% ADJGAMMA - Adjusts image gamma.
%
% function g = adjgamma(im, g)
%
% Arguments:
%            im     - image to be processed.
%            g      - image gamma value.
%                     Values in the range 0-1 enhance contrast of bright
%                     regions, values > 1 enhance contrast in dark
%                     regions. 

% Copyright (c) 2001 Peter Kovesi
% School of Computer Science & Software Engineering
% The University of Western Australia
% http://www.csse.uwa.edu.au/
% 
% Permission is hereby granted, free of charge, to any person obtaining a copy
% of this software and associated documentation files (the "Software"), to deal
% in the Software without restriction, subject to the following conditions:
% 
% The above copyright notice and this permission notice shall be included in 
% all copies or substantial portions of the Software.
%
% The Software is provided "as is", without warranty of any kind.

% July 2001

function newim = adjgamma(im, g)

    if g <= 0
	error('Gamma value must be > 0');
    end

    if isa(im,'uint8');
	newim = double(im);
    else 
	newim = im;
    end
    	
    % rescale range 0-1
    newim = newim-min(min(newim));
    newim = newim./max(max(newim));
    
    newim =  newim.^(1/g);   % Apply gamma function