JPH03258091A - Color picture signal processing method - Google Patents

Abstract

PURPOSE:To attain filtering processing to a hue picture data by projecting the hue picture data from a color picture signal onto a complex number plane and applying filtering processing to the hue picture data projecting onto the complex number plane with a desired band characteristic. CONSTITUTION:A red signal R, a green signal G and a blue signal B are outputted separately from a color picture signal source 10 and monochroic signals R, G, B are converted into a hue picture data H, a lightness picture data L and a saturation picture data S by an HLS conversion means 20. Since the hue picture data H has a discontinuous point, direct filtering processing by digital filters 51, 52 is disabled, Thus, complex number conversion means 41, 42 projecting the hue picture data onto the complex number plane are provided to the output side of the hue picture memory 30A. Thus, the hue picture data subjected to filtering processing is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a color image signal processing method that can be used, for example, when inspecting a color image sensor made of a semiconductor.

"Prior Art" Image sensors made of semiconductors are made using integrated circuit technology, but various defects occur due to defects in the manufacturing process. In particular, when assembled as a color image sensor, defects in the image sensor may cause shading as shown in FIG.
Color unevenness such as diagonal stripes shown in FIG. 5 and vertical stripes shown in FIG. 6 occurs.

In other words, the shading shown in FIG. 3 refers to color unevenness in which a wide area (indicated by reference numeral 1) of the screen, which is supposed to be white, is colored.

The diagonal stripes shown in FIGS. 4 and 5 refer to a phenomenon in which diagonal colored stripes 2 and 3 appear on an otherwise white screen.

Further, the vertical stripes shown in FIG. 5 refer to a phenomenon in which stripes 4 occur in the vertical direction.

Conventionally, color imaging signals were projected onto a color cathode ray tube,
This screen is visually monitored and detected.

It has been found that when visually detecting color unevenness caused by a color image sensor as described above, removing noise components from the image signal makes the color unevenness easier to see. The reason for this is that noise contained in the imaging signal erases part of the hue image data, brightness image data, and saturation image data that represent the presence of color unevenness, and data is missing at the periphery of the area where the striped pattern should be drawn. As a result, the outline of the stripes cannot be clearly seen, and the center and peripheral parts of the stripes, which appear as uneven color, are difficult to see.

Therefore, when the noise component is removed from the color image data, the outline and center of the striped pattern that appears as color unevenness becomes clearly visible, and there is an advantage that the detection accuracy of color unevenness can be improved.

"Problem to be solved by the invention" Digitized color image signals are generally RlG,
It is converted into a B monochromatic signal. In the R, G, B color space, hue, brightness, and saturation information are not independent, so R, G,
When applying various filters such as a band pass filter to the 8 image data, information other than the one being focused on also changes, resulting in the disadvantage that the desired image cannot be obtained.

In order to solve this problem, the color image data has a hue of H11 degrees and a saturation of S (or H, S).

Convert the image data H to
, L, and S, or a method of filtering all of them independently is being considered.

However, as shown in Figure 2, the hue space that expresses color types in terms of angles represents the same red color as 0 degrees and 360 degrees, so
There is a discontinuity between the 0 degree and 360 degree points, and there is a disadvantage that a digital filter cannot be applied.

An object of the present invention is to propose a color image signal processing method capable of filtering hue image data having such characteristics.

"11! Means for Solving the Problem" In the first invention of this application, hue image data is obtained from a color image signal, this hue image data is projected onto a complex plane, and the hue image data projected onto the complex plane is We propose a color image signal processing method that performs filtering processing using desired band characteristics.

According to the present invention, discontinuous points are eliminated by projecting the hue image data onto a complex plane, thereby making it possible to perform filtering processing.

Therefore, filtered hue image data can be obtained.

In the second invention of this application, a color image signal is converted into hue image data, brightness image data, and saturation image data, and the hue image data is subjected to filtering processing according to desired band characteristics, and the filtered hue image A color image signal processing method that calculates the arctangent of the real part and imaginary part of data, converts it back to the original hue image data, and obtains a color image signal from this hue image data and the above-mentioned brightness image data and chroma image data. propose.

According to the second invention, since at least the hue image data of the reproduced color image signal has been filtered, the influence of noise has been removed from the hue image data. The outline and center of the striped pattern representing the color becomes clear, and color unevenness can be easily detected.

"Example" The color image signal processing method proposed in the first and second inventions of this application will be explained using FIG.

Reference numeral 10 shown in FIG. 1 indicates a color image signal source.

