VIDEO SIGNAL PROCESSING APPARATUS AND VIDEO SIGNAL PROCESSING METHOD

• US 20080080790A1
• Filed: 09/26/2007
• Published: 04/03/2008
• Est. Priority Date: 09/27/2006
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Arai, Shin, Hori, Yasuhiro, Sato, Koichi
• Granted Patent: US 8,107,773 B2
• Time in Patent Office: Days
• US Class Current: 382/300
• CPC Class Codes: G09G 2310/0229 De-interlacing
• CPC Class Codes: G09G 3/20 for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
• CPC Class Codes: H04N 7/012 Conversion between an interlaced and a progressive signal for graphics images G09G2310/0229
• CPC Class Codes: H04N 7/0135 involving interpolation processes interpolation-based image scaling G06T3/4007; interpolation for video coding H04N19/587, H04N19/59

Abstract

A video-signal processor includes: a first correlation detector obtaining a correlation value of every symmetric pair of pixels positioned in point-symmetry around an interpolation pixel on an interpolation line interpolated between two real lines; a second correlation detector obtaining a correlation value of every pair of pixels for the symmetric pair of pixels and parallel pair(s) of pixels positioned in a direction parallel to a direction of the symmetric pair of pixels; a correlation-direction deciding unit deciding one of a correlation direction based on the correlation value from the first correlation detector and that based on the correlation value from the second correlation detector as a correlation direction which is a direction of the pair of pixels used for generating the interpolation pixel; and an interpolation pixel generator generating a pixel signal of the interpolation pixel using a pair of pixels based on decision result of the correlation-direction deciding unit.

Claims

1. A video signal processing apparatus, comprising:

a first correlation detecting unit obtaining a correlation value of every symmetric pair of pixels positioned in a point-symmetry, center of which is an interpolation pixel on an interpolation line interpolated between two real lines, the symmetric pair of pixels being positioned on the two real lines of an input video signal respectively;

a second correlation detecting unit obtaining a correlation value of every pair of pixels for the symmetric pair of pixels and one or more parallel pairs of pixels positioned in a direction which is parallel to a direction of the symmetric pair of pixels, the parallel pair of pixels being positioned on the two real lines of the input video signal respectively;

a correlation direction deciding unit deciding any one of a correlation direction based on the correlation value from the first correlation detecting unit and a correlation direction based on the correlation value from the second correlation detecting unit as a correlation direction which is a direction of a pair of pixels used for generating the interpolation pixel; and

an interpolation pixel generating unit generating a pixel signal of the interpolation pixel by using the pair of pixels based on a decision result of the correlation direction deciding unit.

2. The video signal processing apparatus according to claim 1,

wherein the number of the symmetric pairs of pixels, the correlation value of which is obtained by the second correlation detecting unit, is less than the number of the symmetric pairs of pixels, the correlation value of which is obtained by the first correlation detecting unit.

3. The video signal processing apparatus according to claim 1, further comprising,

a horizontal high frequency component detecting unit detecting a horizontal high frequency component of a pair of pixels positioned on the two real lines of the input video signal respectively,

wherein when it is decided based on a detection result by the horizontal high frequency component detecting unit that the symmetric pair of pixels are pixels in a horizontal high frequency component area, the correlation direction deciding unit designates the correlation direction based on the correlation value from the second correlation detecting unit to be a decision result.

4. The video signal processing apparatus according to claim 3,

wherein the number of the symmetric pairs of pixels, the correlation value of which is obtained by the second correlation detecting unit, is less than the number of the symmetric pairs of pixels, the correlation value of which is obtained by the first correlation detecting unit.

5. The video signal processing apparatus according to claim 3,

wherein when it is decided based on a detection result by the horizontal high frequency component detecting unit that the symmetric pair of pixels are pixels in a horizontal high frequency component area, for the correlation value of every symmetric pair of pixels from the second correlation detecting unit, the correlation direction deciding unit calculates the sum of the correlation value of the symmetric pair of pixels and the correlation values of the one or more parallel pairs of pixels positioned in a direction which is parallel to a direction of the symmetric pair of pixels, and designates the correlation direction indicating the symmetric pair of pixels, the sum of the correlation values of which is minimum, to be a decision result.

6. The video signal processing apparatus according to claim 1, further comprising:

a temporary interpolation pixel generating unit generating a temporary interpolation pixel signal by using the pair of pixels of the correlation direction based on the correlation value from the first correlation detecting unit; and

a peripheral pixel selecting unit outputting the pixel signal of the pair of pixels around the interpolation pixel, the pair of pixels being positioned on the two real lines of the input video signal respectively,

wherein when a value of the temporary interpolation pixel signal is a maximum value or a minimum value of the pixel signals from the peripheral pixel selecting unit, the correlation direction deciding unit designates the correlation direction based on the correlation value from the second correlation detecting unit to be a decision result.

