This effect was generated in Filter Forge, a Photoshop plugin that allows you to create your own filters.
This filter provides an easy way to increase the midtone contrast of an image. For example you can emphasize (or deemphasize) detail in the midtones while leaving shadows and highlights untouched.
In Photoshop, similar results can be achieved with the curves command but the procedure is complicated.
Available color models are:
1: HSY – 2: HLS – 3: HSB – 4: Lab
midtone contrast tone tonal width curve gain posterize uber zev