JPH04354270A - Automatic gamma controller for luminance signal - Google Patents

Abstract

PURPOSE:To enable a viewer to watch a video image at an optimum gamma correction amount corresponding to a video state. CONSTITUTION:An output from a video luminance signal distribution detection circuit 6 comparaing the ratio of signals detected from both a circuit 4 detecting a luminance signal having 50IRE or more of a video signal and a circuit 5 detecting the luminance signal having less than 50IRE, the output from an APL detection circuit 7 detecting the average luminance level of the video signal, the output from a white area detection circuit 8 detecting the white area of the video signal, the output from a black area detection circuit 9 detecting the black area of the video signal, and the output from a white peak detection circuit 10 detecting the minimum value of the luminance signal are evaluated as fuzzy set, a fuzzy gamma control output is calculated by the fuzzy inference, and the automatic control of a gamma control circuit 1 of the optimum luminance signal is performed by a fuzzy gamma control output.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to automatic control of a gamma control circuit for a luminance signal, and in particular to improved distribution of luminance signals of 50 IRE or more and luminance signals of 50 IRE or less of a video signal, and the average of the video signal. The present invention relates to a device that automatically controls a gamma control circuit according to a brightness level, a white area of a video signal, a black area of a video signal, and a maximum value of a brightness signal.

0002

BACKGROUND OF THE INVENTION In recent years, television screens have become larger at a remarkable rate, and as a result, demands regarding image quality are increasing. In particular, the gradation of the luminance signal has a great influence on the contrast of image quality.

FIG. 3 shows a conventional gamma control device, in which 1 is a gamma control circuit that performs gamma control on a luminance signal, and 2 controls the gamma correction amount by controlling the control level of the gamma control circuit 1. It is a circuit that controls
3 is a Video Chroma Jungle IC.

In the conventional gamma control circuit configured as described above, the gamma correction amount of the first gamma control circuit is adjusted by adjusting the volume of the second gamma control circuit adjustment circuit from the outside.

[0005]

[Problem to be Solved by the Invention] However, in the above configuration, if the gamma control amount is uniquely determined during adjustment at the factory, the control amount of the gamma control circuit is fixed at that set value. However, it has been impossible for viewers to watch television with the optimum amount of gamma correction depending on the constantly changing image conditions.

[0006] In view of this point, the present invention of an automatic gamma control device for luminance signals is aimed at enabling a viewer to view a television with an optimum amount of gamma correction depending on the video.

[0007]

[Means for Solving the Problems] In order to solve the above problems, an automatic control device for a gamma control circuit for a luminance signal according to the present invention includes a gamma control circuit capable of gamma-controlling a luminance signal for a video signal, and a 50 IRE control circuit for a video signal. A circuit that detects the above luminance signals, a circuit that detects luminance signals of 50 IRE or less, a video luminance signal distribution detection circuit that compares the proportions of those detected signals, and A that detects the average luminance level of the video signal.
A PL detection circuit, a white area detection circuit that detects a white area of a video signal, a black area detection circuit that detects a black area of a video signal, a white peak detection circuit that detects a maximum value of a luminance signal,
preprocessing means for creating a control index for evaluating the output of the video luminance signal distribution detection circuit as a fuzzy set;
a preprocessing means for creating a control index for evaluating the output of the APL detection circuit as a fuzzy set; a preprocessing means for creating a control index for evaluating the output of the white area detection circuit as a fuzzy set; a preprocessing means for creating a control index for evaluating the output of the black area detection circuit as a fuzzy set; a preprocessing means for creating a control index for evaluating the output of the white peak detection circuit as a fuzzy set; An output from a preprocessing means for creating a control index for evaluating the output of the video luminance signal distribution detection circuit as a fuzzy set, and a preprocessing means for creating a control index for evaluating the output of the APL detection circuit as a fuzzy set. Creating a control index for evaluating the output from the preprocessing means and the output of the white area detection circuit as a fuzzy set.Creating a control index for evaluating the output from the preprocessing means and the output of the black area detection circuit as a fuzzy set. Fuzzy inference means performs respective fuzzy inferences by inputting the output from the preprocessing means for generating a control index for evaluating the output from the white peak detection circuit as a fuzzy set, and the output from the preprocessing means for creating a control index for evaluating the output from the white peak detection circuit as a fuzzy set; fuzzy gamma control output determining means for determining a fuzzy gamma control output using the output of the inference means as input; and gamma control amount correction for controlling the control amount of the gamma control circuit in accordance with the control output of the fuzzy gamma control output determining means. This is an automatic control device for a gamma control circuit for a luminance signal, characterized in that it is equipped with a circuit.

