JP3318755B2 - Video signal processing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal processing apparatus, and based on a spectral distribution of a luminance signal of an input video signal, a so-called frequency characteristic of a video signal amplification circuit, hue, color, and the like. contrast,
The present invention relates to a video signal processing device for adjusting image quality such as sharpness and brightness.

B. Summary of the Invention In a video signal processing apparatus according to the present invention, a spectrum distribution detecting means for detecting a spectral distribution of a luminance signal of an input video signal, and a spectrum distribution detecting means for detecting a spectral distribution of the luminance signal of the input video signal from the spectral distribution detecting means. Signal processing means for performing predetermined image quality adjustment processing on an input video signal so that the image quality such as frequency characteristics, hue, color, contrast, sharpness, and brightness of a so-called video signal amplifier circuit can be automatically adjusted. It was done.

C. Prior Art In recent years, for example, with the enlargement of the screen of a television receiver, the resolution of the television receiver has been increased.
In order to increase the resolution of a screen, for example, the frequency characteristics of a video signal amplifier circuit that amplifies a video signal is extended to a high frequency range.

In addition, the television receiver includes various adjustment means for adjusting image quality, for example, hue (hue), color saturation (color), contrast, sharpness (sharpness), brightness (brightness), etc. according to a user's preference. Is provided.

D. Problems to be Solved by the Invention By extending the frequency characteristics of the video signal amplifier circuit to a higher frequency range, the resolution is improved.For example, the spectrum of the luminance signal of the input video signal at a certain point is distributed to the higher frequency range. When there is no change, that is, when there is a monotonous screen with little change, there is a problem that the image quality is rather deteriorated due to deterioration of a so-called S / N (Signal to Noise ratio) caused by extending the frequency characteristic to a high frequency range. In particular, for example, a device using a video signal having a band of 30 MHz, such as a so-called high-definition television, has a noisy image.

Further, the image displayed on the television receiver is constantly changing with the lapse of time except for a still image, and at a certain point in time, the above image quality, for example, brightness, color, sharpness, etc. Even if the adjustment is made such that the image quality becomes as follows, the best image quality is not always obtained at the next point in time.

For example, when the brightness is adjusted on a bright screen, the brightness is usually adjusted to a level at which the screen becomes slightly darker. Then, once the brightness is set to a desired level by the user when the screen is bright, when the screen changes to dark at the next point, the screen becomes so-called "black-out" or "black-up". And the best image quality could not always be obtained.

For example, on a bright screen, sharpness is increased to increase the sharpness of an image. On a dark screen, the so-called preshoot and overshoot of a video signal are conspicuous as noise, so it is better to reduce the sharpness. ing. Further, for example, it is considered that the color level should be lowered because the noise due to the color signal is conspicuous on a dark screen, and the color is insufficient on a bright screen.

The present invention has been made in view of such circumstances, and has a spectral distribution of a luminance signal of an input video signal, a frequency characteristic of a video signal amplifier circuit according to a change in the spectral distribution, and image quality such as brightness, color, and sharpness. And a video signal processing device capable of automatically controlling the video signal.

E. Means for Solving the Problems In order to solve the above problems, a video signal processing device according to the present invention is a video signal processing device that separates a brightness signal from an input video signal, Band dividing means for dividing the divided luminance signal into a plurality of frequency bands, and detecting the level of each frequency component of the luminance signal divided into the plurality of frequency bands by the band dividing means to thereby obtain a spectrum of the luminance signal of the input video signal. A spectrum distribution detecting means for detecting a distribution, a storage means for storing adjustment level data for image quality adjustment measured in advance, and the spectrum distribution detecting means based on a spectrum distribution of a luminance signal of an input video signal detected by the spectrum distribution detecting means. Reading means for reading the adjustment level data stored in the storage means; and the adjusting means read by the reading means. Characterized by a signal processing means for performing a comprehensive image adjustment processing to an input video signal based on the level data.

F. Action In the video signal processing apparatus according to the present invention, the image quality such as brightness, color, and sharpness is adjusted in accordance with the spectral distribution of the luminance signal of the input video signal and a change in the spectral distribution, and the video signal whose image quality has been adjusted is adjusted. Output.

