JP2007324764A - Video signal processing apparatus and video signal processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a video signal processing apparatus and a video signal processing method for applying high frequency emphasis processing with higher accuracy to a video signal on the basis of the histogram of luminance. <P>SOLUTION: The video signal processing apparatus includes: an input means for receiving a luminance signal; a high frequency emphasis means that extracts a high frequency component from the luminance signal received from the input means, adds the extracted high frequency component to the received luminance signal, and outputs the summated signal; an acquisition means that acquires histogram data for each luminance level from the luminance signal by one frame received by the input means; and a processing means for applying the high frequency emphasis processing to the luminance signal received by the input means on the basis of the histogram data of each luminance level acquired by the acquisition means. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a video signal processing apparatus and a video signal processing method for performing high frequency enhancement processing of a video signal based on a luminance histogram.

  As is well known, in recent years, flat panel type large-screen displays have been developed and put into practical use in television broadcast receivers. By the way, in this type of large screen display, signal correction processing is performed using the luminance component of the video signal in order to make the displayed video clear.

Patent Document 1 discloses a configuration in which contour correction is performed as one of signal correction processes. The control circuit 4 evaluates and determines the luminance distribution, and the contour correction circuit 5 is designed to suppress noise in the luminance level region where the distribution frequency is large, so that noise is suppressed. However, the method according to Patent Document 1 is a method for evaluating and determining a luminance distribution, in which, for example, the contour correction is simply weakened for a range of luminance levels having a number of pixels larger than a predetermined threshold value h1, and contour enhancement is performed. In other words, there has been a problem that an effective control method with sufficiently high accuracy is not disclosed for high-frequency emphasis (sharpness) processing of video signals. For example, when a steep mountain appears in the acquired luminance distribution, it indicates a region where the luminance change is minute and is plain. There was a problem that the possibility of the effect of noise reduction suitable for such a region could not be obtained.
JP 2005-175735 A

  An object of the present invention is to provide a video signal processing apparatus and a video signal processing method for performing high-frequency emphasis processing of a video signal with higher accuracy based on a luminance histogram.

  In order to solve the above-described problems, the video signal processing apparatus according to the present invention extracts an input unit to which a luminance signal is input and a high frequency component extracted from the luminance signal input from the input unit, and inputs the high frequency component. High frequency emphasizing means for adding and outputting to the luminance signal, acquiring means for acquiring histogram data of each luminance level for the luminance signal for one frame input to the input means, and acquired by the acquiring means And processing means for performing high-frequency emphasis processing on the luminance signal input to the input means based on the histogram data of each luminance level.

The video signal processing method includes a first step of inputting a luminance signal and a second step of acquiring histogram data of each luminance level for the luminance signal for one frame input in the first step. The histogram data larger than a predetermined value among the histogram data of each luminance level acquired in the second step is subjected to frequency conversion calculation to a luminance level range corresponding to each luminance level, and the frequency conversion calculation result is Based on the third step of obtaining histogram data corrected by adding to the histogram data of each luminance level acquired in the second step, and the histogram data corrected in the third step, the first A fourth step for creating a high-frequency emphasis processing table for performing high-frequency emphasis processing on the luminance signal input in the step, and a high-frequency emphasis processing table created in the fourth step Based on, characterized by comprising a fifth step of performing high frequency emphasis processing to the first luminance signal inputted in step.

  ADVANTAGE OF THE INVENTION According to this invention, the video signal processing apparatus and the video signal processing method which perform the high region emphasis process of a video signal with higher precision based on the luminance histogram are obtained.

  Examples of the present invention will be described below.

A first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 schematically shows a video signal processing system of a television broadcast receiving apparatus 11 described in the embodiment.
That is, the digital television broadcast signal received by the digital television broadcast receiving antenna 12 is supplied to the channel selection demodulation unit 14 via the input terminal 13. The channel selection / demodulation unit 14 selects a broadcast signal of a desired channel from the input digital television broadcast signal, demodulates the selected signal, and outputs the demodulated signal to the decoder 15.

