auto          : Auto Color Correction.
bw            : Black and White.
bcg           : Brighness / Contrast / Gamma.
cb            : Color Balance Correction.
curves        : Histogram Curves Correction.
decorate      : Decorative Effects.
fx            : Special Effects.
greystoration : CImg library interface for Greystoration filter.
hsl           : Hue / Saturation / Lightness.
icc           : Color Management.
levels        : Histogram Levels Correction.
lens          : Misc lens correction filters.
lc            : Local Contrast (LDR Tonemapping).
nr            : Wavelets Noise Reduction.
sharp         : Sharp / Unsharp Mask / Refocus
transform     : Change Image Geometry.
wb            : White Balance.
