JP2003153037A - Contour correcting circuit for video signal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable to view a video image in an optimal state of reproducing a skin color. SOLUTION: The circuit consists of a skin color area detecting circuit 1 for detecting an area of a skin color portion in one frame from a color difference signal, a skin color average luminance level detecting circuit 2 for detecting an average luminance level of the skin color portion in one frame from the color difference signal and a luminance signal, an average luminance level detecting circuit 3 for detecting an average luminance level of one frame from the luminance signal, a skin color correcting circuit 4 for forming a skin color correcting signal by using the outputs from the circuits 1, 2 and 3 as an input, a color difference contour correcting circuit 5 for multiplying the color difference signal by a color difference contour correction according to the skin color correcting signal, and a luminance contour correcting circuit 6 for multiplying the luminance signal of a video signal by a contour correction according to the skin color correcting signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of reproduction of a flesh color signal of a video signal, and particularly to an improved area of a flesh color portion of a video signal, an average luminance level of a flesh color portion of a video signal, and an average luminance of a video signal. The present invention relates to a circuit for improving reproduction of a skin color signal of a video signal according to a level.

[0002]

2. Description of the Related Art In recent years, there has been a remarkable increase in the screen size of televisions, and therefore the demand for image quality is increasing. In particular, the human eye is sensitive to reproduction of human skin, and the reproducibility of human skin has a great influence on image quality.

A conventional skin color correction circuit is disclosed in Japanese Patent Laid-Open No. 2001-10.
The one described in 3504 is known.

FIG. 4 shows a block diagram of a conventional skin color luminance improving circuit. R, G, B signals are created from the luminance signal Y and the color difference signals U, V input by the matrix circuit 14, and R
The GB ratio detection circuit 20 detects the level ratio of the R, G, B signals, and the skin color correction unit in the color correction circuit 22 performs the skin color correction processing on the input R, G, B signals, and the I axis detection circuit and the Q axis. Perform the detection circuit.

Further, the gamma correction circuit 24 has a logarithmic operation unit,
A first multiplication unit and an exponent calculation unit are provided, the logarithmic calculation unit performs logarithmic calculation processing on the input R, G, and B signals, and the first multiplication unit multiplies the output of the logarithmic calculation unit by a gamma constant γ to perform exponential calculation. Part performs exponential calculation processing on the output of the first multiplication part, and the gamma constant γ can be set and changed to arbitrarily change the gamma correction curve.

[0006]

However, although the gamma correction is possible in the above-mentioned configuration,
The outline portion, which is another factor that determines the image quality, is not corrected, and it cannot be said that it is the optimum skin color correction.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a video signal contour correction circuit that enables a viewer to watch a television in an optimum skin color reproduction state according to a video state.

[0008]

In order to solve the above problems, the flesh color reproduction circuit of the present invention uses a color difference signal of a video signal to
A skin color area detection circuit for detecting the area of the skin color portion in the frame, a skin color average luminance level detection circuit for detecting the average luminance level of the skin color portion in one frame from the color difference signal and the luminance signal of the video signal, and the luminance of the video signal. An average brightness level detection circuit for detecting the average brightness level of one frame from the signal;
With the output from the skin color area detection circuit, the output from the skin color average luminance level detection circuit, and the output from the average luminance level detection circuit as input, the area of the skin color portion of one frame and the average luminance level of the skin color portion of one frame are set. A flesh color correction circuit that creates a flesh color correction signal according to the average luminance level of one frame, and an output from the flesh color correction circuit is input to apply color difference contour correction according to the flesh color correction signal to the flesh color portion of the color difference signal of the video signal. The color difference contour correction circuit and the luminance contour correction circuit that receives the output from the flesh color correction circuit and applies contour correction according to the flesh color correction signal to the flesh color portion of the luminance signal of the video signal are provided.

According to the present invention having the above-mentioned structure, a skin color area detecting circuit for detecting the area of the skin color portion in one frame from the color difference signal of the video signal, and the skin color area of one frame from the color difference signal and the luminance signal of the video signal. The flesh color correction circuit calculates the output from the flesh color average luminance level detection circuit that detects the average luminance level and the average luminance level detection circuit that detects the average luminance level of one frame from the luminance signal of the video signal to calculate the video state. A flesh color correction signal is generated in the flesh color correction circuit according to the input signal representing the image state, and the contour signal is corrected to an optimum flesh color according to the state of the image signal by the output signal from the flesh color correction circuit.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) FIG. 1 shows the configuration of a skin color reproduction circuit according to an embodiment of the present invention. In FIG. 1, reference numeral 1 is a skin color area detection circuit for detecting the area of the skin color portion in one frame from the color difference signal of the video signal, and 3 is an average luminance level for detecting the average luminance level of one frame from the luminance signal of the video signal. It is a detection circuit.

Reference numeral 4 designates the area of the skin color portion of one frame and the skin color portion of one frame with the output from the skin color area detection circuit, the output from the skin color average luminance level detection circuit and the output from the average luminance level detection circuit as inputs. 2 is a skin color correction circuit that creates a skin color correction signal according to the average brightness level of 1 and the average brightness level of one frame.

