JPH0237481A - Subject color discriminator - Google Patents

Abstract

PURPOSE:To correctly discriminate the color of a moving body by converting a picture signal into a frequency area, obtaining the difference between the result of conversion and frequency converting data of the stationary condition of a registered subject to detect a moving direction, compressing the picture signal according to detected directionality, and discriminating the color. CONSTITUTION:The input picture signal is converted into the frequency area by a two-dimensional Fourier transforming means 25, and the frequency converted data are inputted to directionality detecting means 26, they are compared with the frequency converted data of the subject picture in the stationary condition registered beforehand, and by discriminating the characteristic difference of the frequency converted data by means of object moving, and the moving direction of the subject is detected. Here, based on the obtained moving direction, by spatially compressing the input picture signal by a directionality compressing means 27, the picture compressed corresponding to the moving quantity of the subject clearer than the input picture is restored. Thus, the clear still picture can be obtained, and the correct color information can be extracted by a color discriminating means 28.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a subject color discrimination device used in industrial measurement systems, inspection systems, image processing systems, and the like.

(Conventional technology) Conventionally, in determining the color of a product, a colorimeter is used when the product can be directly contacted, and a color IT is used when contact is not possible.
V (industrial television) or the like was used to capture the image as an image and perform color discrimination.

This is fine if the subject is stationary, but if the subject is moving, the image captured by a color ITV or the like will also flow in one direction. Since this is not an image representing the original subject, it causes errors in color discrimination.

A block diagram of a conventional system is shown in FIG. 3 to explain it in detail.A color image signal obtained by a sensor 12 such as a color ITV under the control of a dedicated controller 11 is transmitted to an image input interface 1 equipped with an image memory, for example.
3 to the color discrimination unit 14, where the color of the subject image is discriminated.

At this time, it takes approximately 33 m to capture images at video rate.
sec, and if the subject moves during this time, the image will be blurred, making it impossible to obtain an image of the subject that allows correct color determination.

(Problems to be Solved by the Invention) As described above, in conventional color discrimination systems, when the subject is a moving object, images are acquired flowing in one direction, which causes the colors of the subject image to be mixed. Accurate color measurements were difficult.

SUMMARY OF THE INVENTION The present invention has been made to eliminate the above-mentioned drawbacks, and an object of the present invention is to provide an object color discrimination device that can accurately discriminate colors even if the object is a moving object.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, a subject color discrimination device according to the present invention includes an image input means for capturing a subject as a color image signal, and an image obtained by this means. A two-dimensional Fourier transform means converts the signal into a frequency domain, and the direction of movement of the subject is determined by calculating the difference between the frequency transform data obtained by this means and the frequency transform data of the still state of the subject registered in advance. Directionality detection means for detecting directionality, directionality compression means for compressing the image signal according to the directionality detected by this means, and color discrimination means for discriminating colors from the image signal compressed by this means. It is composed of

(Operation) In the object color discrimination device having the above configuration, when the object moves, the object image flows in a fixed direction, so that characteristics appear in the two-dimensional image spatial frequency. Therefore, the input image signal is converted into a frequency domain by a two-dimensional Fourier transform means, and the frequency converted data is inputted to the directionality detection means, and compared with the frequency converted data of a still subject image registered in advance. The moving direction of the subject is detected by finding characteristic differences in the frequency conversion data due to the movement of the subject. By spatially compressing (geometric transformation) the input image signal using the directional compression means based on the movement direction obtained here, a clear image that is smaller than the input image in accordance with the amount of movement of the subject is created. Can be restored.

Therefore, a clear still image can be obtained, and accurate color information can be extracted by the color discrimination means.

(Example) An example of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 shows its configuration, and 21 is a color image input unit such as an ITV camera installed at a position to image a subject (not shown). The subject image captured by the color image input unit 21 is sent to the image input interfaces 221 to 2.
23, the image is separated into three primary colors, for example, R and CB, and stored in the memory on the interface. The image signals accumulated in these image input interfaces 221 to 223 are sequentially input to a two-dimensional Fourier transform unit 25 using, for example, an FFT (fast Fourier transform) processor, where they are subjected to two-dimensional Fourier transform and converted into a spatial frequency head area. .

The frequency transform data obtained by the two-dimensional Fourier transform section 25 is input to the directionality detection section 26 . - This directionality detection unit 26 has registered in advance frequency conversion data obtained by two-dimensional Fourier transform of a subject image acquired in a stationary state, and combines this data in a stationary state and the data from the two-dimensional Fourier transform unit 25. For example, by comparing the data by difference calculation, division, etc., and grasping the prominent spatial frequencies,
This method extracts the direction in which the input image is flowing.

