JPH077635A - Feedback controller for black extension correction - Google Patents

Abstract

PURPOSE:To feedback control black extension correction and to view a video without black paint-out by optimum black extension correction quantity corresponding to a video state in a television receiver. CONSTITUTION:A black extension correction circuit 1 which can control the black extension correction of a luminance signal, a black extension correction gain control circuit 2 controlling the correction quantity of black extension correction by controlling the gain level of the black extension correction circuit 1, a black level detection circuit 3 for detecting the black level of the luminance signal after black extension correction, a black extension suppression feedback circuit 4 for preventing black paint-out by suppressing the excessive correction of black extension correction and a black extension suppression level adjustment circuit 5 which can arbitrarily set the black extension correction suppression level of the black extension suppression feedback circuit 4 are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a feedback control for black expansion correction of a luminance signal, and in particular, by setting an improved black expansion correction suppression feedback level arbitrarily, a black shadow due to overcorrection of black expansion correction of a video signal. The present invention relates to a feedback control device for black expansion correction of a luminance signal that prevents the above-mentioned problem.

[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 gradation of the luminance signal has a great influence on the contrast of the image quality.

FIG. 2 shows a block diagram of a conventional black expansion correction control device. Reference numeral 1 is a black expansion correction circuit for black expansion correction of the luminance signal, and 2 is a black expansion correction gain control circuit for controlling the correction amount of the black expansion correction by controlling the gain level of the black expansion correction circuit 1. 3 is an IC of video chroma jungle.

In the conventional black expansion correction circuit configured as described above, the black expansion correction amount of the black expansion correction circuit 1 is adjusted by adjusting the volume in the black expansion correction gain control circuit 2 from the outside. adjust.

[0005]

However, in the above configuration, when the black expansion correction amount is uniquely determined during the factory adjustment, the control amount of the black expansion correction circuit is fixed as it is. It

Since the black expansion correction with a fixed gain is always applied to the ever-changing image state, overcorrection of the black expansion is applied to a certain image, and black crushing occurs in which the image information on the black side is compressed.

Further, when the pedestal level of the sending video signal has a setup, the black adjustment signal is not a sufficient black expansion correction amount with the factory adjustment value, so the signal on the black side of the image is not sufficiently drawn to the black side, and there is no tightness in appearance. There was a problem that it became an image.

In view of the above point, the present invention enables viewing with an optimum black expansion correction amount that does not cause underexposure in the image of the television receiver.

[0009]

In order to solve the above problems, a feedback control device for black expansion correction according to the present invention comprises:
A black expansion correction circuit that can control black expansion correction for the luminance signal of the video signal, a black expansion correction gain control circuit that controls the amount of black expansion correction by controlling the gain level of the black expansion correction circuit, and after black expansion correction Level detection circuit for detecting the black level of the luminance signal of the image, a black expansion suppression feedback circuit for preventing black underexposure by suppressing overcorrection of the black expansion correction, and a black expansion correction of the black expansion suppression feedback circuit. The configuration is provided with a black expansion suppression level adjusting circuit that can arbitrarily set the suppression level.

[0010]

According to the present invention, with the above-described structure, the output from the black level detection circuit for detecting the black level of the luminance signal after the black expansion correction and the black expansion suppression level of the black expansion suppression feedback are arbitrarily adjusted. The output from the suppression level adjustment circuit is compared in a black expansion suppression feedback circuit that suppresses overexposure of black expansion correction to prevent black crushing, and black expansion correction is performed based on the black expansion suppression level adjusted in the black expansion suppression feedback circuit. When the black level of the subsequent luminance signal is on the black side, the black expansion correction is suppressed to perform optimum black expansion correction control.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A feedback control device for black expansion correction according to one embodiment of the present invention will be described below with reference to the configuration of FIG.

In FIG. 1, reference numeral 1 is a luminance signal black expansion correction circuit, and 2 is a black expansion correction gain control circuit for controlling the black expansion correction amount by controlling the gain of the black expansion correction circuit 1. Reference numeral 3 is a black level detection circuit for detecting the black level of the luminance signal after black expansion correction, and reference numeral 4 is a black expansion suppression feedback circuit for suppressing black underexposure by suppressing overcorrection of black expansion correction. Reference numeral 5 is a black expansion suppression level adjusting circuit capable of arbitrarily setting the black expansion correction suppression level of the black expansion suppression feedback circuit, and 6 is an IC of the video chroma jungle.

The operation of the black expansion correction feedback control device configured as described above will be described below.

First, the black expansion correction circuit 1 applies black expansion correction to the luminance signal. At this time, the black expansion correction amount is determined according to the control amount given from the black expansion correction gain control circuit 2. The control amount at this time may be a voltage value or a current value.

Next, the black level of the luminance signal after the black expansion correction is detected in the black level detection circuit 3, and the result is sent to the black expansion suppression feedback circuit 4 as a voltage value or a current value.

On the other hand, the feedback level arbitrarily set in the black expansion suppression level adjusting circuit 5 is also expressed as a voltage value or a current value in the black expansion suppression feedback circuit 4.
Sent to.

Next, the black expansion suppression feedback circuit 4 compares the detection result from the black level detection circuit 3 with the feedback level sent from the black expansion suppression level adjustment circuit 5.

When the black level of the detection result from the black level detection circuit 3 is on the black side of the feedback level sent from the black expansion suppression level adjusting circuit 5, the black expansion suppression feedback circuit 4 operates to perform black expansion correction. The black expansion suppression feedback circuit 4 sends a black expansion suppression signal to the gain control circuit 2 as a voltage value or a current value,
The black expansion correction is suppressed to the level set in the black expansion suppression level adjusting circuit 5.

[0019]

As described above, according to the present embodiment, the black expansion suppression level is externally set to an optimum value to prevent overcorrection of the black expansion correction, and to prevent black crushing from occurring. Optimal black expansion correction control is possible.

[Brief description of drawings]

FIG. 1 is a block diagram of a feedback control device for black expansion correction according to an embodiment of the present invention.

FIG. 2 is a block configuration diagram of a conventional black expansion control device.

[Explanation of symbols]

 1 Black expansion correction circuit 2 Black expansion correction gain control circuit 3 Black level detection circuit 4 Black expansion suppression feedback circuit 5 Black expansion suppression level adjustment circuit 6 Video chroma jungle IC

Claims (1)

[Claims] 1. A black expansion correction circuit for black expansion correction of a luminance signal of a video signal, a black expansion correction gain control circuit for controlling a gain level of the black expansion correction circuit, and a black level of a luminance signal after black expansion correction. A black level detection circuit for detecting a black expansion correction feedback circuit for preventing overexposure of black expansion correction to prevent black crushing, and a black expansion suppression level for arbitrarily setting the black expansion correction suppression level of the black expansion suppression feedback circuit. A feedback control device for black extension correction of a luminance signal, comprising: an adjusting circuit.