[0008]

[Operation] With the above-described configuration, the present invention provides 50% of the video signal.
A circuit that detects a luminance signal higher than IRE and 50IRE
An output from a video brightness signal distribution detection circuit that compares the proportions of the signals detected by the circuit that detects the following brightness signals, an output from an APL detection circuit that detects the average brightness level of the video signal, and a video signal. Fuzzy set of the output from the white area detection circuit that detects the white area of the video signal, the output from the black area detection circuit that detects the black area of the video signal, and the output from the white peak detection circuit that detects the maximum value of the luminance signal. A fuzzy gamma control output is calculated by fuzzy inference, and the gamma control circuit of the optimal luminance signal is automatically controlled using this fuzzy gamma control output.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the structure of an automatic control device for a luminance signal gamma control circuit according to a first embodiment of the present invention. In FIG. 1, 1 is a gamma control device for luminance signals, and 2 is a circuit that controls the amount of gamma correction by controlling the control level of the gamma control circuit 1. In FIG. FIG. 14 is a graph showing the characteristics when gamma correction is applied to the luminance signal. 1 is the characteristic curve when gamma correction is applied, 2 is the characteristic curve when inverse gamma correction is applied, and 3 is the characteristic curve when no correction is applied. do. 3 is the Video Chroma Jungle IC,
4 is a circuit that detects a luminance signal of 50 IRE or more of a video signal, 5 is a circuit that detects a luminance signal of 50 IRE or less of a video signal, and 6 is a circuit that detects a luminance signal of 50 IRE or more of a video signal.
This is a circuit that detects the distribution state of the video luminance signal by comparing the signal of RE or more with the signal of 50 IRE or less detected by the circuit 5, and 7 is an AP that detects the average brightness level of the video signal.
8 is a white area detection circuit for detecting the white area of the video signal, 9 is a black area detection circuit for detecting the black area of the video signal, and 10 is for detecting the maximum value of the luminance signal. This is a white peak detection circuit, and 11 is a fuzzy gamma control device which inputs the outputs from the detection circuit 6 to the detection circuit 10 and fuzzy infers the optimum gamma control amount.

FIG. 2 is a detailed diagram of the fuzzy gamma control device 11 in FIG. 1. The fuzzy gamma control device obtains the detected values from the detection circuits 6 to 10, and receives the detected values from the preprocessing devices 12 to 1.
In step 6, a control index value for evaluating the fuzzy set is created. The fuzzy inference devices 17 to 21 perform fuzzy inference using the control index values from the preprocessing devices 12 to 16 as input. The outputs from the fuzzy inference devices 17 to 21 are given to a fuzzy gamma control output determining device 22,
Here, the fuzzy gamma control output as the output of the fuzzy gamma control device 11 is determined. The output from the fuzzy gamma control device 11 is input to a gamma control amount correction circuit 2 that corrects the gamma correction amount of the gamma control circuit 1. Then, the gamma control amount correction circuit 2 controls the gamma correction amount applied to the luminance signal of the gamma control circuit 1 to always maintain optimal gamma control.

The automatic control of the luminance signal gamma control circuit configured as described above will be explained below. First, the detection circuit 4 in FIG. 1 detects what percentage of one screen is 50 IRE or more, and the detected result is converted into a voltage. Next, in the detection circuit 5, similar to the detection circuit 4, what percentage of one screen is 5?
It is detected whether it is less than 0IRE and the result is converted into a voltage. The reason why the detection circuit 4 and the detection circuit 5 perform similar processing is to improve detection accuracy. Next, the detection circuit 6 compares the output of the detection circuit 4 and the output of the detection circuit 5 to detect the distribution state of the video luminance signal. Note that the detection circuit 4 and the detection circuit 5 are preferably set at appropriate slice levels depending on the performance of the gamma control circuit 1. Next, the average luminance level is detected in the detection circuit 7 and the result is converted into a voltage. Next, the detection circuit 8 detects a white area that has a brightness above a certain level and is not covered by a color signal, and converts the result into a voltage. Next, the detection circuit 9 detects a black area with a brightness below a certain level and no color signal, and converts the result into a voltage. Note that in the detection circuits 8 and 9, it is preferable to set appropriate slice levels according to the performance of the gamma circuit 1, similarly to the detection circuits 3 and 4. Next, the detection circuit 10 detects the maximum value of the luminance signal and converts the result into a voltage. It goes without saying that the output of the detection circuit may be not only voltage but also current.

