JP2003333615A - Video signal processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a video signal processor which improves a color resolution by extending a band of color difference signals. <P>SOLUTION: The video signal processor is provided with a color difference signal similar line detection circuit 5 for detecting two similar adjacent lines of an input color difference signal C, luminance signal averaging circuits 6 to 8 for acquiring an average value of input luminance signals Y corresponding to the detected similar lines, a luminance signal low band component extraction circuit 14 for extracting a low band component of the average value of input luminance signals Y, a luminance signal high band component extraction circuit 13 for extracting a high band component of the average value of the input luminance signals Y, a color difference signal low band component extraction circuit for extracting a low band component of the input color difference signal C, a first arithmetic circuit 19 for calculating a ratio of the low band component of the input color difference signal C to the low band component of the input luminance signals Y, a second arithmetic circuit 21 for calculating a high band correction component of the input color difference signal C on the basis of the high band component of the input luminance signals Y and the ratio, and an addition circuit 24 for adding the low band component of the input color difference signal C and the high band correction component to acquire a high band corrected color difference signal. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal processing device in a television receiver such as a plasma display device, and more particularly to a video signal processing capable of improving color resolution by expanding the band of color difference signals. Regarding the device.

[0002]

2. Description of the Related Art Conventionally, DVD (Digital Ver.
In a digital video device such as a serrate disc player, image information is processed as a digital signal obtained by sampling one luminance signal Y and two color difference signals Cr and Cb. MPEG (Moving Picture)
In the Expert Group 2 system, in order to reduce the data rate of recording and reproducing digital image information,
The image information is compressed. To compress an image in this way, a method of deleting color information by utilizing the fact that human visual characteristics are not sensitive to color is common, and one luminance signal Y and two color difference signals Cr and Cb are used. Expressed as 4: 2: 0
Format is used. In the progressive scanning digital signal of the 4: 2: 0 format, the color information, that is, the color difference signals Cr and Cb are set to 1/2 the number of samples of the luminance signal Y in both the horizontal and vertical directions.

[0003]

[Problems to be Solved by the Invention]
When an image of a progressive scanning digital signal of the above format is displayed as an image, for example, the same color difference signal is output every two lines. Therefore, in such a color difference signal, the high frequency component of the color difference signal is impaired, which causes a problem that color unevenness occurs.

Therefore, the present invention has been made in view of the above problems, and an object thereof is to provide a video signal processing device capable of improving color resolution by expanding the band of color difference signals. Especially.

[0005]

In order to solve the above-mentioned problems, the invention according to claim 1 is a color difference signal similar line detection circuit for detecting two adjacent lines having similar input color difference signals, A luminance signal averaging circuit that obtains an average value of the input luminance signal corresponding to the detected similar line, a luminance signal low-frequency component extraction circuit that extracts a low-frequency component of the average value of the input luminance signal, and the input luminance A luminance signal high frequency component extraction circuit for extracting a high frequency component of a signal average value, a color difference signal low frequency component extraction circuit for extracting a low frequency component of the input color difference signal, and an input for the low frequency component of the input luminance signal A first arithmetic circuit for calculating a ratio of a low frequency component of the color difference signal; a second arithmetic circuit for calculating a high frequency component of the input color difference signal based on the high frequency component of the input luminance signal and the ratio; Low input color difference signal Characterized by comprising an adding circuit for obtaining a by adding said high frequency correction component as the high-frequency-corrected color difference signal.

With this configuration, in the invention according to claim 1, two adjacent lines having similar input color difference signals are detected by the color difference signal similar line detection circuit, and the input luminance signal corresponding to the detected similar line is detected. And calculates the ratio of the low frequency component of the input color difference signal to the low frequency component of the input luminance signal, and corrects the high frequency component of the input color difference signal based on this ratio and the high frequency component of the input luminance signal. Since the components are calculated and the low-frequency component of the color difference signal and the high-frequency correction component of the luminance signal are added to obtain the high-frequency-corrected color difference signal, the color resolution in the vertical direction can be improved. .

