JPH07322251A - Image processing unit and data compression method - Google Patents

Abstract

PURPOSE:To improve the balance between image quality and a data capacity by selecting a compression rate of image data with priority of image quality to be low and selecting a compression rate of image data with priority of data capacity to be high as to image data in one pattern. CONSTITUTION:Coordinates 101-104 of an area A are used for information representing the position and shape of the area A. The coordinate information of each area is acquired in advance and stored in a system memory 15 in relation to a compression rate as a table form. A data compression rate is set high for a background G and a compression rate of data of, e.g. the area A is selected to be low to avoid loss of image quality. The user enters the compression rate and coordinate information representing the area corresponding to the compression rate by using a key board 14 prior to image pickup and stores them in a memory 15 via a CPU 8. Then the user gives a command of the entry of image pickup result to the CPU 8. The CPU 8 receiving the command receives output data from an A/D converter 6 and applies compression processing to the data and the result is written in a video memory 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus for compressing image data and a data compression method thereof.

[0002]

2. Description of the Related Art Conventionally, in an image processing apparatus, for example, an image processing apparatus used in an inspection apparatus, an image of a subject is picked up by an image pickup device such as a CCD camera, and the image pickup result is input. Recently, this imaging result is often input in the form of a color image signal for each pixel (hereinafter collectively referred to as image data).

[0003]

However, when a subject is three-dimensionally imaged in color from multiple directions, the imaged result is a plurality of screens and a large amount of color image data. Therefore, the memory for temporarily storing the image data prior to the actual inspection process has a large capacity,
There has been a problem that the inspection process itself takes a long time.

In order to reduce the memory capacity, an image processing method for uniformly compressing image data for one screen at a specific compression rate has been proposed, but in this case, image deterioration will occur.

Therefore, in view of the above points, an object of the present invention is to provide an image processing apparatus and a data compression method thereof in which the deterioration of the image quality such as inspection and the memory capacity are well balanced.

[0006]

In order to achieve such an object, the invention of claim 1 divides one screen into a plurality of areas in advance, and an area showing the position and shape of the divided areas. Information, a storage unit that stores a data compression rate corresponding to the area indicated by the area information, and image data for one screen to be image-processed are stored in the area for each area indicated by the area information. And a compression means for compressing at the corresponding data compression rate.

According to a second aspect of the present invention, one screen is divided into a plurality of areas in advance, and area information indicating the position and shape of the divided areas and a data compression rate corresponding to the area indicated by the area information are displayed. It is stored in a storage medium, and image data for one screen to be subjected to image processing is compressed by an arithmetic processing unit for each area indicated by the area information at the data compression rate corresponding to the area. And

[0008]

According to the first and second aspects of the present invention, the image data of one screen is compressed at different compression ratios for each area to distinguish the image data of the image quality priority from the image data of the capacity priority. Balance.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 shows an example of a system configuration of an inspection apparatus to which the present invention is applied. In FIG. 1, an image pickup device such as a CCD camera is used for the image input unit 3. The image input unit 3 inputs the image of one screen of the subject 1 by capturing the light projected from the illumination device 2 and reflected by the subject 1.

An analog image pickup result of the image input section 3 is amplified by an amplifier 5 to be converted into an analog / digital (A /
D) The converter 4 converts the image data into digital image data for each pixel, and inputs the image data to the CPU 8. The CPU 8 performs compression processing according to the present invention, which will be described later, as compression means and an arithmetic processing device of the present invention on input image data, and stores the compressed image data in the image memory 7.

The system memory 15 performs a process executed by the CPU 8, for example, a process of compressing image data sent from the image input unit 3 and storing it in the image memory 7, the image display unit 1.
1, a system program that defines a process of transferring image data to the image recording unit 12 and the image communication unit 13 and a process of performing a visual inspection of a subject using the image data of the image memory 7 are stored. In this embodiment, the image pickup screen is divided into a plurality of areas in advance, and the data compression rate is set for each area. The coordinate information indicating the divided area and the compression rate are the system memory (storage means and storage medium of the present invention) 1
5 is stored.

On the image pickup screen of the subject whose image pickup position is fixed as shown in FIG. 2, closed sections A, B ... Enclosed by the contour image are generated.
~ 104 are treated as information indicating the position and shape of the area A. The coordinate information of each of these areas is acquired in advance,
It is stored in the system memory 15 in association with the compression rate in the form of a table as shown in FIG.

Since the background G is not an inspection target, the data compression rate is set high. In addition, the part to be inspected,
For example, with respect to the area A, the data compression rate is set low so that the image quality is not impaired.

From the keyboard 14, an operation instruction for the CPU 8, for example, an instruction for activating the above-mentioned various system programs is input. The image display unit 11 visually displays the image data sent from the CPU 8. Image recording unit 12
Reads / writes data to / from a recording medium such as a floppy disk or hard disk. An interface or the like is used for the image communication unit 13, and data communication is performed with the host computer.

The input image data storage processing executed in such a system configuration will be described with reference to FIGS. 4 and 5. FIG. 4 shows the main processing procedure of the data storage processing, and FIG. 5 shows the detailed processing procedure of steps S20 to S50 of FIG.

