"""
Contrast
--------
Functions for calculating the contrast of an image.
"""
[docs]def image_contrast(image):
"""
Calculates the 'Michelson' contrast.
Uses a method by Michelson (Michelson, A. (1927). Studies in Optics. U. of Chicago Press.), to calculate the contrast ratio of an image. Uses the formula:
(img_max - img_min)/(img_max + img_min)
Parameters:
image (ndarray): Image array
Returns:
float: Contrast value
"""
contrast = (image.max() - image.min()) / (image.max() + image.min())
return float(contrast)
[docs]def rms_contrast(image):
"""
Calculates the RMS contrast - basically the standard deviation of the image
Parameters:
image (ndarray): Image array
Returns:
float: Contrast value
"""
image /= image.max()
return float(image.std())