function res = grs2rgb(img,map,mingrayscale,maxgrayscale) %%Convert grayscale images to RGB using specified colormap. % IMG is the grayscale image. Must be specified as a name of the image % including the directory, or the matrix. % MAP is the M-by-3 matrix of colors. % % RES = GRS2RGB(IMG) produces the RGB image RES from the grayscale image IMG % using the colormap HOT with 64 colors. % % RES = GRS2RGB(IMG,MAP) produces the RGB image RES from the grayscale image % IMG using the colormap matrix MAP. MAP must contain 3 columns for Red, % Green, and Blue components. % % Example 1: % open 'image.tif'; % res = grs2rgb(image); % % Example 2: % cmap = colormap(summer); % res = grs2rgb('image.tif',cmap); % % See also COLORMAP, HOT % % Written by % Valeriy R. Korostyshevskiy, PhD % Georgetown University Medical Center % Washington, D.C. % December 2006 % % vrk@georgetown.edu % % Modified by % Silas J. Leavesley, PhD % University of South Alabama % Mobile, AL % 5-3-16 % % Changes made: % -Additional annotations added % -Input terms for min and max of image added - to allow scaling of % the image to a set min and max, instead of automatically scaling % the image to its own min and max % Check the arguments if nargin<1 error('grs2rgb:missingImage','Specify the name or the matrix of the image'); end; if ~exist('map','var') || isempty(map) map = hot(64); end; [l,w] = size(map); if w~=3 error('grs2rgb:wrongColormap','Colormap matrix must contain 3 columns'); end; if ischar(img) a = imread(img); elseif isnumeric(img) a = img; else error('grs2rgb:wrongImageFormat','Image format: must be name or matrix'); end; if maxgrayscale=maxgrayscale) = maxgrayscale; % Forces pixel values above the maximum grayscale value to be set equall to the maximum grayscale value a = a-mingrayscale; % Subtracts a minimum value (offset) from the image a(a<=0) = 1; % Needed to produce nonzero index of the colormap matrix (sets all pixels with value of <= 0 to a value of 1) ci = ceil(l*a/maxgrayscale); % Divides image by the max of the image (scales image from 0-1) then multiplies by the number of elements in the color look-up table (scales to go from 0 to the number of elements in the lookup table) % Colors in the new image [il,iw] = size(a); % Finds dimensions of input image r = zeros(il,iw); % Pre-allocates space for new r,g,b images g = zeros(il,iw); b = zeros(il,iw); r(:) = map(ci,1); % g(:) = map(ci,2); b(:) = map(ci,3); % New image res = zeros(il,iw,3); res(:,:,1) = r; res(:,:,2) = g; res(:,:,3) = b;