An
image processing apparatus operates to process
signal samples representative of at least part of a color
video image to produce legal
color signal samples representative of a legal color version of the image. The apparatus comprises an over sampling processor which operates to generate an over sampled version of the input
signal samples by generating at least one extra
signal sample for each base input signal sample, an adjustment factor generator, which operates to generate a plurality of adjustment factors which when combined with the input signal samples have an effect of converting illegal color pixels of the
color image into legal color pixels, a color legalizer coupled to the adjustment factor generator, which operates to combine the adjustment factors with the input signal samples to produce the legalized
color signal samples in an over sampled form, an anti-
aliasing processor coupled to the color legalizer, which operates to filter selectively the over sampled version of the legalized
color signal samples with an anti-
aliasing filter in dependence upon whether the legalized color signal samples have changed with respect to the input signal samples and if the legalized color signal samples have not changed, bypassing the filter, and a decimating processor coupled to the color legalizer which operates to decimate the filtered legalised color signal samples to produce legalized signal samples having a sampling rate corresponding to that of the base input signal samples. The anti-
aliasing processor filters the legalised color signal samples by selecting the base legalized color signal samples corresponding to the base input signal sample, where neither the base or the associated extra color signal samples have changed with respect to the input signal samples.