Pixel defect correction device
A point defect and a line defect in a captured image resulting due to an imaging element defect in a digital camera are interpolated. A defect correction circuit of a digital camera simultaneously corrects a point flaw, a vertical line flaw, and a horizontal line flaw in a captured image. In consideration of cases in which a point flaw and a vertical line flaw are present adjacent to each other, the defect correction circuit executes predetermined difference calculations using pixels surrounding a target pixel to be corrected and determines an interpolation pattern based on a comparison of magnitude among the difference calculation values. The defect correction circuit also selects, for interpolation, an interpolation pattern from among interpolation patterns prepared in advance based on an adjacent pattern of the point flaw and line flaw. The adjacent pattern is detected by a defect decode circuit 78.
1. A pixel defect correction circuit which corrects a point defect and a line defect of a plurality of pixels arranged along a horizontal direction and a vertical direction, the pixel defect correction circuit comprising:
a unit which detects presence and a position of a point defect and a line defect;
a unit which corrects a point defect pixel by calculating a pixel value of the point defect pixel from pixel values of surrounding pixels which are adjacent to the point defect pixel;
a unit which calculates a first difference value between pixel values of an upper-right pixel and a lower-left pixel which are adjacent to a target pixel to be corrected within a line defect pixel, a second difference value between pixel values of an upper-left pixel and a lower-right pixel which are adjacent to the target pixel, a third difference value between a sum of the pixel values of the upper-left pixel and the lower-left pixel and a sum of the pixel values of the upper-right pixel and the lower-right pixel, and a fourth difference value between a sum of the pixel values of the upper-left pixel and the upper-right pixel and a sum of the pixel values of the lower-left pixel and the lower-right pixel, and
a unit which corrects the line defect pixel by calculating a pixel value of the target pixel from at least one of the pixel values of the upper-right pixel, the lower-right pixel, the upper-left pixel, and the lower-left pixel using a correction pattern corresponding to a relationship in magnitude of the first difference value, the second difference value, the third difference value, and the fourth difference value.
2. A pixel defect correction circuit according to claim 1 , wherein
the target pixel is a G pixel in a Bayer arrangement.
3. A pixel defect correction circuit according to claim 2 , wherein
when the G pixels in the Bayer arrangement are Gij, R pixels in the Bayer arrangement are Rij, B pixels in the Bayer arrangement are Bij (wherein i and j are integers greater than or equal to 0), and the target pixel is G 23 , the calculating unit calculates:
the first difference value=G 14 −G 32 ;
the second difference value=G 12 −G 34 ;
the third difference value=G 12 +G 32 −G 14 −G 34 ; and
the fourth difference value=G 12 +G 14 −G 32 −G 34 .
4. A pixel defect correction circuit according to claim 1 , wherein
the correcting unit simultaneously corrects a point defect pixel and a line defect pixel in parallel.
5. A pixel defect correction circuit according to claim 1 , wherein
the correcting unit simultaneously corrects a point defect pixel, a vertical line defect pixel, and a horizontal line defect pixel in parallel.
6. A pixel defect correction circuit according to claim 5 , wherein
the correcting unit simultaneously corrects an R pixel, a G pixel, and a B pixel in parallel.
7. A pixel defect correction circuit which corrects a point defect and a line defect of a plurality of pixels arranged along a horizontal direction and a vertical direction, the pixel defect correction circuit comprising:
a unit which detects presence and a position of a point defect and a line defect;
a unit which corrects a point defect pixel by calculating a pixel value of the point defect pixel from pixel values of surrounding pixels which are adjacent to the point defect pixel;
a unit which calculates a first difference value between pixel values of a horizontal direction pixel and an upper-left pixel and a lower-right pixel which are adjacent to a target pixel to be corrected within a line defect pixel, a second difference value between pixel values of the horizontal direction pixel and an upper-right pixel and a lower-left pixel which are adjacent to the target pixel, and a third difference value between pixel values of the horizontal direction pixel and a left pixel and a right pixel which are adjacent to the target pixel; and
a unit which corrects a vertical line defect pixel by calculating a pixel value of the target pixel from at least one of the pixel values of the upper-right pixel, the lower-right pixel, the upper-left pixel, and the lower-left pixel using a correction pattern corresponding to a relationship in magnitude of the first difference value, the second difference value, and the third difference value.
8. A pixel defect correction circuit according to claim 7 , wherein
the target pixel is an R pixel or a B pixel in a Bayer arrangement.
9. A pixel defect correction circuit according to claim 7 , wherein
the target pixel is an R pixel or a B pixel in a Bayer arrangement, and
when G pixels in the Bayer arrangement are Gij, R pixels in the Bayer arrangement are Rij, B pixels in the Bayer arrangement are Bij (wherein i and j are integers greater than or equal to 0), and the target pixel is R 22 , the calculating unit calculates:
the first difference value=G 21 *2+G 23 *2−G 01 −G 10 −G 34 −G 43 ;
the second difference value=G 21 *2+G 23 *2−G 03 −G 14 −G 30 −G 41 ; and
the third difference value=G 21 *2+G 23 *2G 10 −G 30 −G 14 −G 34 .
10. A pixel defect correction circuit which corrects a point defect and a line defect of a plurality of pixels arranged along a horizontal direction and a vertical direction, the pixel defect correction circuit comprising:
a unit which detects presence and a position of a point defect and a line defect;
a unit which corrects a point defect pixel by calculating a pixel value of the point defect pixel from pixel values of surrounding pixels which are adjacent to the point defect pixel;
a unit which calculates a first difference value between pixel values of a vertical direction pixel and an upper-left pixel and a lower-right pixel which are adjacent to a target pixel to be corrected within a line defect pixel, a second difference value between pixel values of the vertical direction pixel and an upper-right pixel and a lower-left pixel which are adjacent to the target pixel, and a third difference value between pixel values of the vertical direction pixel and a left pixel and a right pixel which are adjacent to the target pixel; and
a unit which corrects a horizontal line defect pixel by calculating a pixel value of the target pixel from at least one of the pixel values of the upper-right pixel, the lower-right pixel, the upper-left pixel, and the lower-left pixel using a correction pattern corresponding to a relationship in magnitude among the first difference value, the second difference value, and the third difference value.
11. A pixel defect correction circuit according to claim 10 , wherein
the target pixel is an R pixel or a B pixel in a Bayer arrangement; and
when G pixels in the Bayer arrangement are Gij, R pixels in the Bayer arrangement are Rij, B pixels in the Bayer arrangement are Bij (wherein i and j are integers greater than or equal to 0), and the target pixel is R 22 , the calculating unit calculates:
the first difference value=G 12 *2+G 32 *2−G 01 −G 10 −G 34 −G 43 ;
the second difference value=G 12 *2+G 32 *2−G 03 −G 14 −G 30 −G 41 ; and
the third difference value=G 12 *2+G 32 *2−G 10 −G 30 −G 14 −G 34 .
12. A pixel defect correction circuit according to claim 10 wherein:
the target pixel is an R pixel or a B pixel in a Bayer arrangement.