Local tone mapping of processed image

1 . An image processing circuit, comprising:

a local tone mapping (LTM) circuit configured to receive a processed image generated from an input image, the LTM circuit comprising:

a first circuitry to determine an input color component value for a color component of a pixel in a version of the processed image having a color component value for the color component of the pixel in the version of the processed image;

a second circuitry to determine an output color component value for the color component of the pixel in the version of the processed image, based on mapping of coordinates of pixels in the processed image to coordinates of pixels in the input image;

a third circuitry to determine a gain value for the pixel in the version of the processed image as a ratio of the output color component value relative to the input color component value; and

a fourth circuitry to adjust the color component value for the color component of the pixel in the version of the processed image using the gain value to generate an adjusted color component value for the color component of the pixel in an output image.

2 . The image processing circuit of claim 1 , wherein the LTM circuit further comprises:

a fifth circuitry to perform color space conversion of pixels in the processed image to generate a color converted version of the processed image; and

a sixth circuitry to determine an input luma component value for a pixel in the color converted version of the processed image.

3 . The image processing circuit of claim 2 , wherein the LTM circuit further comprises:

a seventh circuitry to determine, for the pixel in the color converted version and based on the mapping, a corresponding subset of LTM curves in a look-up table (LUT);

an eighth circuitry to provide the input luma component value for the pixel in the color converted version as an input entry to each LTM curve of the corresponding subset of LTM curves; and

a ninth circuitry to output interpolated luma values for the pixel in the color converted version generated based on the input entry to each LTM curve of the corresponding subset of LTM curves.

4 . The image processing circuit of claim 3 , wherein the LTM circuit further comprises a tenth circuitry to perform spatial interpolation of the interpolated luma values to generate the output color component value for the pixel, the output color component value representing an output luma component value for the pixel in the color converted version.

5 . The image processing circuit of claim 4 , wherein the LTM circuit further comprises an eleventh circuitry to determine the gain value for the pixel as a ratio of the output luma component value relative to the input luma component value.

6 . The image processing circuit of claim 3 , wherein the LTM circuit further comprises an eleventh circuitry to perform bilinear interpolation of the interpolated luma values to generate the output color component value for the pixel.

7 . The image processing circuit of claim 1 , wherein the LTM circuit further comprises a fifth circuitry to apply at least one of global tone adjustment, black-level compensation, and gamma correction on the output color component value for the pixel to generate a corrected color component value for the pixel.

8 . The image processing circuit of claim 7 , wherein the LTM circuit further comprises a sixth circuitry to determine the gain value for the pixel further based on the corrected color component value.

9 . The image processing circuit of claim 1 , further comprising:

a fifth circuitry to generate information about the mapping of coordinates of pixels in the processed image to coordinates of pixels in the input image; and

a sixth circuitry to provide the generated information about the mapping to the LTM circuit.

10 . The image processing circuit of claim 1 , further comprising a fifth circuitry to output the processed image as a plurality of processed tiles that are passed to the LTM circuit.

11 . The image processing circuit of claim 1 , wherein the LTM circuit further comprises a fifth circuitry to perform color space conversion of pixels in the output image to generate a color converted version of the output image having a same format as the input image.

12 . A method for image processing, comprising:

determining an input color component value for a color component of a pixel in a version of a processed image, wherein the processed image is based on an input image;

determining an output color component value for the color component of the pixel, based on mapping of coordinates of pixels in the version of the processed image to coordinates of pixels in the input image that is used to generate the processed image;

determining a gain value for the pixel as a ratio of the output color component value relative to the input color component value; and

adjusting color component values for color components of the pixel using the gain value to generate adjusted color component values for the color components of the pixel in an output image.

13 . The method of claim 12 , further comprising:

performing color space conversion of pixels in the processed image to generate a color converted version of the processed image; and

determining an input luma component value for a pixel in the color converted version of the processed image.

14 . The method of claim 13 , further comprising:

determining, for the pixel in the color converted version based on the mapping, a corresponding subset of local tone mapping (LTM) curves in a look-up table (LUT);

providing the input luma component value for the pixel in the color converted version as an input entry to each LTM curve of the corresponding subset of LTM curves; and

outputting interpolated luma values for the pixel in the color converted version generated based on the input entry to each LTM curve of the corresponding subset of LTM curves.

15 . The method of claim 14 , further comprising:

performing spatial interpolation of the interpolated luma values to generate the output color component value for the pixel, the output color component value representing an output luma component value for the pixel in the color converted version; and

determining the gain value for the pixel as a ratio of the output luma component value relative to the input luma component value.

16 . The method of claim 14 , further comprising:

performing bilinear interpolation of the interpolated luma values to generate the output color component value for the pixel.

17 . The method of claim 12 , further comprising:

applying at least one of global tone adjustment, black-level compensation, and gamma correction on the output color component value for the pixel to generate a corrected color component value for the pixel; and

determining the gain value for the pixel further based on the corrected color component value.

18 . The method of claim 12 , further comprising:

performing color space conversion of pixels in the output image to generate a color converted version of the output image having a same format as the input image.

19 . An electronic device, comprising:

an image sensor configured to capture an input image; and

a local tone mapping (LTM) circuit configured to receive a processed image based on the input image, the LTM circuit comprising:

a first circuitry to determine an input color component value for a color component of a pixel in a version of the processed image;

a second circuitry to determine an output color component value for the color component of the pixel, based on mapping of coordinates of pixels in the processed image to coordinates of pixels in the input image on which the processed image is based;

a third circuitry to determine a gain value for the pixel as a ratio of the output color component value relative to the input color component value; and

a fourth circuitry to adjust color component values for color components of the pixel using the gain value to generate adjusted color component values for the color components of the pixel in an output image.

20 . The electronic device of claim 19 , wherein the LTM circuit further comprises:

a fifth circuitry to perform color space conversion of pixels in the processed image to generate a color converted version of the processed image;

a sixth circuitry to determine an input luma component value for a pixel in the color converted version of the processed image;

a seventh circuitry to determine, for the pixel in the color converted version based on the mapping, a corresponding subset of LTM curves in a look-up table (LUT);

an eighth circuitry to provide the input luma component value for the pixel in the color converted version as an input entry to each LTM curve of the corresponding subset of LTM curves;

a ninth circuitry to output interpolated luma values for the pixel in the color converted version generated based on the input entry to each LTM curve of the corresponding subset of LTM curves; and

a tenth circuitry to perform spatial interpolation of the interpolated luma values to generate the output color component value for the pixel, the output color component value representing an output luma component value for the pixel in the color converted version.