The decoder 15 decodes the signal input from the channel selection demodulator 14 to generate a digital luminance signal Y and a color signal Cb / Cr, and outputs them to the selector 16.

The analog television broadcast signal received by the analog television broadcast receiving antenna 17 is supplied to the channel selection demodulator 19 via the input terminal 18. The channel selection / demodulation unit 19 selects a broadcast signal of a desired channel from the input analog television broadcast signal, demodulates the selected signal, and generates an analog luminance signal Y and color signal Cb / Cr. Each is generated.

Then, the analog luminance signal Y and the color signal Cb / Cr generated by the channel selection demodulator 19 are supplied to an A / D (analog / digital) conversion unit 20 and the digital luminance signal Y and the color signal Cb / Cr. After being converted to Cr, it is output to the selector 16.

Further, the analog luminance signal Y and the color signal Cb / Cr supplied to the external input terminal 21 for the analog video signal are supplied to the A / D conversion unit 22 and converted into the digital luminance signal Y and the color signal Cb / Cr. After the conversion, it is output to the selector 16. Further, the digital luminance signal Y and the color signal Cb / Cr supplied to the external input terminal 23 for the digital video signal are supplied to the selector 16 as they are.

  Here, the selector 16 selects one of the digital luminance signal Y and the color signal Cb / Cr supplied from the decoder 15, the A / D converters 20 and 22, and the external input terminal 23, respectively, and outputs a video signal. This is supplied to the processing unit 24. As described above, the input means for inputting the luminance signal up to the selector 16 is configured.

As will be described in detail later, the video signal processing unit 24 performs predetermined signal processing on the input digital luminance signal Y and color signal Cb / Cr, thereby providing R (red), G (green), B (blue) signal is generated.

The R, G, and B signals generated by the video signal processing unit 24 are supplied to the video display unit 25 and used for video display. In addition, as this video display part 25, the flat panel display which consists of a liquid crystal display, a plasma display, etc. is employ | adopted, for example.

Here, in the television broadcast receiving apparatus 11, various operations including the above-described various receiving operations are comprehensively controlled by the control unit 26. The control unit 26 is a microprocessor with a built-in CPU (central processing unit) and the like, receives operation information from an operation unit 27 including a remote controller (not shown), and sets each unit so that the operation content is reflected. I have control.

  In this case, the control unit 26 mainly includes a ROM (read only memory) 28 storing a control program executed by the CPU, a RAM (random access memory) 29 for providing a work area to the CPU, A nonvolatile memory 30 in which setting information, control information, and the like are stored is used.

FIG. 2 shows an example of the video signal processing unit 24. That is, the digital luminance signal Y and color signal Cb / Cr selected by the selector 16 are supplied to an IP (interlace progressive) conversion / scaling processing unit 32 via the input terminals 31a and 31b.

The IP conversion / scaling processing unit 32 is progressive in order to display the input luminance signal Y and color signal Cb / Cr on the video display unit 25 (a flat panel display such as a liquid crystal display or a plasma display). Conversion processing and scaling processing are performed, and the result is output to the enhancer processing unit 33.

The enhancer processing unit 33 performs an enhancer process on the input luminance signal Y and color signal Cb / Cr so that the vertical and horizontal rising edges are sharp or the sharpness is changed. 34 is output. The enhancer process relates to a high-frequency emphasis process of a video signal that is a target of the signal correction process. The histogram acquisition unit 33 a is connected to input the luminance signal from the IP conversion / scaling processing unit 32 and output the result of acquiring the luminance signal histogram to the enhancer processing unit 33.

  The signal correction unit 34 performs non-linear correction processing for tone correction on the input luminance signal Y, and also performs amplitude control processing on the color signal Cb / Cr in accordance with the non-linear correction processing. The data is output to the space conversion unit 35.