The direction data obtained by the directionality detection section 26 is input to the directionality compression section 27. The directionality compression unit 27 extracts image signals from the image input interfaces 221 to 223 through the image bus 30, and converts the image signals into image signals using geometric transformation such as affine transformation based on the direction data from the directionality detection unit 26. It compresses the

The image signal compressed by the directionality compression section 27 is sent to the color discrimination section 28.
is input. As shown in FIG.
on), the brightness (I: Intensity) is determined, the image compression circuit 32 determines the average value, and the color vector output circuit 31 converts it into a vector in H9I space and outputs it. This process performs coordinate transformation of the color space that expresses colors. The color vector obtained here is sent to the display section 29 as a color discrimination result and is displayed as appropriate.

Incidentally, each of the blocks 21 to 29 described above is generally controlled by the host computer 23 via the control bus 24.

The operation of the above configuration will be explained below.

First, a still subject is imaged by the color image input unit 2I, and the image signals obtained here are subjected to two-dimensional Fourier transform by the two-dimensional Fourier transform unit 25 via the image input interfaces 221 to 223 for each RGB, It is registered in the directionality detection unit 26 as frequency conversion data in a static IL state.

Next, the color image input unit 21 inputs an image of the registered subject in a moving state, and the image input interface 22. - 223 memory sequentially. This 2
A two-dimensional Fourier transform unit 25 performs two-dimensional Fourier transform, and inputs the data as frequency-converted data in a moving state to the directionality detection unit 2B. Furthermore, the directionality detection unit 26 compares the registered frequency conversion data in a stationary state with the inputted frequency conversion data in a moving state to detect the direction in which the image is flowing.

Next, the directionality compression unit 27 compresses the image signal by affine transformation based on the detected direction. In other words, the image flowing in a fixed direction is similar to applying a directional spatial filter and averaging the image in that direction, and the above compression causes a clear image to flow in one direction again. Restored in reduced form. This compression is not limited to affine transformation, but can also be performed by performing special geometric transformation or density transformation in consideration of the movement characteristics of the subject and the characteristics of the color image input section 21.

Finally, the color discrimination device 28 extracts the color of the target object, and the display means 29 outputs and displays it. In this case, since a clear still image is obtained by compressing the image signal, color discrimination is extremely easy and accurate.

Therefore, even if the subject moves, the subject color discrimination device with the above configuration detects the flow of the input image and compresses the image signal in that direction, so it can capture an extremely clear still image. Can accurately identify colors.

Therefore, it is possible to perform measurements with few errors, and it can be used for color discrimination of an unspecified number of materials flowing on a belt conveyor in an industrial line, making it extremely versatile.

In the above embodiment, the color discrimination section 28 performs image compression, but of course the processing range may be limited without performing image compression. Furthermore, instead of the H5■ conversion, the average value of each R, G, and H image may be calculated and output as a color vector in the RGB space.

Further, in FIG. 1, the host computer 23 is used for overall control of the hardware, but a dedicated controller may also be used. Further, the image bus 30 is for high-speed transfer of image data, and the control bus 24 and host computer 23 may also be used. An operator's visual indicator may be added for direction detection, etc. Image input also uses R, G, and B signal formats.
Of course, it is also possible to use NTSC color composite if a decoder is provided at the input interface.

Of course, the same applies when the color image input section 21 moves without the subject moving.

[Effects of the Invention] As described above, according to the present invention, it is possible to provide a subject color discrimination device that can accurately discriminate colors even if the subject is a moving object.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the object color discrimination device according to the present invention, FIG. 2 is a block diagram showing details of the color discrimination section of FIG. 1, and FIG. 3 is an example of a conventional color discrimination system. FIG. 11... Controller, 12... Sensor, 13...
・Image input interface, 14...color discrimination section, 21
...Color image input unit, 221-223...Image input interface, 23...Host computer, 24...
・Control bus, 25...2D Fourier transform unit, 2G・
... Directionality detection section, 27... Directionality compression section, 28...
- Color discrimination unit, 29...Display unit, 30...Image bus, 31...Color vector output device, 32...Image compression device, 33...RGB-HS ■ Conversion device.

Claims (1)

[Claims] an image input means for inputting the subject as a color image signal; a two-dimensional Fourier transform means for converting the image signal obtained by this means into a frequency domain; Directionality detection means for detecting the moving direction of the subject by determining a difference from frequency conversion data in a stationary state; Directionality compression means for compressing the image signal according to the directionality detected by this means; A moving object color discriminating device comprising a color discriminating means for discriminating a color from an image signal compressed by this means.