rgb2rgbe.m
91b521f14899Bashardoust_SystCoord

rgb2rgbe.m
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			function rgbe = rgb2rgbe(rgb)
			%rgb2rgbe Convert RGB HDR pixels to 8-bit RGBE components.
			% RGBE = RGB2RGBE(RGB) converts an arry of floating-point, high dynamic
			% range (R,G,B) values to an encoded UINT8 array of (R,G,B,E) values.
			%
			% Reference: Ward, "Real Pixels" (pp. 80-83) in Arvo "Graphics Gems II," 1991.

			% Copyright 2007-2013 The MathWorks, Inc.

			% Reshape the m-by-n-by-3 RGB array into a m*n-by-3 array and find the
			% maximum value of each RGB triple.
			rgb = reshape(rgb, numel(rgb)/3, 3);

			maxRGB = max(rgb,[],2);
			[f,e] = log2(maxRGB);
			tmp = f*256./maxRGB; % Reusing maxRGB causes NaN values.
			rgbm = bsxfun(@times,rgb,tmp);
			rgbe = uint8([rgbm, e+128]);

			% Pixels where max(rgb) < 1e-38 must become (0,0,0,0).
			mask = find(maxRGB < 1e-38);
			rgbe(mask, :) = repmat([0 0 0 0], [numel(mask), 1]);