Colour correction

Abstract

Digital image processing apparatus for applying pixel-based colour correction to a hue-saturation-based polar representation of pixels of an input image to generate an output image comprises colour correction logic arranged to provide a colour mapping operation defined by a hue alteration amount and a key value associated with each pixel; the colour correction logic comprising: hue modifying logic for adding a proportion of the hue alteration amount to the hue of each pixel of the input image, the proportion depending on the key value associated with that pixel; and saturation modifying logic for modifying the saturation of each pixel in dependence on the hue alteration amount and the key value for that pixel, such that for a key value indicating that only a fraction of the hue alteration amount should be applied to a current pixel, the saturation of that pixel is also modified so that, when expressed with respect to a rectangular chrominance-based colour space, the pixel is moved to a position in that colour space substantially lying on a straight line between the original pixel position and the position that the pixel would occupy if the full hue alteration amount were applied.

Dependencies are inferred from the claim text.