Binarize adaptively

Binarize adaptively

Transforms any gray-level or color image to a binary image using one of the selected adaptive thresholding algorithms.

Inputs

image
Image to be thresholded. Color images will be converted to gray scale before applying the threshold.
windowSize
Size of the local window for adaptive threshold calculation.
absoluteLevel
Absolute threshold. The effect of this value depends on algorithm.
relativeLevel
Relative threshold. The effect of this value depends on algorithm.
algorithm
Adaptive thresholding algorithm.
invert
If true, inverts the result so that all foreground pixels become background and vice versa.

Outputs

image
Binary image

Thresholding algorithms.

Enumerator
RelativeToMean 

Local threshold is calculated by multiplying the mean gray level around a pixel by relativeLevel and adding absoluteThreshold to the result.

RelativeToMeanAndStd 

Local threshold is calculated by adding relativeThreshold times the standard deviation of the local gray levels to the mean gray level. absoluteLevel will be added to the result.

WeightedMeanAndVariance 

Local threshold t is calculated as \(t = \mu (1 + r (\sigma/\sigma_{\mathrm max} - 1)) + a\), where r stands for relativeThreshold, a for absoluteThreshold, and \(\sigma_{\mathrm max}\) for the maximum possible standard deviation, which is assumed to be 128. In document image binarization, a good value for relativeThreshold is 0.34, whereas absoluteThreshold is typically zero.