Suppression of noise amplification during colour correction

This paper relates to correcting colours in digital photography. Three low pass filters are used to prevent noise amplification during colour correction. It is well known that a straightforward application of a low pass filter reduces the sharpness of an image. The filtering is applied in a non-conventional way which naturally compensates for the blur introduced by filtering. This compensation is achieved by combining data from all the colour channels, thus preserving the original sharpness of the image. This method is particularly useful, but not limited to, CMOS image sensor based digital cameras