Correcting chrominance values based onTone-mapped luminance values

摘要

A tone mapping unit applies tone mapping to a block of pixel values. In each of a plurality of iterations, one or more lines of pixel values are processed based on information relating to pixel values of at least one previous line of the block which have been processed in at least one previous iteration. The information is used to determine one or more tone mapping relationships which is/are used to map the pixel values of the current line to tone-mapped pixel values. Furthermore, the information is updated based on the pixel values of the current line and stored for use in processing pixel values of a subsequent line of pixel values of the block in a subsequent iteration.

主权项

1. A method of correcting input chrominance values of pixels to determine corrected chrominance values for the pixels based on tone-mapped luminance values which have been determined by applying tone mapping to input luminance values of the pixels, the method comprising:
determining candidate corrected chrominance values for the pixels based on the input chrominance values, the input luminance values and the tone-mapped luminance values, such that for each of the pixels, a first saturation determined from the input luminance value and the input chrominance value has a predetermined relationship to a second saturation determined from the tone-mapped luminance value and the candidate corrected chrominance value; determining confidence weightings which indicate confidences in the respective candidate corrected chrominance values, wherein the confidence weightings are determined in dependence on the input luminance values of the respective pixels; and using the determined confidence weightings to compute, for each of the pixels, a weighted combination of the respective candidate corrected chrominance value and the respective input chrominance value, thereby determining the corrected chrominance values for the pixels.