function stretched_image = stretch( source_image );
% STRETCH full-scale contrast stretch a bitmapped image.
% OBSOLETE -- you probably want to use the built-in Matlab function IMAGESC() instead.
% assumes source_image is a array of pixels which can have values from -inf to +inf.
% creates image of same size with each pixel run through a linear transformation
% to scale it so pixels range in value from 0 to 255,
% with the darkest pixels at exactly 0.0 black, and the brightest pixels at
% exactly 255.
% (If you start with a uniformly distributed ("random") image
% with many, many more than 256 distinct values,
% then use round(stretch(image)) to convert to integers,
% the histogram will be somwhat flat --
% pixels from 1 .. 254 will have the same frequencies,
% but pixels 0 and 255 will only be half that many.
% by David Cary 1998-02-18


brightest = max(max(source_image));
darkest = min(min(source_image));
scale = 255/(brightest-darkest);

stretched_image = (source_image - darkest) .* scale;
% end stretch.m