A method of processing a color digital image having a luminance channel
and one or more chrominance channels to improve the tone scale
characteristics of the image, includes the steps of: producing a control
signal from the one or more chrominance channels; generating a pedestal
signal containing mainly low frequency modulation by filtering the
luminance channel with a spatial filter, whereby the operation of the
spatial filter is modulated by the control signal; and producing a
texture signal by subtracting the pedestal signal from the luminance
channel.