Image Enhancement

ENHANCEMENT BY POINT PROCESSING

Histogram Techniques

• The histogram of an image is a plot of the numbers of occurrences of the various gray levels in the image against the gray level values.

• If we normalize the histogram by dividing the numbers of occurrences by the total number of pixels in the image, we get an estimate of the probability density function (PDF) of the (random) process generating the image gray levels.

• According to information theory, the entropy of the image, which is a measure of its statistical information content, is maximized when the PDF is uniform or flat.

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