above-described embodiment, a scanner, a facsimile, a copying machine, and the like are described as examples of the image reading apparatus. However, the present invention is not limited to this, and can read and output a color image. If so, various devices can be applied.

[0037]

As described above, according to the first aspect of the present invention, when the image data read by the image reading means is subjected to the color reduction processing by the image processing means, it is used based on the statistical information of the actual read image. Since the color reduction processing of determining the type of color to be performed is performed, it is possible to always obtain a natural-colored read image regardless of the type of the image.

According to the second aspect of the present invention, the image processing means includes a scaling / filtering unit, an image memory unit, a palette generation unit, a color information memory unit, a line buffer, and a color reduction processing unit. Since the color reduction processing for determining the color type to be used based on the statistical information is performed, it is possible to always obtain a natural-colored read image regardless of the image type.

According to the third aspect of the present invention, in the image reading operation different from the actual image reading operation, the statistical information of the read image data required for the color reduction processing is obtained. The amount of memory can be further reduced, and the cost can be further reduced.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a schematic configuration of an image reading apparatus according to an embodiment.

FIG. 2 is a block diagram illustrating a configuration example of an image processing unit in FIG.

FIG. 3 is a flowchart illustrating an operation of simultaneously performing actual image reading and acquisition of color statistical information of a read image.

FIG. 4 is a flowchart illustrating an operation for acquiring statistical information of the color of a read image separately from actual image reading.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Image reading apparatus 2 Image reading unit (image reading means) 3 Image processing unit (image processing means) 4 Image memory unit 5 I / F unit 6 Magnification / filter unit 7 Image memory unit 8 Palette generation unit 9 Color palette data memory Section (color information memory section) 10, 11, 12 Line buffer (red, green, blue) 13 Color reduction processing section

Continued on front page F-term (reference) 5B057 AA11 BA02 CA01 CA08 CA12 CA16 CB01 CB08 CB12 CB16 CC01 CD05 CE06 CE16 CH11 DA17 DB02 DB06 DB09 DC23 DC25 DC36 5C077 MP08 PP01 PP20 PP31 PP32 PQ19 PQ23 PQ24 RR06 5C0 LALA LA00 LA00 LA00 LA00 LA00 LA02 MA01 MA02 NA10 NA25 PA01 PA02

Claims (3)

[Claims] 1. An image reading apparatus comprising image processing means for performing color reduction processing of image data read by using image reading means, wherein said image processing means reads a color of said image data based on statistical information of the image. An image reading apparatus for performing color reduction processing. 2. The image processing means includes: a scaling / filter unit for scaling / filtering the image data; an image memory unit for storing image data processed by the scaling / filter unit; A palette generation unit that generates a pixel value histogram from the image data processed by the scaling / filter unit; a color information memory unit that stores color information determined from the frequency of the pixel value data in the pixel value histogram; The image data stored in the image memory unit is processed by the scaling / filtering unit, and a line buffer for holding each color type is stored in the color information memory unit. 2. A color reduction processing unit for replacing a color in color information with a color in the color information.
The image reading device according to claim 1. 3. The method according to claim 1, further comprising the step of acquiring statistical information on the color of the read image data required for performing the color reduction processing by said image processing means.
The image reading apparatus according to claim 1, wherein the image reading operation is performed using an image reading operation different from an actual image reading operation.