A point operation maps each pixel intensity to a new intensity using a fixed function. Brightness adds an offset; contrast scales the distance from mid-gray: out = (in - 128) * c + 128 + b. A contrast gain below 1 compresses the histogram toward mid-gray, above 1 spreads it out.
Remapping intensities to improve contrastHistogram equalization builds the cumulative distribution of intensities and maps each level to (cdf(v) / N) * 255. Levels with many pixels are pushed apart while sparse levels are merged, which flattens the histogram and spreads detail across the full 0-255 range.
Read the histogram
A low-contrast image has a narrow, tall histogram clumped near one value. Equalization should widen it. If you over-stretch brightness first, equalization has little left to do.