img contrast

Enhances the differences in intensity between the lighter and darker tones of an image. There are three methods available for contrast adjustment; default, linear or sigmoidal.

--factor <n>

Factor to shift contrast by (default: 1.0).

--midpoint <n>

Set where midtones fall in image (default: 0.5).

--linear

Use a linear function

--sigmoidal

Use a sigmoidal function