The color space conversion unit 35 converts the input luminance signal Y and color signal Cb / Cr into R, G, and B signals and outputs them to the RGB gamma correction unit 36. The RGB gamma correction unit 36 performs white balance adjustment on the input R, G, and B signals, performs gamma correction processing on the video display unit 25, and outputs the result to the dither processing unit 37.

Then, the dither processing unit 37 applies a high-gradation bit representation with an expanded number of bits to the input R, G, and B signals so as to increase the expressive power. After performing compression processing to convert the number of bits into a key, the data is output to the video display unit 25 via the output terminals 38, 39, and 40.

FIG. 3 shows an example of a configuration using the luminance signal of the enhancer processing unit 33. It is connected to a histogram acquisition unit 33a, which is an acquisition means for acquiring histogram data divided by the lower left broken line. That is, the luminance signal Y output from the IP conversion / scaling processing unit 32 connected to the input means to which the luminance signal is input is given to the frame memory 42 as the signal input 41, so that first one frame delay processing is performed. It has become. This is because the acquisition of a histogram for one frame of an image has to be performed, and the purpose is to delay the acquisition period. The delayed signal is configured such that an arbitrary high-frequency component is extracted by the secondary differential calculation circuit 43 and subjected to a coring process 44 in order to remove a minute signal component such as noise. Then, the amount of enhancement is determined by the value given by the LUT storage SRAM 45 by the multiplier 46, added to the frame delay signal as the source signal from the adder 47, a high frequency enhancement operation is performed, and output as a signal output 48. It has become.

As a process of controlling the high frequency enhancement amount, the input signal 41 is first input to the histogram acquisition unit 33a, and the number of pixels at each level is measured. Histogram data of each luminance level is acquired for the input luminance signal for one frame. At this time, the level decomposition number is sufficiently fine with respect to the dynamic range of the input signal 1. (For example, 256 divisions with 8-bit resolution). When one frame is acquired, the histogram information 50 is input to a program that operates on the processor 51, calculates the LUT 52 that is the high frequency emphasis amount of each level, and sets it in the LUT storage SRAM 45. That is, the LUT storage SRAM 45 constitutes processing means for performing high frequency emphasis processing on the luminance signal, in particular, creating means for creating a high frequency emphasis processing table together with the processor 51, and the adder 47 performs high frequency emphasis processing for performing high frequency emphasis processing. Means. Of the processing means for performing high-frequency emphasis processing on the luminance signal, the processor 51 serves as control means, and the LUT storage SRAM 45 serves as conversion means.

The high frequency enhancement amount is performed by checking the signal level delayed by one frame, referring to the enhancement amount corresponding to the level from the LUT storage SRAM 45, and outputting it to the multiplier 46.

  FIG. 4 is a flowchart summarizing an example of LUT calculation performed on the luminance signal Y by the high frequency emphasis correction processing unit 42. That is, when the process is started (step S1), the histogram acquisition circuit 33a acquires histogram data DIN (1) to DIN (n) for the respective luminance levels 1 to n in step S2.

The histogram data is acquired by dividing the luminance level dynamic range into n and counting the number of pixels corresponding to each of the luminance levels 1 to n for one frame of the video signal. In this case, the resolution of the luminance levels 1 to n is set sufficiently fine. For example, when the input video signal is 8 bits, the resolution of the luminance level when acquiring the histogram data is also 8 bits.

FIG. 5 shows an example of luminance histogram data for one frame acquired as described above. In this case, the resolution of the luminance level is 8 bits (0 to 255). That is, the number of pixels corresponding to each of 256 luminance levels from 0 to 255 is acquired. Therefore, when all the numbers of pixels at each luminance level are added, the total is the same as the number of pixels for one frame of the input video signal. Hereinafter, it will be generalized as 1 to n again instead of 0 to 255.

