Histogram quantization. Image histogram with every pixel frequency displayed (top left), every bin contains a unique intensity value. Percentile binned histogram (top right and bottom): every bin contains 1% of the intensity values. Potential local minima correspond to peak values in the histogram where the corresponding intensity/location in the image might be considered as a seed point. Histogram quantization minimizes the number of local minima in the image, thus reducing the chances of over-segmenting the image.