Reference numeral 5 denotes a color difference contour correction circuit which receives the output from the skin color correction circuit and applies color difference contour correction according to the skin color correction signal to the skin color portion of the color difference signal of the video signal.

Reference numeral 6 is a luminance contour correction circuit which receives the output from the flesh color correction circuit and applies contour correction according to the flesh color correction signal to the flesh color portion of the luminance signal of the video signal.

The operation of the flesh color reproduction circuit configured as described above will be described below. First, the skin color area detection circuit 1 in FIG. 1 detects the area of the skin color portion in one frame from the color difference signal of the video signal and converts the detected result into a voltage.

Next, the average luminance level detection circuit 3 detects the average luminance level of one frame from the luminance signal of the video signal and converts the detected result into a voltage. It goes without saying that the output of the detection circuit may be not only voltage but also current or digital data.

The detected values thus detected are shown in FIG.
The flesh color correction circuit 4 inputs the flesh color correction signal in accordance with the area of the flesh color portion of one frame and the average luminance level of one frame, converts it into voltage or current or digital data, and outputs it.

The output flesh color correction signal is first input to the color difference contour correction circuit 5, and color difference contour correction according to the flesh color correction signal is applied to the flesh color portion of the color difference signal of the video signal.

Next, the flesh color correction signal is the luminance signal correction circuit 6
The contour correction corresponding to the skin color correction signal is applied to the skin color portion of the luminance signal of the video signal.

As described above, according to the present embodiment, by detecting the area of the flesh color portion of one frame and the average luminance level of one frame, the contour to the optimal flesh color corresponding to the flesh color area and the average luminance level of the image is obtained. Correction is possible.

(Embodiment 2) FIG. 2 shows the configuration of a skin color reproduction circuit according to an embodiment of the present invention. In FIG. 2, the structure is different from that of the first embodiment in that the skin color area detection circuit 1 is replaced with a skin color average luminance level detection circuit 2.

The skin color average luminance level detection circuit 2 detects the average luminance level of the skin color portion in one frame from the color difference signal and the luminance signal of the video signal. Example 1 is applied to other configurations.
The description is omitted because it is the same as.

The operation of the skin color reproduction circuit configured as described above will be described below. First, the skin color average brightness level detection circuit 2 in FIG. 2 detects the average brightness level of the skin color portion in one frame from the color difference signal and the brightness signal of the video signal, and converts the detected result into a voltage.

Next, the average luminance level detection circuit 3 detects the average luminance level of one frame from the luminance signal of the video signal and converts the detected result into a voltage. It goes without saying that the output of the detection circuit may be not only voltage but also current or digital data.

The detected values thus detected are shown in FIG.
The flesh color correction circuit 4 inputs the flesh color correction signal according to the average luminance level of the flesh color portion of one frame and the average luminance level of one frame, converts it into voltage or current or digital data, and outputs it. The output flesh color correction signal is first input to the color difference contour correction circuit 5, and color difference contour correction according to the flesh color correction signal is applied to the flesh color portion of the color difference signal of the video signal.

Next, the flesh color correction signal is the brightness contour correction circuit 6
Signal correction is applied to the flesh color portion of the luminance signal of the video signal.

As described above, according to the present embodiment, by detecting the average luminance level of the flesh color portion of one frame and the average luminance level of one frame, the optimum flesh color luminance level and the average luminance level of the image can be optimized. It is possible to correct the contour to the skin color.

(Third Embodiment) FIG. 3 shows a configuration of a skin color reproduction circuit according to an embodiment of the present invention. In FIG. 3, the configuration is different from that of the first embodiment described above in that the skin color average luminance level detection circuit 2 used in the second embodiment is added. The other configurations are similar to those of the first embodiment, and thus the description thereof is omitted.

The operation of the flesh color reproduction circuit configured as described above will be described below. First, the skin color area detection circuit 1 in FIG. 3 detects the area of the skin color portion in one frame from the color difference signal of the video signal and converts the detected result into a voltage.

Next, the skin color average brightness level detection circuit 2 detects the average brightness level of the skin color portion in one frame from the color difference signal and the brightness signal of the video signal, and converts the detected result into a voltage.

Next, the average luminance level detection circuit 3 detects the average luminance level of one frame from the luminance signal of the video signal and converts the detected result into a voltage.

It goes without saying that the output of the detection circuit may be not only voltage but also current or digital data.

The detected values thus detected are shown in FIG.
Input to the flesh color correction circuit 4 in 1 to generate a flesh color correction signal according to the area of the flesh color portion of one frame, the average luminance level of the flesh color portion of one frame, and the average luminance level of one frame, and convert it into voltage or current or digital data. Output.

The output flesh color correction signal is first input to the color difference contour correction circuit 5, and color difference contour correction according to the flesh color correction signal is applied to the flesh color portion of the color difference signal of the video signal.