Thereafter, the processor 51 performs frequency distribution processing on the acquired histogram data DIN (1) to DIN (n) based on the control data supplied from the control unit 26. First, in step S3 in FIG. 4, the processor 51 detects a plain area with a very small brightness level difference for the histogram data DIN (1) to DIN (n) of each brightness level 1 to n. The absolute value of the difference between the level i before and after (i−1, i + 1) is calculated, and the larger one (DIN (0) and DIN (n + 1) at both ends are calculated as 0) is calculated as Dhds1 ( Get as i). Next, in step S4, the processor 51 subtracts the deviation upper limit coefficient HDE from Dhds1 (1) to Dhds1 (n) of each luminance level 1 to n to obtain Dhds2 (i). If the value is too large, the correction amount becomes too large, so that it operates as a limiter. Next, in step S5, the processor 51 subtracts the deviation lower limit coefficient HDS from Dhds2 (i) of each luminance level 1 to n to obtain Dhds3 (i). In this case, when the area is smaller than the area to be corrected, the value is set to 0 so that the processing is not performed.

Thereafter, in step S6, the processor 51 performs frequency distribution processing to obtain Dhds4. An example of the calculation is described in the following numbers 1 to 4, and thereby, a process of further enlarging the region to be corrected obtained by the histogram is performed. This is because, when the region is set accurately, the high frequency emphasis level fluctuates even if there is a slight fluctuation in the contour portion of the image, and there is a visual problem. Any of the numbers 1 to 4 may be used as appropriate, but the greater the number, the greater the effect of suppressing fluctuations. Those having a smaller or larger function than this range may be used.

1.
Dhds3 (i), Dhds3 (i-1), 0.875 * Dhds3 (i-2), 0.75 * Dhds3 (i-3), 0.625 * Dhds3 (i-4), 0.5 * Dhds3 (i-5), 0.375 * Dhds3 (i-6), 0.25 * Dhds3 (i-7), 0.125 * Dhds3 (i-8), Dhds3 (i + 1), 0.875 * Dhds3 (i + 2), 0.75 * Dhds3 (i + 3), 0.625 * Dhds3 (i + 4), 0.5 * Dhds3 (i + 5), 0.375 * Dhds3 (i + 6), 0.25 * Dhds3 (i + 7), 0.125 * Dhds3 (i + 8) obtained as i)

2.
Dhds3 (i), Dhds3 (i-1), Dhds3 (i-2), 0.875 * Dhds3 (i-3), 0.75 * Dhds3 (i-4), 0.625 * Dhds3 (i-5), 0.5 * Dhds3 ( i-6), 0.375 * Dhds3 (i-7), 0.25 * Dhds3 (i-8), 0.125 * Dhds3 (i-9), Dhds3 (i + 1), Dhds3 (i + 2), 0.875 * Dhds3 ( i + 3), 0.75 * Dhds3 (i + 4), 0.625 * Dhds3 (i + 5), 0.5 * Dhds3 (i + 6), 0.375 * Dhds3 (i + 7), 0.25 * Dhds3 (i + 8), 0.125 * Obtain the maximum value as Dhds4 (i) from Dhds3 (i + 9)

3.
Dhds3 (i), Dhds3 (i-1), Dhds3 (i-2), Dhds3 (i-3), 0.875 * Dhds3 (i-4), 0.75 * Dhds3 (i-5), 0.625 * Dhds3 (i- 6), 0.5 * Dhds3 (i-7), 0.375 * Dhds3 (i-8), 0.25 * Dhds3 (i-9), 0.125 * Dhds3 (i-10), Dhds3 (i + 1), Dhds3 (i + 2), Dhds3 (i + 3), 0.875 * Dhds3 (i + 4), 0.75 * Dhds3 (i + 5), 0.625 * Dhds3 (i + 6), 0.5 * Dhds3 (i + 7), 0.375 * Dhds3 ( i + 8), 0.25 * Dhds3 (i + 9), 0.125 * Dhds3 (i + 10), get the maximum value as Dhds4 (i)