7. The video signal processing apparatus according to claim 6,

wherein the number of the symmetric pairs of pixels, the correlation value of which is obtained by the second correlation detecting unit, is less than the number of the symmetric pairs of pixels, the correlation value of which is obtained by the first correlation detecting unit.

8. The video signal processing apparatus according to claim 6,

wherein when a value of the temporary interpolation pixel signal is a maximum value or a minimum value of the pixel signals from the peripheral pixel selecting unit, for the correlation value of every symmetric pair of pixels from the second correlation detecting unit, the correlation direction deciding unit calculates the sum of the correlation value of the symmetric pair of pixels and the correlation values of the one or more parallel pairs of pixels positioned in a direction which is parallel to a direction of the symmetric pair of pixels, and designates the correlation direction indicating the symmetric pair of pixels, the sum of the correlation values of which is minimum, to be a decision result.

9. The video signal processing apparatus according to claim 1,

wherein when a minimum value of the correlation values from the first correlation detecting unit is no less than a first threshold, the correlation direction deciding unit causes the correlation direction based on the correlation values from the first correlation detecting unit to be invalid, and when a minimum value of the correlation values from the second correlation detecting unit is no less than a second threshold which is different from the first threshold, the correlation direction deciding unit causes the correlation direction based on the correlation values from the second correlation detecting unit to be invalid.

10. The video signal processing apparatus according to claim 9,

wherein the number of the symmetric pairs of pixels, the correlation value of which is obtained by the second correlation detecting unit, is less than the number of the symmetric pairs of pixels, the correlation value of which is obtained by the first correlation detecting unit.

11. The video signal processing apparatus according to claim 9,

wherein when a minimum value of the correlation values from the first correlation detecting unit is no less than the first threshold, and a minimum value of the correlation values from the second correlation detecting unit is no less than the second threshold which is different from the first threshold, the correlation direction deciding unit causes the correlation direction indicating the symmetric pair of pixels in a horizontally same position as that of the interpolation pixel to be a decision result.

12. The video signal processing apparatus according to claim 1, comprising:

a horizontal high frequency component detecting unit detecting the horizontal high frequency component of the pair of pixels positioned on the two real lines of the input video signal respectively;

a temporary interpolation pixel generating unit generating a temporary interpolation pixel signal by using the pair of pixels of the correlation direction based on the correlation value from the first correlation detecting unit; and

a peripheral pixel selecting unit outputting the pixel signal of the pair of pixels around the interpolation pixel, the pair of pixels being positioned on the two real lines of the input video signal respectively,

wherein when it is decided based on a detection result by the horizontal high frequency component detecting unit that the symmetric pair of pixels are pixels in the horizontal high frequency component area, and when a value of the temporary interpolation pixel signal is a maximum value or a minimum value of the pixel signals from the peripheral pixel selecting unit and also a minimum value of the correlation values from the second correlation detecting unit is smaller than a prescribed threshold, the correlation direction deciding unit designates the correlation direction based on the correlation value from the second correlation detecting unit to be a decision result, and when a value of the temporary interpolation pixel signal is a maximum value or a minimum value of the pixel signals from the peripheral pixel selecting unit and also the minimum value of the correlation values from the second correlation detecting unit is no less than the prescribed threshold, the correlation direction deciding unit designates the correlation direction indicating the symmetric pair of pixels in a horizontally same position as that of the interpolation pixel to be a decision result, and in other cases, the correlation direction deciding unit designates the correlation direction based on the correlation value from the first correlation detecting unit to be a decision result.

13. The video signal processing apparatus according to claim 12,

wherein the number of the symmetric pairs of pixels, the correlation value of which is obtained by the second correlation detecting unit, is less than the number of the symmetric pairs of pixels, the correlation value of which is obtained by the first correlation detecting unit.

14. The video signal processing apparatus according to claim 12,

wherein when the correlation direction based on the correlation value from the second correlation detecting unit is designated to be a decision result, for the correlation value of every symmetric pair of pixels from the second correlation detecting unit, the correlation direction deciding unit calculates the sum of the correlation value of the symmetric pair of pixels and the correlation value of the one or more parallel pairs of pixels positioned in a direction which is parallel to a direction of the symmetric pair of pixels, and designates the correlation direction indicating the symmetric pair of pixels, the sum of the correlation values of which is minimum, to be a decision result.