In order to solve the above-mentioned problems, the invention according to claim 2 is the video signal processing device according to claim 1, wherein the input color difference signal is a progressive scan video signal in a 4: 2: 0 format. It is a color difference signal.

With this configuration, in the invention according to claim 2, since the input color difference signal is a color difference signal of a progressive scanning video signal in the 4: 2: 0 format, the color resolution in the vertical direction is the same as in the first aspect. Can be improved.

In order to solve the above-mentioned problems, the invention according to claim 3 is the video signal processing device according to claim 1 or 2, wherein the input color difference signal is a progressive scan image in a 4: 2: 0 format. When the color difference signal of the signal is a color difference signal of the interlaced scanning video signal of the 4: 2: 0 format, while the color difference signal corrected by high frequency output from the adding circuit is transmitted, An output switching circuit for transmitting the low frequency component of the color difference signal is provided.

With this configuration, according to the third aspect of the invention, the output can be switched depending on whether the input color difference signal is the color difference signal of the progressive scanning video signal or the color difference signal of the interlaced scanning video signal. Because I chose
It is possible to appropriately select whether to transmit the high-frequency-corrected color difference signal or the low-frequency component of the color difference signal.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a video signal processing apparatus according to the present invention, and FIG. 2 is 4: 2: 0 of FIG.
It is explanatory drawing which shows the color difference signal of the progressive scan video signal of a format.

In this embodiment described below, the high frequency components of the color difference signals Cr and Cb which are not transmitted and the luminance signal Y are not transmitted.
Of the color difference signals Cr and Cb and the low frequency component of the luminance signal Y (excluding the direct current component) are substantially equal to High-frequency component of signal Y, low-frequency component of color difference signals Cr and Cb (excluding DC component), and low-frequency component of luminance signal Y (excluding DC component)
The high frequency components of the color difference signals Cr and Cb are estimated by the ratio of In the following description, the color difference signals Cr,
Cb is collectively referred to as a color difference signal C, and the input luminance signal Y and color difference signal C are a luminance signal and a color difference signal of a progressive scanning video signal or an interlaced scanning video signal in a 4: 2: 0 format.

The video signal processing apparatus of this embodiment is shown in FIG.
As shown in FIG. _3, a plurality of horizontal period delay circuits CH1 to CH5 which respectively output color difference signals C _{n + 3 to} C _n-2, which are sequentially delayed by 1H (horizontal period) memory after receiving the color difference signal C, and a luminance signal Y are A plurality of horizontal period delay circuits YH1 to YH6 which respectively output luminance signals Y _{n + 3 to} Y _n-3 which are sequentially delayed by 1H in response to the color difference signals C _{n + 3 to} C _n-2. is doing.

The horizontal period delay circuits CH1 to CH5 are
Each is connected to mix circuits 1 to 3
The color difference signals from the horizontal period delay circuits CH1 to CH3 are provided on the path 1.
C_{n + 2}~ C_nHowever, the mix circuit 2 includes a horizontal period delay circuit C
Color difference signal C from H2 to CH4 _{n + 1}~ C_n-1But mix times
The color difference signals from the horizontal period delay circuits CH3 to CH5 are provided on the path 3.
C_n~ C_n-2Are supplied respectively.

In the mix circuit 1, the color difference signal C _{n + 2} is 1
/ 4 (25%), the color difference signal C _{n + 1} is 1/2 (50%),
The three lines are weighted and added at a rate of 1/4 (25%) of the color difference signal C _{n and} the low frequency component C _LPF1 of the color difference signal is output. In the mix circuit 2, the color difference signal C _{n + 1} is 1/4 (25%) and the color difference signal C _n is 1 as in the mix circuit 1.
The three lines are weighted and added at a rate of / 2 (50%) and the color difference signal C _n-1 is ¼ (25%), and the low frequency component C _LPF2 of the color difference signal is output. Further, in the mix circuit 3, as in the mix circuit 1, the color difference signal C _n is ¼ (25
%), The color difference signal C _n-1 is 1/2 (50%), the color difference signal C
Three lines are weighted and added at a rate of _n-2 being ¼ (25%), and the low frequency component C _LPF3 of the color difference signal is output. Then, the low-frequency components C _LPF1 and C _LPF3 of the color difference signals output from the mix circuits 1 and 3 are respectively supplied to the subtracter 4 as the color-difference signal low-frequency component extraction circuit, and the low-frequency components C _BPF of the color difference signal are To be extracted.