4).
Dhds3 (i), Dhds3 (i-1), Dhds3 (i-2), Dhds3 (i-3), Dhds3 (i-4), 0.875 * Dhds3 (i-5), 0.75 * Dhds3 (i-6) , 0.625 * Dhds3 (i-7), 0.5 * Dhds3 (i-8), 0.375 * Dhds3 (i-9), 0.25 * Dhds3 (i-10), 0.125 * Dhds3 (i-11), Dhds3 (i + 1), Dhds3 (i + 2), Dhds3 (i + 3), Dhds3 (i + 4), 0.875 * Dhds3 (i + 5), 0.75 * Dhds3 (i + 6), 0.625 * Dhds3 (i + 7) , 0.5 * Dhds3 (i + 8), 0.375 * Dhds3 (i + 9), 0.25 * Dhds3 (i + 10), 0.125 * Dhds3 (i + 11) Get the maximum value as Dhds4 (i)

In step S7, the processor 51 multiplies the value Dhds4 (i) by the value HDG (i), that is,
Dhds5 (i) = Dhds4 (i) × HDG (i)
The multiplication value Dhds5 (i) is calculated by performing the following calculation. The calculation process in step S8 is performed for each of the luminance levels 1 to n. Sets the gain for determining the final correction amount. This provides a data amount for levels 1 to n. HDG (i) is a number between 0 and 1, with 1 being the best effect and 0 being ineffective. It is only necessary that the user can select the device menu or the like in several stages such as strong, medium, weak, and off during this period.

Next, in step S8, the processor 51 performs high frequency emphasis gain reference values Dds (1) to Dds (n) for the histogram data DIN (1) to DIN (n) of the respective luminance levels 1 to n. To get. This is a gain setting used as a reference when correction by the histogram value is not performed.

Next, in step S9, the processor 51 applies the high frequency emphasis gain lower limit values Su (1) to Su (n) to the histogram data DIN (1) to DIN (n) of the luminance levels 1 to n, respectively. To get.

Then, the processor 51 subtracts the value Dhds5 (i) from the value Dds (i) in step S10, that is,
Dhds6 (i) = Dds (i) −Dhds5 (i)
Is calculated to calculate a subtraction value Dhds6 (i). Thereby, the correction obtained from the histogram value from the set value of the high frequency emphasis gain as the reference value is performed.

Thereafter, in step S11, the processor 51 compares Dhds6 (i) [i = 1 to n] with the value Su (i) to obtain the larger one as Dhds7 (i). This is done in order to prevent the user from setting a limit value at which correction is performed and correcting it excessively. That means

Dhds7 (i) = MAX (Dhds6 (i), Su (i))
To calculate the value Dhds7 (i). This is done in order to prevent the user from setting a limit value at which correction is performed and overcorrecting.
The arithmetic processing in steps S10 and S11 is performed for each of the luminance levels 1 to n. When the subtraction result is negative, Dhds7 (i) is set to 0.

In step S12, Dhds7 is output as a result. This is the LUT 52 output from the processor 51, and the flow for correcting the high-frequency emphasis effect amount is completed (step S13).

Here, FIG. 6 shows the above-described high-frequency emphasis processing on the characteristic diagram of the histogram data. First, as shown in FIG. 6 (a), the absolute value of the inclination as shown by the solid line in (b) with respect to the histogram data DIN (1) to DIN (n) having a wide distribution of each luminance level 1 to n. The difference Dhds1 (i) is acquired. Here, since Dhds1 (i) is always smaller than HDE, Dhds2 (i) is the same line as Dhds1 (i). Since Dhds2 (i) is always smaller than HDS, the value is always 0 for Dhds3 (i). For this reason, the value of the next Dhds4 (i) is always 0, and no emphasis is eased on the reference values Dds (1) to Dds (n) of the high frequency emphasis gain.

