OpenCV 4 with Python Blueprints - Second Edition

Using color manipulation via curve shifting

A curve filter is essentially a function, y = f (x), that maps an input pixel value, x, to an output pixel value, y. The curve is parameterized by a set of n + 1 anchor points, as follows:

Here, each anchor point is a pair of numbers that represent the input and output pixel values. For example, the pair (30, 90) means that an input pixel value of 30 is increased to an output value of 90. Values between anchor points are interpolated along a smooth curve (hence, the name curve filter).

Such a filter can be applied to any image channel, be it a single grayscale channel or the R (red), G (green), and ...