G. Embodiment Hereinafter, an embodiment of a video signal processing device according to the present invention will be described with reference to the drawings.

As shown in FIG. 1, a video signal processing apparatus generates a so-called RGB signal from a memory 11 for delaying an input video signal by a predetermined time and a video signal from the memory 11, and converts the RGB signal into a cathode ray tube (hereinafter, referred to as a cathode ray tube). Signal processing circuit 1 to supply to 13
2, a luminance signal separation circuit 14 for separating a luminance signal (Y signal) from an input video signal, and a low-pass filter and a band-pass filter (hereinafter, referred to as “pass”) that pass predetermined frequency components of the luminance signal from the luminance signal separation circuit 14. filter that) F ₁ ~
And F _n, (hereinafter referred to as A / D converter) the filter F ₁ the level of each frequency component from the to F _n each analog / digital converter for converting the digital signal and AD ₁ to AD _n, the A / D The digital signal of each frequency component level from the converter conversions AD _{1 to} AD _n is analyzed, and the signal processing circuit 12 is analyzed based on the analysis result.
And an analysis control circuit 15 for controlling an image quality adjustment circuit to be described later.
The image signal is supplied to the luminance signal separation circuit 14, and is amplified by the signal processing circuit 12 from the memory 11 to perform image quality adjustment signal processing, which will be described later, and is converted into an RGB signal. Then, an image corresponding to the RGB signal is displayed on the CRT 13.

Specifically, as shown in FIG. 2, the filters F _{1 to} F _n have a pass bandwidth (BW) of 0.5 MHz, the filter F ₁ passes DC to 0.5 MHz components, and the filter F _{1 2} is 0.5 to 1.0
It passes through the MH components, and so on, the filter F _n is 29.5～
It is designed to pass 30.0 MH components.

The signal processing circuit 12 includes a video signal amplifying circuit, the image quality adjusting circuit, a so-called matrix circuit, and the like. The video signal amplifier circuit amplifies the video signal. The image quality adjustment circuit has a frequency characteristic adjustment function for adjusting the frequency characteristics of the video signal amplification circuit, a hue (hue) adjustment function, a color saturation (color) adjustment function, a contrast adjustment function, and a sharpness (sharpness) adjustment function. have various image quality adjustment functions such as brightness (brightness) adjustment function, according to the spectral distribution of the luminance signal of the filter F ₁ to F _n levels of each frequency component of the extracted luminance signal, that is, the input video signal The above-mentioned various image quality adjustment functions are
Controlled by 15. Also, the above matrix circuit
An RGB signal is generated from a video signal whose image quality has been adjusted.

In addition, the delay time of the memory 11 is determined by the filters F ₁ to F ₁ .
F _n matches the processing time in the A / D converters AD _{1 to} AD _n and the analysis control circuit 15.

Next, a specific operation of the video signal processing device having the above configuration will be described.

For example, _if the number of bits of the A / D converters AD _{1 to} AD _n is 8 bits, the level of each frequency component of the luminance signal of the input video signal (hereinafter referred to as frequency component data) is “0” in hexadecimal notation.
Then, the analysis control circuit 15 converts these 8-bit frequency component data into, for example, DC to 1
0.0MHz band data, 10.0 ~ 20.0MHz band data, 20.
Divide into data of 0-30.0MHz band. Next, for example, 2-bit code data f _L , f _M , and f _H are formed in each band according to each frequency component data in the band. Then, the analysis control circuit 15 outputs these code data f _L , f _M ,
controlling the image quality adjustment circuit of the signal processing circuit 12 on the basis of f _H.

Specifically, as shown in Table 1 below, each time t ₁ ,
At t ₂ , t ₃ ,..., the low-frequency code data f _L , the middle-frequency code data f _M , and the high-frequency code data f _H are analyzed and controlled.
Required by 15.

Then, Ni will Okeyo, for example, the time t _9, code data f _L
= 2, f _M = 0, f _H = 0, when the luminance signal of the input video signal contains only a low-frequency component and the level of the luminance signal is low, the bandwidth of the video signal amplifier circuit is narrowed. Suppress high frequency noise to improve S / N.

Moreover, as at time t ₁₀ For example, code data f
_L = 1, as indicated by _{f M = 2, f H =} 2, with contains many middle band component and the high frequency component to the luminance signal of the input video signal, increases the level of the luminance signal from the time t ₉ changes In such a case, peaking is applied to the video signal to enhance sharpness.