The horizontal period delay circuits CH2 to CH4 are also provided.
Are color difference similar line detection circuits (color difference signal similar line
IN detection circuit) 5 to detect this color difference similar line
The circuit 5 includes color difference signals of the horizontal period delay circuits CH2 to CH4.
Issue C_{n + 1}~ C_n-1Is supplied to each of the
Input signal V and horizontal synchronizing signal H, and color difference signal C
_{n + 3}~ C_n-2Find two adjacent lines of similar
It

On the other hand, the horizontal period delay circuits YH1 to YH6 each include an averaging circuit 6 as a luminance signal averaging circuit.
8 to 8 are connected, and these averaging circuits 6 to 8 obtain the average value of the input luminance signals corresponding to the similar lines detected by the color difference similar line detection circuit 5.

That is, the averaging circuit 6 is supplied with the luminance signal Y _{n + 2} from the horizontal period delay circuit YH1 and either the luminance signal Y _{n + 3} or the luminance signal Y _{n + 1} which is switched by the switching circuit 9a. Then, the average value of the similar lines is obtained. The averaging circuit 7 includes a horizontal period delay circuit Y.
The luminance signal Y _n from H3 and either the luminance signal Y _{n + 1} or the luminance signal Y _n-1 which is switched by the switching circuit 9b are supplied to obtain the average value of similar lines. Further, the averaging circuit 8 includes a horizontal period delay circuit YH5.
From the luminance signal Y _n-2 and the luminance signal Y _{n -1} or the luminance signal Y _n-3 which is switched by the switching circuit 9c, and the average value of similar lines is obtained.

In the switching circuits 9a to 9c, the luminance of the lines to which the color difference signals C _{n + 1 to} C _{n-1 of the} horizontal period delay circuits CH2 to CH4 are similar by the color difference signal similar line detection circuit 5, respectively. Switched to select signal.

Mixing circuits 10 to 12 are connected to the averaging circuits 6 to 8, respectively. In the mixing circuit 10, the luminance signal supplied from the averaging circuit 6 is 3/4 (75).
%), The luminance signal supplied from the averaging circuit 7 is 1/4
Average value Y of the luminance signal after weighted addition at a rate of (25%)
Output _LPF1 . In the mix circuit 11, the luminance signal supplied from the averaging circuit 6 is weighted and added at a rate of ¼ (25%), and the luminance signal supplied from the averaging circuit 7 is 3/4 (75%). The average value Y _LPF2 of the luminance signal is output. Further, in the mix circuit 12, the luminance signal supplied from the averaging circuit 7 is weighted and added at a rate of 1/4 (25%), and the luminance signal supplied from the averaging circuit 8 is added at a rate of 3/4 (75%). The average value Y _LPF3 of the luminance signal is output.

The luminance signal Y _n supplied from the horizontal period delay circuit YH3 and the average value Y _LPF2 of the luminance signal output from the mix circuit 11 are input to the subtracter 13 as a luminance signal high frequency component extraction circuit, The subtractor 13 extracts the high frequency component Y _HPF of the average value of the luminance signal. Also, the average value Y _LPF1 of the luminance signal output from the mix circuit 10 and the average value Y of the luminance signal output from the mix circuit 12
_LPF3 is a subtractor 14 as a luminance signal low frequency component extraction circuit.
, And the subtractor 14 extracts the low-frequency component Y _BPF of the average value of the luminance signal.

