this module allows you to tweak contrast per frequency band. it uses a decimated wavelet transform and variance estimation to shield edges from artifacts. it's essentially unsharp mask (USM) on steroids.
it is intended to affect the texture of the image, not the edges. that is,
high-contrast detail such as hair and silhouettes will remain unaffected by
this module. it works best in scene-referred linear, i.e. before the display
transform in filmcurv for instance.
here is an example where the eq module is used for dehazing and for some
exaggerated contrast in the sky (image a playraw from pixls.us, pull the little
triangle at the bottom to compare):
detail modulate wavelet details at every scale, coarse (left) to fine (right), hold shift to lockstepinputoutput