Each detection value detected in this way is shown in FIG.
input to each preprocessing device from 12 to 16 in
A control index for evaluation as a fuzzy set is created in each of the preprocessing devices 12 to 16. Figure 4
is a membership function used in the preprocessing device 12 of FIG. 2 which inputs the output from the circuit 6 for detecting the distribution state of the video luminance signal of FIG. 1. FIG. 5 shows membership functions used in the preprocessing device 13 of FIG. 2, which receives the output from the APL detection circuit 7 for detecting the average luminance level of the video signal of FIG. 1. FIG. 6 shows membership functions used in the preprocessing device 14 of FIG. 2, which receives the output from the white area detection circuit 8 for detecting the white area of the video signal of FIG. 1. FIG. 7 shows membership functions used in the preprocessing device 15 of FIG. 2, which receives the output from the black area detection circuit 9 for detecting the black area of the video signal of FIG. 1. FIG. 8 shows the preprocessing device 16 in FIG. 2 that receives the output from the white peak detection circuit 10 that detects the maximum value of the luminance signal in FIG. 1.
This is the membership function used in .

FIG. 9 shows a control rule representing the relationship between the luminance signal distribution state and the gamma correction amount. FIG. 10 shows a control rule representing the relationship between the average brightness level and the gamma correction amount. Figure 11
is a control rule expressing the relationship between the white area of the video signal and the gamma correction amount. FIG. 12 shows a control rule representing the relationship between the black area of the video signal and the amount of gamma correction. FIG. 13 shows a control rule representing the relationship between the maximum value of the luminance signal and the amount of gamma correction.

The fuzzy inference method using the fuzzy inference device shown in 17 to 21 in FIG. A method is used in which a fuzzy operation is performed along , a synthetic fuzzy set is calculated, the maximum value of this synthetic fuzzy set is set as an output synthetic function, and the center of gravity of this output synthetic function is the output of fuzzy inference. Needless to say, this can be done not only by the center of gravity method but also by the height method or other output value calculation methods.

Fuzzy gamma control output determination device 2 in FIG.
2, the final gamma control correction amount is calculated by arithmetic averaging by inputting the outputs from each of the fuzzy inference devices 17 to 21 of FIG. 2 obtained according to the above-described inference method, The gamma control circuit 1 is controlled through. It goes without saying that not only the arithmetic mean but also the centroid method, height method, and other calculation methods may be used.

As described above, according to this embodiment, by detecting the distribution state of the luminance signal, the average luminance level, the white area of the video signal, the black area of the video signal, or the maximum value of the luminance signal, Optimal gamma correction control can be performed depending on the image state at that time.

[0017]

As described above, the present invention provides a gamma control circuit that can gamma control the luminance signal of a video signal, a circuit that detects a luminance signal of 50 IRE or more of a video signal, and
A circuit that detects the following luminance signals, a video luminance signal distribution detection circuit that compares the proportions of those detected signals, an APL detection circuit that detects the average luminance level of the video signal, and a white area of the video signal. A white area detection circuit, a black area detection circuit that detects the black area of the video signal, a white peak detection circuit that detects the maximum value of the video signal, and the output of the video luminance signal distribution detection circuit for evaluating as a fuzzy set. preprocessing means for creating a control index for evaluating the output of the APL detection circuit as a fuzzy set; and preprocessing means for creating a control index for evaluating the output of the white area detection circuit as a fuzzy set. preprocessing means for creating a control index; preprocessing means for creating a control index for evaluating the output of the black area detection circuit as a fuzzy set; and preprocessing means for creating a control index for evaluating the output of the white peak detection circuit as a fuzzy set. Pre-processing means for creating a control index; output from the pre-processing means for creating a control index for evaluating the output of the video luminance signal distribution detection circuit as a fuzzy set; and evaluating the output of the APL detection circuit as a fuzzy set. The output from the preprocessing means for creating a control index for evaluating the output of the white area detection circuit as a fuzzy set, and the output from the black area detection circuit for evaluating the output of the white area detection circuit as a fuzzy set. The output from the preprocessing means for creating a control index for evaluating the output of the white peak detection circuit as a fuzzy set and the output from the preprocessing means for creating a control index for evaluating the output of the white peak detection circuit as a fuzzy set are input. fuzzy inference means for performing fuzzy inference; fuzzy gamma control output determining means for determining a fuzzy gamma control output using the output of the fuzzy inference means as input; and the gamma control circuit according to the control output of the fuzzy gamma control output determining means. By providing a gamma control amount correction circuit that controls the control amount, it is possible for the viewer to view the video with optimal gamma correction according to the video condition, which has a great practical effect.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an automatic gamma control device for luminance signals in a first embodiment of the present invention.

