Pixel Interpolation Method

• US 20070126885A1
• Filed: 12/01/2005
• Published: 06/07/2007
• Est. Priority Date: 12/01/2005
• Status: Active Grant

• Current Assignee: Megachips Corporation
• Original Assignee: Megachips LSI Solutions Incorporated (Megachips Corporation)
• Inventors: Hasegawa, Hiromu
• Granted Patent: US 7,551,214 B2
• Time in Patent Office: Days
• US Class Current: 348/222.100
• CPC Class Codes: G06T 3/4015 Image demosaicing, e.g. colour filter arrays [CFA] or Bayer patterns
• CPC Class Codes: H04N 23/12 with one sensor only
• CPC Class Codes: H04N 23/843 Demosaicing, e.g. interpolating colour pixel values
• CPC Class Codes: H04N 25/134 based on three different wavelength filter elements

Abstract

Correlation values in the vertical direction, horizontal direction and two diagonal directions are obtained in a pixel signal of RGB Bayer pattern. The correlation values are calculated using G signals. Between a first pair of the vertical and horizontal directions and a second pair of the two diagonal directions, one pair having a greater correlation difference is selected. Then, a direction having a stronger correlation is selected in the selected pair having a greater correlation difference, and pixel interpolation is performed in the selected direction. Alternatively, pixel interpolation is performed following assignment of weights in two directions of the selected pair having a greater correlation difference in accordance with the proportion of their correlations.

Claims

1. A pixel interpolation method comprising:

a first step of inputting pixel data of a predetermined color space;

a second step of obtaining a correlation of a pixel present in a first direction, a correlation of a pixel present in a second direction perpendicular to said first direction, a correlation of a pixel present in a third direction different from said first and second directions and a correlation of a pixel present in a fourth direction perpendicular to said third direction, using neighboring pixels around a target pixel; and

a third step of performing pixel interpolation at said target pixel in at least one of said first to fourth directions using said four correlations in said first to fourth directions.

2. The pixel interpolation method according to claim 1, wherein

said third step includes the step of evaluating correlations of a peripheral region of said target pixel using said four correlations in said first to fourth directions, thereby performing said pixel interpolation at said target pixel in at least one of said first to fourth directions judged that said correlation is strong.

3. The pixel interpolation method according to claim 2, wherein

said third step includes the step of performing said pixel interpolation in at least one direction included in a pair of directions having a greater correlation difference between a pair of said first and second directions and a pair of said third and fourth directions.

4. The pixel interpolation method according to claim 3, wherein

said third step includes the step of performing pixel interpolation only in a direction having the strongest correlation between directions included in said pair having a greater correlation difference.

5. The pixel interpolation method according to claim 3, wherein

said third step includes the step of assigning weights in respective directions included in said pair having a greater correlation difference in accordance with a proportion of said correlations, thereby performing said pixel interpolation.

6. The pixel interpolation method according to claim 1, wherein

said third step includes the step of assigning weights in said first to fourth directions in accordance with a proportion of said correlations, thereby performing said pixel interpolation.

7. The pixel interpolation method according to claim 1, wherein

said pixel data of said predetermined color space contains data having pixels of respective color components included in said predetermined color space arrayed in a Bayer pattern.

8. The pixel interpolation method according to claim 1, wherein

said first direction is one of a vertical direction and a horizontal direction, and

said second direction is a direction inclined at 45 degrees relative to the vertical direction.

9. The pixel interpolation method according to claim 1, wherein

said second step includes the step of obtaining each of said correlations for a G signal when said pixel data is of an RGB color space.

10. The pixel interpolation method according to claim 1, wherein

said second step includes the step of obtaining each of said correlations for a luminance signal when said pixel data is of a predetermined color space containing the luminance signal.