add double2rgb.m

Author: dlegland

src/@Image/double2rgb.m

@@ -0,0 +1,119 @@
+function rgb = double2rgb(obj, map, bounds, varargin)
+% Create a RGB image from values of an intensity image.
+%
+%   RGB = double2rgb(IMG, MAP, BOUNDS)
+%   Scales the values in IMG between in the interval specified by BOUNDS,
+%   then convert each value to the corresponding value of the color map
+%   given in MAP.
+%   If the image contains inf or NaN values, they are set to white.
+%
+%   RGB = double2rgb(IMG, MAP)
+%   Assumes extreme values are given by extreme values in image. Only
+%   finite values are used for computing bounds.
+%
+%   RGB = double2rgb(IMG, MAP, BOUNDS, BACKGROUND)
+%   Specifies the value of the background value for Nan and Inf values in
+%   IMG. BACKGROUND should be either a 1-by-3 row vector with values
+%   between 0 and 1, or one of the color shortcuts 'r', 'b', 'g', 'c', 'y',
+%   'm', 'k', 'w'.
+%
+%   Example
+%   % Distance map of a binary image
+%     img = Image.read('circles.png');
+%     dist = distanceMap(img);
+%     dist(img) = NaN;
+%     rgb = double2rgb(dist, 'parula', [], 'w');
+%     show(rgb);
+% 
+%   See also
+%     label2rgb, rgb2hsv
+%
+
+% ------
+% Author: David Legland
+% e-mail: david.legland@inrae.fr
+% Created: 2020-01-14,    using Matlab 7.9.0.529 (R2009b)
+% Copyright 2010 INRA - Cepia Software Platform.
+
+% HISTORY
+
+if nargin < 2 || isempty(map)
+    map = 'parula';
+end
+
+% ensure map is a numeric array
+if ischar(map)
+    map = feval(map, 256); %#ok<FVAL>
+end
+
+% extract background value
+bgColor = [1 1 1];
+if ~isempty(varargin)
+    bgColor = parseColor(varargin{1});
+end
+
+% get valid pixels (finite value)
+valid = isfinite(obj.Data);
+if ~exist('bounds', 'var') || isempty(bounds)
+    bounds = [min(obj.Data(valid)) max(obj.Data(valid))];
+end
+
+% convert finite values to indices between 1 and map length
+n = size(map, 1);
+inds = (obj.Data(valid) - bounds(1)) / (bounds(end) - bounds(1)) * (n-1);
+inds = floor(min(max(inds, 0), n-1))+1;
+
+% compute the 3 bands
+dim = size(obj);
+r = ones(dim) * bgColor(1); r(valid) = map(inds, 1);
+g = ones(dim) * bgColor(2); g(valid) = map(inds, 2);
+b = ones(dim) * bgColor(3); b(valid) = map(inds, 3);
+
+% concatenate the 3 bands to form an rgb image
+if length(dim) == 2
+    % case of 2D image
+    rgb = cat(3, r, g, b);
+    
+else
+    % case of 3D image: need to play with channels
+    dim2 = [dim(1:2) 3 dim(3:end)];
+    rgb = zeros(dim2, class(map));
+    rgb(:,:,1,:) = r;
+    rgb(:,:,2,:) = g;
+    rgb(:,:,3,:) = b;
+end
+
+newName = '';
+if ~isempty(obj.Name)
+    newName = sprintf('label2rgb(%s)', obj.Name);
+end
+
+% create Image object from data
+rgb = Image(permute(rgb, [2 1 3 4:length(dim)]), 'Type', 'color', ...
+    'Parent', obj, ...
+    'Name', newName);
+
+function color = parseColor(color)
+
+if ischar(color)
+    switch(color)
+        case 'k'
+            color = [0 0 0];
+        case 'w'
+            color = [1 1 1];
+        case 'r'
+            color = [1 0 0];
+        case 'g'
+            color = [0 1 0];
+        case 'b'
+            color = [0 0 1];
+        case 'c'
+            color = [0 1 1];
+        case 'm'
+            color = [1 0 1];
+        case 'y'
+            color = [1 1 0];
+        otherwise 
+            error('Unknown color string');
+    end
+end