Circuit for correcting lateral chromatic abberation

Patent metadata

Field	Value
Publication number	US-11863889-B2
Application number	US-202217734576-A
Country	US
Kind code	B2
Filing date	May 2, 2022
Priority date	Apr 14, 2020
Publication date	Jan 2, 2024
Grant date	Jan 2, 2024

Abstract

Embodiments relate to lateral chromatic aberration (LCA) recovery of raw image data generated by image sensors. A chromatic aberration recovery circuit performs chromatic aberration recovery on the raw image data to correct the resulting LCA in the full color images using pre-calculated offset values of a subset of colors of pixels.

First claim

The invention claimed is:

1. An image processor comprising:
a correction circuit configured to receive pixel values of pixels of a color in a raw input image data, and generate corrected versions of the pixel values by performing interpolation of subsets of the pixels of the color in a plurality of directions using a plurality of different sets of interpolation coefficients, each set of the plurality of different sets of interpolation coefficients associated with a corresponding direction from the plurality of directions, and each set of the plurality of different sets of interpolation coefficients including offset values representing distances from the pixels to corresponding virtual pixels in the corresponding direction where the corresponding virtual pixels have pixel values that are identical to the pixel values of the pixels in the raw input image data absent lateral chromatic aberrations, wherein the corrected versions of the pixel values are included as part of a corrected raw image data; and
a memory coupled to the correction circuit, the memory configured to store one or more lookup tables that include the plurality of different sets of interpolation coefficients.

2. The image processor of claim 1 , wherein the correction circuit comprises:
a first correction circuit configured to:
perform interpolation of pixel values of a first subset of pixels of the color arranged in a first direction from the plurality of directions using one or more first interpolation coefficients included in a first set of interpolation coefficients from the plurality of different sets of interpolation coefficients to generate first corrected versions of the pixel values, the one or more first interpolation coefficients corresponding to first offset values representing first distances from the pixels to the corresponding virtual pixels in the first direction; and

a second correction circuit configured to:
receive the first corrected versions; and
generate second corrected versions of the pixel values by performing interpolation of the first corrected versions of the pixel values of second subset of pixels of the color arranged in a second direction from the plurality of directions using one or more second interpolation coefficients included in a second set of interpolation coefficients from the plurality of different sets of interpolation coefficients, the one or more second interpolation coefficients corresponding to second offset values representing second distances from the pixels in the raw input image data to the corresponding virtual pixels in the second direction.

3. The image processor of claim 2 , wherein the corrected versions of the pixel values that are included as part of the corrected raw image data include the second corrected versions of the pixel values.

4. The image processor of claim 2 , further comprising:
an offset interpolator circuit configured to determine the first offset values and the second offset values of the pixels in the raw input image data by bilateral interpolating predetermined first offset values and predetermined second offset values associated with grid points neighboring the pixels in the raw input image data.

5. The image processor of claim 4 , wherein the one or more lookup tables include:
a first phase look-up table configured to store the first set of interpolation coefficients indexed by the first distances or first parameters derived from the first distances;
a second phase look-up table configured to store the second set of interpolation coefficients indexed by the second distances or second parameters derived from the second distances; and
an offset look-up table configured to store the predetermined first offset values and the predetermined second offset values associated with the grid points.

6. The image processor of claim 1 , wherein each of the raw input image data and the corrected raw image data is in a Bayer pattern.

7. The image processor of claim 2 , wherein the first direction is a vertical direction and the second direction is a horizontal direction.

8. The image processor of claim 7 , wherein a first corrected version of a pixel value for a pixel in the raw input image data is generated by interpolating pixel values for a number of pixels in a same column as the pixel, and a second corrected version of the pixel value for the pixel is generated by interpolating first corrected versions of pixel values for the same number of pixels in a same row as the pixel.

9. The image processor of claim 1 , wherein the received pixel values include pixel values of pixels in colors of red, green, and blue, and wherein the pixel values of pixels of two of the colors are updated by the correction circuit, and pixel values of pixels of a remaining one of the colors is not updated by the correction circuit.

10. The image processor of claim 1 , wherein the color is blue or red, and wherein pixel values of green pixels are not updated by the correction circuit.

11. The image processor of claim 2 , wherein the interpolation performed by the first correction circuit uses a first function defined by the one or more first interpolation coefficients, and the second correction circuit uses a second function defined by the one or more second interpolation coefficients.

12. A method comprising:
receiving pixel values of pixels of a color in a raw input image data; and
generating corrected versions of the pixel values by performing interpolation of subsets of the pixels of the color in a plurality of directions using a plurality of different sets of interpolation coefficients, each set of the plurality of different sets of interpolation coefficients associated with a corresponding direction from the plurality of directions, and each set of the plurality of different sets of interpolation coefficients including offset values representing distances from the pixels to corresponding virtual pixels in the corresponding direction where the corresponding virtual pixels have pixel values that are identical to the pixel values of the pixels in the raw input image data absent lateral chromatic aberrations,
wherein the corrected versions of the pixel values are included as part of a corrected raw image data.

13. The method of claim 12 , wherein generating the corrected versions of the pixel values comprises:
performing interpolation of pixel values of a first subset of pixels of the color arranged in a first direction from the plurality of directions using one or more first interpolation coefficients included in a first set of interpolation coefficients from the plurality of different sets of interpolation coefficients to generate first corrected versions of the pixel values, the one or more first interpolation coefficients corresponding to first offset values representing first distances from the pixels to the corresponding virtual pixels in the first direction; and
generating second corrected versions of the pixel values by performing interpolation of the first corrected versions of the pixel values of second subset of pixels of the color arranged in a second direction from the plurality of directions using one or more second interpolation coefficients included in a second set of interpolation coefficients from the plurality of different sets of interpolation coefficients, the one or more second interpolation coefficients corresponding to second offset values representing second distances from the pixels in the raw input image data to the corresponding virtual pixels in the second direction.

14. The method of claim 13 , further comprising:
determining the first offset values and the second offset values of the pixels in th

Assignees

• Apple Inc

Inventors

• Wu Chihsin
• Pope David R

Classifications

• H04N25/611 Primary

  Correction of chromatic aberration · CPC title

• G06T5/006

  Physics · mapped topic

• H04N9/646

  for image enhancement, e.g. vertical detail restoration, cross-colour elimination, contour correction, chrominance trapping filters · CPC title

• H04N25/68

  applied to defects · CPC title

• G06T2207/10024

  Color image · CPC title