In FIG. 4, prior to imaging, the user inputs the compression rate and coordinate information indicating the area corresponding to the compression rate from the keyboard 14 and stores it in the system memory 15 via the CPU 8 ( S10).

Next, the user instructs the CPU 8 to input the image pickup result. In response to this instruction, the CPU 8 inputs the output data of the A / D converter 6, performs compression processing, and writes the compressed data in the image memory 7 (S20-40).

More specifically, for example, one screen has 640
In the case of x480 pixels, the CPU 1 sequentially takes in one horizontal scanning (image data of 640 pixels into the work area in the system memory 8 (S100). The pixel positions of these image data are area A and area Then, the CPU 8 determines a data group for each area and creates a data group for each area by the CPU 8. The CPU 8 compresses the data group at a compression rate corresponding to each area. Method can be used, it is not described in detail, but the process of thinning out pixels is general.

The image data compressed in this manner is stored in the storage area assigned to each area in the image memory 7 (S110).

When the image data for one horizontal scan is stored in the image memory 7 in this way, the above-described processing is repeated 480 times and the compressed image data for one screen is stored in the image memory 7 (loop of S100 to S130). processing).

Thereafter, when the user gives an instruction for image inspection via the keyboard 14, the CPU 8 causes the image memory 14 to operate.
The visual inspection for scratches is performed using the image data after compression. Further, when the image pickup screen is displayed on the image display unit 11, the data is decompressed by the procedure reverse to the above, and 640 ×
Image data of 480 pixels is created and transferred to the image display unit 11.

As described above, according to the present embodiment, prior to processing such as appearance inspection, data is compressed at different compression rates by dividing it into a necessary area and an unnecessary area. Good image quality balance.

In addition to this embodiment, the following example can be carried out.

1) In this embodiment, the data compression by thinning out the pixels has been described, but full color M colors (M is an integer), monochrome, full color N colors (N is an integer), single color, etc., regardless of the pixel thinning. It is also possible to change the data amount according to the color information as shown in. Also in this case, the CPU 8 collects the input image data for each area, and converts the input image data into image data indicated by the color information determined for each area in advance. This image data conversion process itself is well known, and those skilled in the art can easily implement the above process by replacing the data compression process with the data conversion process in the processing procedure of FIG. For reference, the correspondence between each area and the compression information (color information) is shown in FIG.

2) In this embodiment, the image data to be compressed is imaged from the subject to be inspected, but the present invention can be applied to general image data, not limited to the purpose of inspection. For example, FIG. 7 shows an example in which the compression rate is changed for each region for image data in which a map is imaged.

3) When performing the visual inspection based on the image data, it is preferable to set the area according to the inspection purpose. When inspecting labels A-2 and B-4 such as bottles and cups as shown in FIG. 8, image data in which full-color pixel thinning is not performed, image data in which full-color pixel thinning is performed on the bottle itself, and background are displayed. It may be possible to convert it to binary data.

4) In this embodiment, the user has specified the area corresponding to the compression rate, but the area can be automatically divided.

A contour line is generated between the background and the subject on the screen, and a technique for extracting the contour line image is also established.
When a contour line image is acquired using this technique, the contour line image can be used as information indicating the area position and size.

[0030]

As described above, according to the present invention, it is possible to set a low compression rate for image data with priority on image quality and a high compression rate for image data with priority on data capacity for image data in one screen. As a result, the balance between the image quality and the data capacity becomes good.

[Brief description of drawings]

FIG. 1 is a block diagram showing a system configuration of an image processing apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing screen division areas.

FIG. 3 is an explanatory diagram showing a correspondence relationship between screen division areas and compression rates.

FIG. 4 is a flowchart showing a processing procedure executed by a CPU 8 in FIG.

5 is a flowchart showing a processing procedure executed by a CPU 8 of FIG. 1. FIG.

FIG. 6 is an explanatory diagram showing a correspondence relationship between another screen division area and a compression rate.

FIG. 7 is an explanatory diagram showing a correspondence relationship between another screen division area and a compression rate.

FIG. 8 is an explanatory diagram showing a correspondence relationship between another screen division area and a compression rate.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Subject 2 Illumination device 3 Image input unit 4 Image processing device 5 Amplifier 6 A / D converter 7 Image memory 8 CPU 9 D / A converter 10 Input / output (i / o) interface 11 Image display unit 12 Image recording unit 13 Image Communication Section A-1, A-2, B-1, B-2, B-3, B-4 Contour

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Claims (2)

[Claims] 1. A screen is divided into a plurality of areas in advance, and area information indicating a position and a shape of the divided areas,
Storage means for storing a data compression rate corresponding to the area indicated by the area information, and image data for one screen to be subjected to image processing are provided for each area indicated by the area information, corresponding to the area. An image processing apparatus comprising: a compression unit that compresses at a data compression rate. 2. One screen is divided into a plurality of areas in advance, and area information indicating a position and a shape of the divided areas,
A data compression rate corresponding to the area indicated by the area information is stored in a storage medium, and image data for one screen to be image-processed is stored in the area corresponding to the area for each area indicated by the area information. A data compression method for an image processing device, characterized in that the data is compressed by an arithmetic processing device at a data compression rate.