adjust-sigmoid

adjust_sigmoid

skimage.exposure.adjust_sigmoid(image, cutoff=0.5, gain=10, inv=False) [source]

Performs Sigmoid Correction on the input image.

Also known as Contrast Adjustment. This function transforms the input image pixelwise according to the equation O = 1/(1 + exp*(gain*(cutoff - I))) after scaling each pixel to the range 0 to 1.

Parameters:	image : ndarray Input image. cutoff : float Cutoff of the sigmoid function that shifts the characteristic curve in horizontal direction. Default value is 0.5. gain : float The constant multiplier in exponential’s power of sigmoid function. Default value is 10. inv : bool If True, returns the negative sigmoid correction. Defaults to False.
Returns:	out : ndarray Sigmoid corrected output image.

See also

adjust_gamma

References

[R84]

Gustav J. Braun, “Image Lightness Rescaling Using Sigmoidal Contrast Enhancement Functions”, http://www.cis.rit.edu/fairchild/PDFs/PAP07.pdf