A red signal R, a green signal G from this color image signal source lO
, blue signal B are output separately.

Each monochromatic signal R, G output from the color image signal source 10
, B are the hue image data H and the brightness image data L by the well-known (7) HLS conversion means (or H8V conversion means) 20.
and chroma image data S.

The hue image data H, brightness image data L, and saturation image data S obtained by HLS conversion in the conversion means 20 are stored in the hue image memory 30A and the brightness image memory 30, respectively.
B and chroma image memory 30C, respectively.

Hue image data H is obtained as an angle θ with a value of 0 to 360. The relationship between the names of six colors and the angle is 0 to 30.3 for red.
30-360, yellow 30-90, green 90-150, cyan 150-210, blue 210-2701, and magenta 270-330.

The brightness is obtained as a numerical value in the brightness image memory 30B, and the vividness of the color is obtained as a numerical value in the chroma image memory 30C.

The brightness image data L and the saturation image data S are stored in the memory 30B,
30C directly or as required through digital filters 53 and 54 as shown in the figure.
It can be sent to 0.

On the other hand, the hue image data H cannot be directly filtered by the digital filters 51 and 52 because it has discontinuous points as described above.

For this reason, in the present invention, a complex conversion means 4 for projecting hue image data H onto a complex plane is provided on the output side of the hue image memory 30A.
1 and 42 are provided.

The complex conversion means 41 indicates a part that projects the vector represented by hue image data hue (t, j) onto the real part,
Reference numeral 42 indicates a portion that projects the vector represented by hue (i, j) onto the imaginary part.

Specifically, set θ = hue (i, j), take the cosine and sine of θ, and create the complex plane realhue (i, j), im
project each to aginaryhue(i, J).

tealhue(i,j) and is+aginaryhu
e(i,j) is an image having a real number value between -1.0 and 1.0, and stores Hue image information.

realhue (i, j) and im projected on the complex plane
aginaryhue(i+j) is data from which discontinuities have been removed.

This data is applied to digital filters 51 and 52, and R
EALHUE(i,j) and IMG INARYIIUE
(i, get D.

REALI obtained from digital filters 51 and 52
ItlE (i, j) and I MG INARYH
llE(j, j) is given to the inverse complex transformation means 60.

The inverse complex transformation means 60 converts REALHUII! (i, j)
and RTIIET IMAGINARYHUE(i,j)
A=REALHUE(i,j)ITHETA=IMA
GINARYHLIE! (i, j), (IT)I
I! Find the arctangent of TA/RTHHTA).

The image data HU [! (i, j
) is filtered hue image data.

Hue image data HUE obtained from the inverse complex transformation means 60
(i, j) is converted into brightness image data and is supplied to the inverse HLS conversion means 70 together with the chroma image data S, and the inverse HLS conversion means 7
Inverse HLS conversion means 7 by performing inverse HLS conversion with 0
0 to color image signals R, G.

You can get B.

A color image can be displayed using the color image signals R, G, and B.

Effects of the Invention As described above, according to the present invention, it is now possible to apply filtering to the hue image data H, which conventionally could not be subjected to filtering due to discontinuities. The three converted image data H, L, and S could be filtered separately.

Therefore, it is possible to filter hue, brightness, and saturation without interfering with each other, so by arbitrarily setting the band characteristics of each filtering process, you can create a desired image, for example, an image with color unevenness emphasized. This has the advantage that color imaging devices and the like can be easily inspected.

[Brief explanation of drawings]

Figure 1 is a block diagram for explaining the color image signal processing method of the present invention, Figure 2 is a diagram for explaining the state of this hue space, and Figures 3 to 6 are for explaining types of color unevenness. FIG. 1 (l color image signal source, 20: HLS conversion means, 30
A=Hue image copying memory, 30B: Brightness image memory, 30C
: Saturation image memory, 41.42: Complex conversion means, 51~
54: Filter, 6o: Inverse complex transformation means, 70: Inverse HL
Si exchange means.

Claims (2)

[Claims] (1) A color image signal in which hue image data is obtained from a color image signal, this hue image data is projected onto a complex plane, and the hue image data projected onto the complex plane is filtered using desired band characteristics. Processing method. (2) Convert the color image signal into hue image data, brightness image data, and saturation image data, project the hue image data onto a complex plane, and convert the hue image data on the complex plane into desired band characteristics. Then, the arc tangent of the real part and imaginary part of the filtered hue image data is calculated and converted back to the original hue image data. A color image signal processing method for obtaining a color image signal.