The subtractor 14 includes an absolute value circuit 15 and a sign.
These absolute value circuits 1 are respectively connected to the generation circuit 17.
5 and the code generation circuit 17 generate the low range of the average value of the luminance signal.
Minute Y _BPFIs supplied, and the absolute value is output from the absolute value circuit 15.
Signal | Y_BPF| Output a signal. Also, the subtractor 1
3 is supplied to the absolute value circuit 16 and the code generation circuit 17, respectively.
Connected to each other, and these absolute value circuit 16 and code generation circuit
17, the high frequency component Y of the average value of the luminance signal_HPFIs supplied,
The absolute value signal from the absolute value circuit 16 is | Y_{H PF}｜
Output a signal. Further, the code generation circuit 17 is described above.
Connected to the subtractor 4 and the color difference signal from the subtractor 4 is reduced.
Region component C_BPFIs supplied. Therefore, the code generation circuit
17 is the low-frequency component C of the color difference signal_BPF, Average value of luminance signal
Low frequency component Y_{B PF}, And high frequency component Y_HPFFrom the product of the signs of
Generate a code.

The subtractor 4 is connected to the absolute value circuit 18,
The low frequency component C _BPF of the color difference signal is input to the absolute value circuit 18 and a | C _BPF | signal which is an absolute value signal is output. This | C _{BP F} | signal is input to the divider 19 as the first calculating means.

On the other hand, | Y output from the absolute value circuit 15
_BPF| The signal is the minimum value described later with respect to the clipping circuit 20.
Input to the selection circuit, and in this clipping circuit 20, the absolute value
Is constant below a certain value so that the value of the issue does not become too small
Clip to value. Output from this clip circuit 20
｜ Y_BPF| The signal is input to the divider 19 and the divider 19
19 | C_BPF| Signal | Y_BPF| Brightness divided by signal
Low frequency component of signal | Y _BPF｜ Low color difference signal to signal
Range component | C_BPF｜ Signal ratio ｜ C_BPF｜ / ｜ Y_{B PF}|
Calculate

This ratio _{│C BPF} │ / _{│Y BPF} │ is inputted to the multiplier 21 as the second calculating means, and the multiplier 21 is also inputted with the _{│Y HPF} │ signal from the absolute value circuit 16, High frequency component of luminance signal | Y _HPF | Signal and above ratio | C _BPF | /
| Y _BPF | high-frequency component correction value of the color difference signal based on | C _BPF
| / | Y _BPF | × | Y _HPF | is calculated.

Then, the high-frequency component correction value of the color difference signal | C
_BPF │ / _{│Y BPF} │ × _{│Y HPF} │ and the | Y _BPF │ signal output from the absolute value circuit 15 are input to the minimum value selection circuit 22, which corrects the high frequency components. Value |
C _BPF | / | Y _BPF | × | Y _HPF | is prevented from becoming an excessive value.

The high frequency component correction value _{│C BPF} │ / _{│Y BPF} │ × _{│Y HPF} │ output from the minimum value selection circuit 22 is
The code generated by the code generation circuit 17 is input to the multiplier 23, and this code is multiplied by the high frequency component correction value | C _BPF | / | Y _BPF | × | Y _HPF | To be done.

Further, the high frequency component correction value _{│C BPF} │ / _{│Y BPF} │ × _{│Y HPF} │ output from the multiplier 23 is input to the adder 24 as an adder circuit, and this adder 24 has The low-frequency component C _LPF2 of the color difference signal is also input from the mix circuit 2,
In the adder 24, the high frequency component correction value | C _BPF | / | Y _BPF | ×
| Y _HPF | and the low-frequency component C _{LPF2 of} the color difference signal are added to obtain the high-frequency-corrected color difference signal.

The output side of the adder 24 has an output switching circuit 25.
Connected to the contact a of the output switching circuit 25.
The contact b or the contact c can be switched. The contact b is connected to the mix circuit 2, while the contact c is connected to the horizontal period delay circuit CH3. When the color difference signal C is the color difference signal of the progressive scanning video signal in the 4: 2: 0 format, the contact a is selected and the high frequency corrected color difference signal output from the adder 24 is transmitted.