15. A video signal processing apparatus, comprising:

a first correlation detecting unit obtaining a correlation value of every symmetric pair of pixels positioned in a point-symmetry, center of which is an interpolation pixel on an interpolation line interpolated between two real lines, the symmetric pair of pixels being a pair of pixels positioned on the two real lines of an input video signal respectively, and detecting a direction indicated by the symmetric pair of pixels, the correlation value of which is minimum, as a first correlation direction candidate;

a second correlation detecting unit obtaining the correlation value of every pair of pixels for the symmetric pair of pixels and one or more parallel pairs of pixels positioned in a direction which is parallel to a direction of the symmetric pair of pixels, the parallel pair of pixels being a pair of pixels positioned on the two real lines of the input video signal respectively, for every symmetric pair of pixels, calculating the sum of the correlation value of the symmetric pair of pixels and the correlation values of the one or more parallel pairs of pixels positioned in a direction which is parallel to a direction of the symmetric pair of pixels, and detecting a correlation direction indicated by the symmetric pair of pixels, the sum of the correlation values of which is minimum, as a second correlation direction candidate;

a correlation direction deciding unit deciding any one of a first correlation direction candidate and a second correlation direction candidate as a correlation direction which is a direction of the pair of pixels used for generating the interpolation pixel; and

an interpolation pixel generating unit generating a pixel signal of the interpolation pixel by using the pair of pixels based on a decision result of the correlation direction deciding unit.

16. A video signal processing method, comprising:

obtaining a correlation value of every symmetric pair of pixels positioned in a point-symmetry, center of which is an interpolation pixel on an interpolation line interpolated between two real lines, the symmetric pair of pixels being a pair of pixels positioned on the two real lines of an input video signal respectively, and outputting as a first correlation value group;

obtaining the correlation value of every pair of pixels for the symmetric pair of pixels and one or more parallel pairs of pixels positioned in a direction which is parallel to a direction of the symmetric pair of pixels, the parallel pair of pixels being a pair of pixels positioned on the two real lines of the input video signal respectively, and outputting as a second correlation value group;

deciding any one of a correlation direction based on the first correlation value group and a correlation direction based on the second correlation value group as a correlation direction which is a direction of the pair of pixels used for generating the interpolation pixel; and

generating a pixel signal of the interpolation pixel by using the pair of pixels based on the decision result.

17. The video signal processing method according to claim 16, further comprising:

detecting a horizontal high frequency component of a pair of pixels positioned on the two real lines of the input video signal respectively; and

designating the correlation direction based on the second correlation value group to be a decision result when it is decided that the symmetric pair of pixels included in the correlation direction based on the first correlation value group is a pixel in a horizontal high frequency component area.

18. The video signal processing method according to claim 16, further comprising:

generating a temporary interpolation pixel signal by using a pair of pixels of the correlation direction based on the first correlation value group; and

designating the correlation direction based on the second correlation value group to be a decision result when the temporary interpolation pixel signal is a maximum value or a minimum value of pixel signals of pairs of pixels around the interpolation pixel, the pairs of pixels being positioned on the two real lines of the input video signal respectively.

19. The video signal processing method according to claim 16, further comprising:

causing the correlation direction based on the first correlation value group to be invalid when the correlation direction is decided, and a minimum value of the first correlation value group is no less than a first threshold; and

causing the correlation direction based on the second correlation value group to be invalid when the correlation direction is decided, and a minimum value of the second correlation value group is no less than a second threshold which is different from the first threshold.

20. The video signal processing method according to claim 16, further comprising:

detecting the horizontal high frequency component of the pair of pixels positioned on the two real lines of the input video signal respectively;

deciding the correlation direction based on the correlation value from the second correlation detecting unit when the symmetric pairs of pixels included in the correlation direction based on the first correlation value group are pixels in the horizontal high frequency component area, and when the temporary interpolation pixel signal generated by using the pair of pixels of the correlation direction based on the first correlation value group is a maximum value or a minimum value of the pixel signals of the pairs of pixels around the interpolation pixel, the pair of pixels being positioned on the two real lines of the input video signal respectively, and also the minimum value of the second correlation value group is smaller than a prescribed threshold;

deciding a direction indicating the symmetric pair of pixels at a horizontally same position as that of the interpolation pixel as the correlation direction when the temporary interpolation pixel signal is a maximum value or a minimum value of the pixel signal of the pair of pixels around the interpolation pixel, the pairs of pixels being positioned on the two real lines of the input video signal respectively, and also the minimum value of the second correlation value group is no less than the prescribed threshold; and

designating the correlation direction based on the first correlation value group to be a decision result in other cases.