[Figure 2] Detailed block diagram of arithmetic and control unit

[Figure 3] Block diagram of conventional gamma control device

[Figure 4] Characteristic diagram showing the relationship between the distribution state of the luminance signal and the amount of gamma correction

[Figure 5] Characteristic diagram showing the relationship between average brightness level and gamma correction amount

[Figure 6] Characteristic diagram showing the relationship between the white area of the video signal and the amount of gamma correction

[Figure 7] Characteristic diagram showing the relationship between the black area of the video signal and the amount of gamma correction

[Figure 8] Characteristic diagram showing the relationship between the maximum value of the luminance signal and the amount of gamma correction

[Fig. 9] A diagram showing a control rule representing the relationship between the luminance signal distribution state and the gamma correction amount.

[Fig. 10] A diagram showing a control rule representing the relationship between average brightness level and gamma correction amount.

[Fig. 11] A diagram showing a control rule representing the relationship between the white area of a video signal and the amount of gamma correction.

[Fig. 12] A diagram showing a control rule representing the relationship between the black area of a video signal and the amount of gamma correction.

[Fig. 13] A diagram showing a control rule representing the relationship between the maximum value of the luminance signal and the amount of gamma correction.

[Figure 14] Graph showing the characteristics when gamma correction is applied to the luminance signal

[Explanation of symbols]

1 Gamma control circuit 2 Gamma correction amount control device 3 Video chroma jungle 4 Luminance signal detection circuit of 50IRE or more 5 50I
Luminance signal detection circuit below RE 6 Luminance signal distribution state detection circuit 7 APL detection circuit 8 White area detection circuit 9 Black area detection circuit 10 White peak detection circuit 11 Fuzzy gamma control device

Claims (6)