That is, according to the spectral distribution of the luminance signal of the video signal and the change in the spectral distribution, the frequency characteristics of the video signal amplifier circuit, hue, color, contrast, sharpness,
By adjusting the brightness and the like, it is possible to obtain the spectral distribution of the luminance signal of the input video signal and the best image quality corresponding to the change in the spectral distribution.

The levels of hue, color, contrast, sharpness, brightness, etc. suitable for the above-mentioned spectral distribution and changes in the spectral distribution are obtained, for example, by experiments in advance, and stored in a read-only memory in the analysis control circuit 15. In advance, the data is read in accordance with the spectral distribution or a change in the spectral distribution, that is, the code data. That is, the analysis control circuit 15 reads out the adjustment level of various image quality in the read-only memory with the code data formed based on each frequency component data as described above, thereby real-time (real-time) video signal. And an adjustment level of the luminance signal can be obtained.
In other words, the spectral distribution of the luminance signal of the input video signal and the image quality adjustment corresponding to the change in the spectral distribution can be performed in real time.

As described above, in the present invention, the analysis control circuit 15 analyzes the spectral distribution of the luminance signal of the input video signal and changes in the spectral distribution to form code data of each band,
With this code data, various image quality adjustment levels are obtained,
By controlling the image quality adjustment circuit of the signal processing circuit 12 with these adjustment levels, the spectral distribution of the luminance signal of the input video signal, the frequency characteristics of the video signal amplifier circuit, brightness, color, sharpness, etc. Image quality can be automatically controlled.

The present invention is not limited to the above embodiment. For example, the delay time of the memory 11 is obtained by adding one horizontal scanning time to the processing time of the analysis control circuit 15 and the like. The image quality may be adjusted by analyzing the change in the spectral distribution between the horizontal scanning lines (lines). For example, the delay time of the memory 11 is obtained by adding one field (vertical) scanning time or one frame scanning time to the processing time of the analysis control circuit 15 and the like.
The analysis control circuit 15 may analyze the change in the spectrum distribution between fields or between frames, that is, in the time axis direction, and adjust the image quality.

H. Effects of the Invention As is clear from the above description, in the present invention, the luminance signal separated from the input video signal by the luminance signal separating means is divided into a plurality of frequency bands by the band dividing means, and each of the luminance signals is By detecting the level of the frequency component, the spectrum distribution of the luminance signal of the input video signal is detected by the spectrum distribution detection means, and the image adjustment for image adjustment obtained by measuring the reference video signal stored in the storage means is obtained. The adjustment level data is read out by the reading means based on the spectral distribution of the luminance signal of the input video signal, and comprehensive image quality adjustment processing is performed on the input video signal based on the read out adjustment level data, so that the brightness of the input video signal is improved. Adjustment levels selected from data measured by experiments, etc., according to the spectral distribution of the signal and changes in the spectral distribution. Utilizing data, frequency characteristics of the video signal amplifier circuit, brightness, can be automatically controlled color, the image quality of the sharpness or the like.

[Brief description of the drawings]

Figure 1 is a block circuit of an embodiment of a video signal processing apparatus according to the present invention, FIG. 2 filters F ₁ ~ shown in Figure 1
Is a diagram showing the frequency characteristic of F _n. F ₁ … Low-pass filter F _{2 to} F _n … Band-pass filter AD _{1 to} AD _n … A / D converter 12… Signal processing circuit 15… Analysis control circuit

Claims (1)

(57) [Claims] A luminance signal separating unit for separating a luminance signal from an input video signal; a band dividing unit for dividing the luminance signal separated by the luminance signal separating unit into a plurality of frequency bands; Spectrum distribution detecting means for detecting the spectrum distribution of the luminance signal of the input video signal by detecting the level of each frequency component of the luminance signal divided into the frequency band of Storage means for storing; read means for reading adjustment level data stored in the storage means based on a spectrum distribution of a luminance signal of an input video signal detected by the spectrum distribution detection means; A signal for subjecting the input video signal to comprehensive image adjustment processing based on the adjustment level data A video signal processing apparatus characterized by having a physical means.