piecewise image stretching using lookup tables

Good evening I need a little guidance on how to utilize LUT's (lookup tables) to create a function that can perform piece-wise stretching of an image.

Answer 1

[Walter Roberson]

One way is to use interp1, with either the default linear interpolation or the 'previous' method.

Another way instead of interp1 with previous is to use quantization. If you do not have the signal processing toolbox then you can quantize by using histcounts or the older histc