On the other hand, when the color difference signal C is the color difference signal of the interlaced scanning video signal in the 4: 2: 0 format,
When the contact b or the contact c is selected, the low frequency component C _LPF2 of the color difference signal output from the mix circuit 2 is transmitted when the contact b is selected, and the color difference signal C _n is selected when the contact c is selected.
To transmit directly.

Here, when the color difference signal C is a color difference signal of a progressive scanning video signal in the 4: 2: 0 format, FIG.
As shown in, the same color difference signal is provided for every two lines.
In this case, the color difference signal similar line detection circuit 5 determines the position of each line (n-3, n-2, ... N + 3) and whether the line is similar to the upper or lower position for 1V period (one screen). (Vertical period), and it is determined whether the lines are similar due to the relationship between the odd lines and the even lines, or whether the lines are similar due to the relationships between the even lines and the odd lines.

That is, in FIG. 2, lines n-2, n-
1, line n, n + 1, line n + 2, n + 3 correspond to color difference signals C _n-2 and C _n-2 , color difference signals C _n and C _n , and color difference signals C _{n + 2} and C _{n + 2} , respectively, and these are the same. It is a dye line. Therefore, in the switching circuit 9a, the luminance signal Y
_{When n + 3} is selected, the luminance signal Y _{n + 3} and the luminance signal Y _{n + 2} are input to the averaging circuit 6, and the average value of both luminance signals is obtained. Further, in the switching circuit 9b, the luminance signal Y _{n + 1} is selected, and the luminance signal Y _{n + 1} and the luminance signal Y _n are input to the averaging circuit 7 to obtain the average value of both luminance signals. Further, in the switching circuit 9c, the luminance signal Y _n-1 is selected and the luminance signal Y _n-1 and the luminance signal Y _n-2 are input to the averaging circuit 8 to obtain the average value of both luminance signals. To be

Then, the color difference similar line detection circuit 5 switches the switching circuit 9a based on the discrimination result in the next V period.
After switching 9c to 9c and selecting a similar line and taking the average value, the high frequency component and the low frequency component of the luminance signal Y are extracted as described above.

As described above, according to the present embodiment, the color difference signal similar line detection circuit 5 detects two similar adjacent lines of the color difference signal C, and the luminance signal Y corresponding to the detected similar line is detected. The average value is acquired by the averaging circuits 6-8. The low-frequency component of the average value of the luminance signal Y is extracted by the subtractor 14, the high-frequency component of the average value of the luminance signal Y is extracted by the subtractor 13, and the low-frequency component of the color difference signal C is extracted by the subtractor 4. To do. Then, the ratio of the low frequency component of the color difference signal C to the low frequency component of the luminance signal Y is calculated by the divider 19, and the high frequency component of the luminance signal Y is multiplied by the high frequency correction component of the color difference signal C based on the ratio. Calculated by the device 21,
The low-frequency component of the color difference signal C and the high-frequency correction component are added by the adder 2
Since the high-frequency-corrected color-difference signal is obtained by addition by 4, the color resolution can be improved without damaging the high-frequency component of the color-difference signal C.

Further, according to the present embodiment, the high frequency component of the luminance signal is used for the video signal of the progressive scanning or the interlaced scanning of the 4: 2: 0 format in which the same color difference signal is obtained for every two lines. It is possible to improve the color resolution in the vertical direction by performing the high-frequency component correction processing of the color difference signal and converting the signal into the pseudo 4: 2: 2 format signal.

Further, according to this embodiment, the output switching circuit 25 can switch the output depending on whether the color difference signal C is the color difference signal of the progressive scanning video signal or the color difference signal of the interlaced scanning video signal. Since this is possible, it is possible to appropriately select whether to transmit the high-frequency-corrected color difference signal or the low-frequency component of the color difference signal.