[Claims] 1. A gamma control circuit capable of gamma-controlling a luminance signal of a video signal, a circuit for detecting a luminance signal of 50 IRE or more of a video signal, a circuit for detecting a luminance signal of 50 IRE or less, and a ratio of these detected signals. a video luminance signal distribution detection circuit for comparing the video luminance signal distribution detection circuit; a preprocessing means for creating a control index for evaluating the output of the video luminance signal distribution detection circuit as a fuzzy set; and a fuzzy inference using the output of the preprocessing means as input. fuzzy gamma control output determining means for determining a fuzzy gamma control output using the output of the fuzzy inference means as input; and a control amount of the gamma control circuit according to the control output of the fuzzy gamma control output determining means. Automatic gamma of a luminance signal, characterized in that the gamma control circuit is equipped with a gamma control amount correction circuit that performs control, and performs fuzzy control of the gamma control circuit according to the distribution state of a luminance signal of 50 IRE or more and a luminance signal of 50 IRE or less of a video signal. Control device. 2. A gamma control circuit capable of gamma-controlling a luminance signal of a video signal, an APL detection circuit detecting an average luminance level of the video signal, and a control index for evaluating the output of the APL detection circuit as a fuzzy set. fuzzy inference means for performing fuzzy inference using the output of the preprocessing means as input; fuzzy gamma control output determining means for determining a fuzzy gamma control output using the output of the fuzzy inference means as input; A gamma control amount correction circuit is provided for controlling the control amount of the gamma control circuit in accordance with the control output of the fuzzy gamma control output determining means, and the gamma control circuit is fuzzy controlled in accordance with the average luminance level of the video signal. Features an automatic gamma control device for luminance signals. 3. A gamma control circuit that can perform gamma control on a luminance signal of a video signal, a white area detection circuit that detects a white area of the video signal, and a control index for evaluating the output of the white area detection circuit as a fuzzy set. a preprocessing means for creating;
fuzzy inference means for performing fuzzy inference using the output of the preprocessing means as input; fuzzy gamma control output determining means for determining a fuzzy gamma control output using the output of the fuzzy inference means as input; Automatic gamma of a luminance signal, comprising a gamma control amount correction circuit that controls the control amount of the gamma control circuit according to a control output, and fuzzy control of the gamma control circuit according to a white area of a video signal. Control device. 4. A gamma control circuit capable of gamma-controlling a luminance signal of a video signal, a black area detection circuit detecting a black area of the video signal, and a control index for evaluating the output of the black area detection circuit as a fuzzy set. a preprocessing means for creating;
fuzzy inference means for performing fuzzy inference using the output of the preprocessing means as input; fuzzy gamma control output determining means for determining a fuzzy gamma control output using the output of the fuzzy inference means as input; Automatic gamma for luminance signals, comprising a gamma control amount correction circuit that controls the control amount of the gamma control circuit in accordance with a control output, and fuzzy control of the gamma control circuit in accordance with a black area of a video signal. Control device. 5. A gamma control circuit capable of gamma-controlling a luminance signal of a video signal, a white peak detection circuit detecting a maximum value of the luminance signal, and a control index for evaluating the output of the white peak detection circuit as a fuzzy set. fuzzy inference means for performing fuzzy inference using the output of the preprocessing means as input; fuzzy gamma control output determining means for determining a fuzzy gamma control output using the output of the fuzzy inference means as input; A gamma control amount correction circuit is provided for controlling a control amount of the gamma control circuit in accordance with a control output of the fuzzy gamma control output determining means, and the gamma control circuit is fuzzy controlled in accordance with a maximum value of the luminance signal. Features an automatic gamma control device for luminance signals. 6. A gamma control circuit capable of gamma controlling a luminance signal of a video signal, and a 50I of the video signal according to claim 1.
A circuit for detecting a luminance signal of 50 IRE or more, a circuit for detecting a luminance signal of 50 IRE or less, a video luminance signal distribution detection circuit for comparing the proportions of these detected signals, and an average luminance of the video signal according to claim 2. an APL detection circuit for detecting the level; a white area detection circuit for detecting the white area of the video signal according to claim 3; a black area detection circuit for detecting the black area of the video signal according to claim 4; A white peak detection circuit for detecting the maximum value of the luminance signal according to claim 5, a preprocessing means for creating a control index for evaluating the output of the video luminance signal distribution detection circuit as a fuzzy set, and the APL detection circuit. preprocessing means for creating a control index for evaluating the output of the white area detection circuit as a fuzzy set, preprocessing means for creating a control index for evaluating the output of the white area detection circuit as a fuzzy set, and the black area detection circuit preprocessing means for creating a control index for evaluating the output of the white peak detection circuit as a fuzzy set; preprocessing means for creating a control index for evaluating the output of the white peak detection circuit as a fuzzy set; and the video luminance signal distribution. An output from a preprocessing means for creating a control index for evaluating the output of the detection circuit as a fuzzy set; and an output from the preprocessing means for creating a control index for evaluating the output of the APL detection circuit as a fuzzy set; An output from a preprocessing means for creating a control index for evaluating the output of the white area detection circuit as a fuzzy set, and a preprocessing means for creating a control index for evaluating the output of the black area detection circuit as a fuzzy set. Fuzzy inference means performs fuzzy inference using the output from the preprocessing means for creating a control index for evaluating the output of the white peak detection circuit and the output of the white peak detection circuit as a fuzzy set as input, and the output of the fuzzy inference means. fuzzy gamma control output determining means for determining a fuzzy gamma control output by inputting the fuzzy gamma control output determining means; and a gamma control amount correction circuit for controlling a control amount of the gamma control circuit in accordance with the control output of the fuzzy gamma control output determining means. , a luminance signal of 50 IRE or more of the video signal and 50
A luminance signal characterized in that a gamma control circuit is fuzzy controlled according to a distribution state of a luminance signal below IRE, an average luminance level of a video signal, a white area of the video signal, a black area of the video signal, and a maximum value of the luminance signal. automatic gamma control device.