Next, the flesh color correction signal is applied to the luminance signal correction circuit 6
The contour correction corresponding to the skin color correction signal is applied to the skin color portion of the luminance signal of the video signal.

As described above, according to the present embodiment, the state of the skin color of the image and the average of the skin color of the image are detected by detecting the area of the skin color portion of one frame, the average luminance level of the skin color portion of one frame, and the average luminance level of one frame. According to the brightness level, it is possible to perform contour correction to an optimum skin color that reproduces the skin color more beautifully.

[0036]

As described above, according to the present invention, the viewer performs viewing with optimum contour correction according to the average brightness level of the flesh-colored portion of the video signal, the area of the flesh-colored portion of the video signal, and the average luminance level of the video signal. It can be possible, and its practical effect is great.

[Brief description of drawings]

FIG. 1 is a block diagram of a skin color reproduction circuit according to a first embodiment of the present invention.

FIG. 2 is a block configuration diagram of a skin color reproduction circuit according to a second embodiment of the present invention.

FIG. 3 is a block configuration diagram of a skin color reproduction circuit according to a third embodiment of the present invention.

FIG. 4 is a block configuration diagram of a conventional skin color correction circuit.

[Explanation of symbols]

1 Skin color area detection circuit 2 Skin color average brightness level detection circuit 3 Average brightness level detection circuit 4 Skin color correction circuit 5 Color difference contour correction circuit 6 Brightness contour correction circuit 10, 12 Gain control amplifier circuit 14 Matrix circuit 16 Y signal generation circuit 18 Y level judgment circuit 20 RGB ratio detection circuit 22 color correction circuit 24 Gamma correction circuit 26 Display B, B1, B2 green light G, G1, G2 Green traffic light R, R1, R2 red traffic light U, V color difference signal Y luminance signal

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroshi Moribe             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Hisao Morita             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Hitoshi Ando             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Ryuichi Shibuya             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Koji Matsudaira             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 5C021 PA53 PA66 XA06 XB03

Claims (3)

[Claims] 1. A skin color area detection circuit for detecting an area of a skin color portion in one frame from a color difference signal, an average brightness level detection circuit for detecting an average brightness level of one frame from a brightness signal, and the skin color area detection circuit. Input and the output from the average brightness level detection circuit, and a skin color correction circuit that creates a skin color correction signal according to the skin color area of one frame and the average brightness level of one frame, and the output from the skin color correction circuit are input. As a color difference contour correction circuit that applies color difference contour correction according to the skin color correction signal to the skin color portion of the color difference signal,
A luminance contour correction circuit is provided, which receives the output from the flesh color correction circuit and applies contour correction according to the flesh color correction signal to the flesh color portion of the luminance signal, according to the area of the flesh color portion of the video signal and the average luminance level of the video signal. A contour correction circuit for a video signal, which applies luminance contour correction and color difference contour correction to a skin color portion of the video signal. 2. A flesh color average luminance level detection circuit for detecting an average luminance level of a flesh color portion in one frame from the color difference signal and the luminance signal, and an average luminance level detection circuit for detecting an average luminance level of one frame from the luminance signal. , A skin color for which an output from the skin color average brightness level detection circuit and an output from the average brightness level detection circuit are input, and a skin color correction signal is created in accordance with the average brightness level of the skin color part of one frame and the average brightness level of one frame A correction circuit, a color difference contour correction circuit that receives the output from the flesh color correction circuit and applies color difference contour correction according to the flesh color correction signal to the flesh color portion of the color difference signal, and a flesh color correction signal that receives the output from the flesh color correction circuit as input It is equipped with a luminance contour correction circuit that applies signal correction according to the above to the flesh-colored portion of the luminance signal. A contour correction circuit for a video signal, wherein luminance contour correction and color difference contour correction are applied to the flesh color portion of the video signal according to the average luminance level of the signal. 3. A skin color area detecting circuit for detecting an area of a skin color portion in one frame from the color difference signal, and a skin color average luminance level detecting circuit for detecting an average luminance level of the skin color portion in one frame from the color difference signal and the luminance signal. An average brightness level detection circuit for detecting an average brightness level of one frame from a brightness signal; an output from the skin color area detection circuit; an output from the skin color average brightness level detection circuit; and an output from the average brightness level detection circuit. To the skin color correction circuit for creating a skin color correction signal according to the area of the skin color portion of one frame, the average brightness level of the skin color portion of one frame, and the average brightness level of one frame, and the output from the skin color correction circuit. As input, the color difference contour correction circuit for applying the color difference contour correction according to the skin color correction signal to the skin color portion of the color difference signal, and the output from the skin color correction circuit As a result, it is equipped with a brightness contour correction circuit that applies signal correction according to the skin color correction signal to the skin color part of the brightness signal, and determines the average brightness level of the skin color part of the video signal, the area of the skin color part of the video signal and the average brightness level of the video signal. A contour correction circuit for a video signal, which applies luminance contour correction and color difference contour correction to a flesh-colored portion of the video signal accordingly.