[0038]

As described above, according to the first aspect of the invention, the color difference signal similar line detection circuit detects two adjacent lines having similar input color difference signals, and the detected similar lines. The average value of the input luminance signal corresponding to is acquired, the ratio of the low frequency component of the input color difference signal to the low frequency component of this input luminance signal is calculated, and the input is performed based on this ratio and the high frequency component of the input luminance signal. Since the high-frequency correction component of the color difference signal is calculated and the low-frequency component of the color difference signal and the high-frequency correction component of the luminance signal are added to obtain the high-frequency corrected color difference signal, the vertical color resolution Can be improved.

According to the invention described in claim 2, since the color difference signal is a color difference signal of a progressive scanning video signal in the 4: 2: 0 format, the color in the vertical direction is the same as the invention described in claim 1. The resolution can be improved.

According to the invention of claim 3, claim 1
Alternatively, in addition to the effect of the invention described in 2, the output can be switched depending on whether the input color difference signal is the color difference signal of the progressive scanning video signal or the color difference signal of the interlaced scanning video signal. It is possible to appropriately select whether to transmit the high-frequency-corrected color difference signal or the low-frequency component of the color difference signal.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a video signal processing device according to the present invention.

FIG. 2 is an explanatory diagram showing a color difference signal of a progressive scanning video signal in the 4: 2: 0 format of FIG.

[Explanation of symbols]

1 to 3 ... Mix circuit 4 ... Subtractor (color difference signal low-frequency component extraction circuit) 5 ... Color difference similar line detection circuit (color difference signal similar line detection circuit) 6 to 8 ... Averaging circuit (luminance signal averaging circuit) 9a ... 9c ... Switching circuits 10-12 ... Mix circuit 13 ... Subtractor (luminance signal high-frequency component extraction circuit) 14 ... Subtractor (luminance signal low-frequency component extraction circuit) 15, 16 ... Absolute value circuit 17 ... Code generation circuit 18 ... Absolute value circuit 19 ... Divider (first calculation means) 20 ... Clip circuit 21 ... Multiplier (second calculation means) 22 ... Minimum value selection circuit 23 ... Multiplier 24 ... Adder (addition circuit) 25 ... Output switching circuit

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroshi Honda             Yamanashi Prefecture Nakatoma-gun Tatomi Town Nishi Hanawa 2680 Shizu Shizu             Oka Pioneer Corporation Kofu Office F term (reference) 5C066 AA11 BA01 CA06 EC11 GA02                       GA05 GA13 GA14 GA28 GB01                       KC11 KD08 KE02 KE03 KE05                       KG01 LA02

Claims (3)

[Claims] 1. A color difference signal similar line detection circuit for detecting two adjacent lines having similar input color difference signals, and a luminance signal averaging circuit for obtaining an average value of input luminance signals corresponding to the detected similar lines. A luminance signal low frequency component extraction circuit for extracting a low frequency component of the average value of the input luminance signal; a luminance signal high frequency component extraction circuit for extracting a high frequency component of the average value of the input luminance signal; A color difference signal low frequency component extraction circuit for extracting a low frequency component of the color difference signal; a first calculation circuit for calculating a ratio of a low frequency component of the input color difference signal to a low frequency component of the input luminance signal; A second arithmetic circuit that calculates a high-frequency correction component of the input color difference signal based on the high-frequency component and the ratio, and a high-frequency correction by adding the low-frequency component and the high-frequency correction component of the input color-difference signal. Color difference signal A video signal processing apparatus characterized by comprising an adding circuit for, a. 2. The video signal processing device according to claim 1, wherein the input color difference signal C is a color difference signal of a progressive scanning video signal in a 4: 2: 0 format. 3. The video signal processing device according to claim 1, wherein when the input color difference signal C is a color difference signal of a progressive scanning video signal in a 4: 2: 0 format, it is output from the adding circuit 24. While transmitting the high-frequency corrected color difference signal,
When the input color difference signal C is a color difference signal of an interlaced scanning video signal in a 4: 2: 0 format, the color difference signal C
An image signal processing device comprising an output switching circuit 25 for transmitting the low-frequency component of