Sigmoid creates a filter that changes the contrast of an image using a sigmoidal function and returns the adjusted image. It's a non-linear contrast change useful for photo adjustments as it preserves highlight and shadow detail. The midpoint parameter is the midpoint of contrast that must be between 0 and 1, typically 0.5. The factor parameter indicates how much to increase or decrease the contrast, typically in range (-10, 10). If the factor parameter is positive the image contrast is increased otherwise the contrast is decreased.


g := gift.New(
	gift.Sigmoid(0.5, 3.0),
dst := image.NewRGBA(g.Bounds(src.Bounds()))
g.Draw(dst, src)

Sigmoid is referenced in 2 repositories