Implements a simple grayworld white balance algorithm

dst = cv.autowbGrayworld(src)
dst = cv.autowbGrayworld(src, 'OptionName',optionValue, ...)

Input

• src Input array. Currently only works on color images of type uint8 (3-channels).

Output

• dst Output array of the same size and type as src.

Options

• Thresh Maximum saturation for a pixel to be included in the gray-world assumption. default 0.5

The function cv.autowbGrayworld scales the values of pixels based on a gray-world assumption which states that the average of all channels should result in a gray image.

This function adds a modification which thresholds pixels based on their saturation value and only uses pixels below the provided threshold in finding average pixel values.

Saturation is calculated using the following for a 3-channel RGB image per pixel I and is in the range [0,1]:

 Saturation[I] = (max(R,G,B) - min(R,G,B)) / max(R,G,B)

A threshold of 1 means that all pixels are used to white-balance, while a threshold of 0 means no pixels are used. Lower thresholds are useful in white-balancing saturated images.