On the other hand, in FIG. 6 (c), unlike (a), the narrower histogram data DIN (1) to DIN (n) of the distribution of each luminance level 1 to n is inclined as shown by the solid line in (d). The absolute value difference Dhds1 (i) is obtained. Here, Dhds1 (i) is cut off by HDE and Dhds2 (i) is cut off by HDS, and Dhds3 (i) has the distribution shown by the broken line in (e). When Dhds4 (i) is calculated from this Dhds3 (i), a solid line of (e) is obtained. This is a correction that widens the range of steep edges that prevents sharpness from changing suddenly when viewed by the viewer. The emphasis is reduced for the reference values Dds (1) to Dds (n) of the high frequency emphasis gain by the amount of Dhds4 (i).

According to the embodiment described above, by acquiring the luminance level and the area occupied on the screen as information, for example, a plain image having a large area at a specific luminance level (for example, a blue sky photographed image) In this case, it is possible to detect such a part and to specifically limit the high frequency emphasis. By calculating both ends (lower and upper ends at the input luminance level) of the peak portion of this luminance distribution, and limiting the high frequency emphasis gain for that range, it is placed on a plain image (for example, the blue sky on the entire surface). It becomes possible not to perform emphasis on the noise component.

  As a result, it is possible to make the noise inconspicuous by performing processing such as not emphasizing noise or the like that has been placed in the blue sky portion (further, coring processing by inversion addition).

  In a system having means for controlling the gain of high-frequency emphasis (sharpness) according to the brightness level of the processed image pixel and means for acquiring a histogram based on the brightness of the processed image, the optimum content at each brightness level depends on the content of the acquired histogram. A system for controlling the high frequency emphasis gain is provided.

  Based on the tendency of the acquired histogram, when the proportion of the luminance of the same level on the screen is large (large area), the basic operation is to work to lower the high-frequency emphasis gain below the reference value for that level. .

Note that the present invention is not limited to the above-described embodiments as they are, and can be embodied by variously modifying the constituent elements without departing from the scope of the invention in the implementation stage. Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above-described embodiments. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements according to different embodiments may be appropriately combined.

The block block diagram shown in order to demonstrate the video signal processing system of the television broadcast receiver which shows embodiment of this invention. The block block diagram shown in order to demonstrate the detail of the video signal processing part of the television broadcast receiver in the embodiment. The block block diagram shown in order to demonstrate the detail of the enhancer process part of the video signal process part in the embodiment. The flowchart shown in order to demonstrate the processing operation of the high region emphasis correction process part in the embodiment. The figure shown in order to demonstrate the histogram data for 1 frame which the high frequency emphasis correction process part in the embodiment acquires. The figure shown in order to demonstrate an example of the high region emphasis processing operation of the high region emphasis correction process part in the embodiment.

Explanation of symbols

11 ... Television broadcast receiver, 12 ... Antenna, 13 ... Input terminal, 14 ... Channel selection demodulator, 15 ... Decoder, 16 ... Selector, 17 ... Antenna, 18 ... Input terminal, 19 ... Channel selection demodulator, 20 ... A / D conversion unit, 21 ... external input terminal, 22 ... A / D conversion unit, 23 ... external input terminal, 24 ... video signal processing unit, 25 ... video display unit, 26 ... control unit, 27 ... operation unit, 28 ... ROM, 29 ... RAM, 30 ... nonvolatile memory, 31a, 31b ... input terminal, 32 ... IP conversion / scaling processing unit, 33 ... enhancer processing unit, 33a ... histogram acquisition unit, 34 ... signal correction unit, 35 ... color Spatial conversion unit, 36 ... RGB gamma correction unit, 37 ... dither processing unit, 38-40 ... output terminal, 41 ... signal input, 42 ... frame memory, 43 ... secondary differential calculation circuit, output terminal, 44 ... coring processing 45 ... LUT storage SRAM 46 ... multiplier 47 ... adder 48 ... signal output 49 ... histogram information 51 ... pro Tsu service, 52 ... LUT.

Claims (12)

An input means for inputting a luminance signal;
A high frequency emphasizing unit that extracts a high frequency component from the luminance signal input from the input unit, adds the high frequency component to the input luminance signal, and outputs it;
Acquisition means for acquiring histogram data of each luminance level for the luminance signal for one frame input to the input means;
A video signal processing apparatus comprising: processing means for performing high-frequency emphasis processing on the luminance signal input to the input means based on histogram data of each luminance level acquired by the acquisition means.   The processing means adjusts the effect of the high frequency emphasis means according to the level of the luminance signal input from the input means, and the effect amount of the high frequency emphasis means according to the level of the luminance signal input from the input means 2. The video signal processing device according to claim 1, further comprising conversion means for determining the video signal.   The processing means performs frequency conversion processing on the histogram data based on a predetermined value, corrects a preset high frequency enhancement amount based on the histogram data corrected by the frequency conversion processing, and stores the high frequency enhancement in the LUT. 2. The video signal processing apparatus according to claim 1, further comprising a table creation unit. The high frequency emphasis table creating means includes
Subtraction means for taking a difference of histogram data from the histogram data of each luminance level acquired by the acquisition means, and subtracting a preset threshold value corresponding to each luminance level from the difference data;
Multiplication means for multiplying each subtraction value obtained from the subtraction means by a weighting coefficient set in advance corresponding to each luminance level;
4. The video according to claim 3, further comprising correction means for correcting a high-frequency emphasis effect amount set in advance corresponding to each luminance level based on each multiplication result obtained from the multiplication means. Signal processing device.   5. The video signal processing apparatus according to claim 4, wherein the subtracting unit outputs 0 when the subtraction result becomes negative.   2. A processing unit for obtaining a delayed signal and extracting a high frequency component from the luminance signal for one frame input to the input unit and deleting a minute signal component from the extracted high frequency component is further added. The video signal processing apparatus described.   5. The video signal processing apparatus according to claim 4, further comprising frequency dispersion processing means for performing frequency dispersion processing prior to the multiplication to each subtraction value obtained from the subtraction means. A first step of inputting a luminance signal;
For the luminance signal for one frame input in the first step, a second step of acquiring histogram data of each luminance level;
Histogram data larger than a predetermined value among the histogram data of each luminance level acquired in the second step is subjected to frequency conversion calculation in a luminance level range corresponding to each luminance level, and the frequency conversion calculation result is converted to the frequency conversion calculation result. A third step of obtaining histogram data corrected by adding to the histogram data of each luminance level acquired in step 2,
Based on the histogram data corrected in the third step, a fourth step of creating a high frequency enhancement processing table for performing high frequency enhancement processing on the luminance signal input in the first step;
And a fifth step of applying a high frequency enhancement process to the luminance signal input in the first step based on the high frequency enhancement processing table created in the fourth step. Video signal processing method. The fourth step includes
A sixth step of subtracting a preset threshold value corresponding to each luminance level from the histogram data of each luminance level acquired in the second step;
9. The video signal according to claim 8, further comprising a seventh step of multiplying each subtraction value obtained in the sixth step by a weighting coefficient set in advance corresponding to each luminance level. Processing method.   The video signal processing method according to claim 9, wherein the sixth step outputs 0 when the subtraction result is negative.   An eighth step of obtaining a delay signal from the luminance signal of one frame input in the first step, extracting a high frequency component, and deleting a minute signal component from the extracted high frequency component; 9. The video signal processing method according to claim 8, which is added.   10. The video signal processing method according to claim 9, wherein a frequency distribution process is performed on each subtraction value obtained in the sixth step prior to the seventh step.

Images