add blue-white-red colormap

Author: dlegland

ImageM/+imagem/+actions/+view/SetImageColorMap.m

@@ -73,39 +73,42 @@ function run(obj, frame) %#ok<INUSD>
 
         % create the appropriate LUT array depending on LUT name and on
         % number of levels
-        if strcmp(name, 'inverted')
+        if strcmpi(name, 'inverted')
             lut = repmat(((nValues-1):-1:0)', 1, 3) / (nValues-1);
 
-        elseif strcmp(name, 'blue-gray-red')
+        elseif strcmpi(name, 'blue-gray-red')
             lut = gray(nValues);
             lut(1,:) = [0 0 1];
             lut(end,:) = [1 0 0];
 
-        elseif strcmp(name, 'colorcube')
+        elseif strcmpi(name, 'blue-white-red')
+            lut = imagem.util.color.blue2White2Red(nValues);
+            
+        elseif strcmpi(name, 'colorcube')
             map = colorcube(double(nValues) + 2);
             lut = [0 0 0; map(sum(map==0, 2)~=3 & sum(map==1, 2)~=3, :)];
 
-        elseif strcmp(name, 'red')
+        elseif strcmpi(name, 'red')
             lut = gray(nValues);
             lut(:, 2:3) = 0;
 
-        elseif strcmp(name, 'green')
+        elseif strcmpi(name, 'green')
             lut = gray(nValues);
             lut(:, [1 3]) = 0;
 
-        elseif strcmp(name, 'blue')
+        elseif strcmpi(name, 'blue')
             lut = gray(nValues);
             lut(:, 1:2) = 0;
 
-        elseif strcmp(name, 'yellow')
+        elseif strcmpi(name, 'yellow')
             lut = gray(nValues);
             lut(:, 3) = 0;
 
-        elseif strcmp(name, 'cyan')
+        elseif strcmpi(name, 'cyan')
             lut = gray(nValues);
             lut(:, 1) = 0;
 
-        elseif strcmp(name, 'magenta')
+        elseif strcmpi(name, 'magenta')
             lut = gray(nValues);
             lut(:, 2) = 0;
 

ImageM/+imagem/+gui/FrameMenuBuilder.m

@@ -200,6 +200,7 @@ function buildImageFrameMenu(obj, hf)
         addMenuItem(obj, lutMenu, SetImageColorMap('colorcube'),      'Color Cube');
         addMenuItem(obj, lutMenu, SetImageColorMap('prism'),          'Prism');
         addMenuItem(obj, lutMenu, SetImageColorMap('jet'),            'Jet');
+        addMenuItem(obj, lutMenu, SetImageColorMap('blue-white-red'), 'Blue-White-Red');
 
         matlabLutMenu = addMenu(obj, lutMenu, 'Matlab''s');
         addMenuItem(obj, matlabLutMenu, SetImageColorMap('hot'),      'Hot');

ImageM/+imagem/+util/+color/blue2White2Red.m

@@ -0,0 +1,65 @@
+function newmap = blue2White2Red(m)
+%BLUE2WHITE2RED   Blue to white to red color map.
+%
+%   blue2White2Red(M)
+%   Returns an M-by-3 matrix containing a blue to white to red colormap,
+%   with white corresponding to the CAXIS value closest to zero.  
+%   This colormap is most useful for images and surface plots with positive
+%   and negative values.
+%
+%   Example
+%     figure
+%     surf(peaks)
+%     colormap(bluewhitered)
+%     axis tight
+%
+%   See also HSV, HOT, COOL, BONE, COPPER, PINK, FLAG, 
+%   COLORMAP, RGBPLOT.
+
+% default number of values
+if nargin < 1
+   m = 256;
+end
+
+% define color "waypoints"
+bottom = [0 0 0.5];
+botmiddle = [0 0.5 1];
+middle = [1 1 1];
+topmiddle = [1 0 0];
+top = [0.5 0 0];
+
+% It has both negative and positive
+% Find ratio of negative to positive
+ratio   = .5;
+neglen  = round(m * ratio);
+poslen  = m - neglen;
+
+
+% Process colors for negative part
+new     = [bottom; botmiddle; middle];
+len     = length(new);
+oldsteps = linspace(0, 1, len);
+newsteps = linspace(0, 1, neglen);
+newmap1 = zeros(neglen, 3);
+
+for i = 1:3
+    % Interpolate over RGB spaces of colormap
+    newmap1(:,i) = min(max(interp1(oldsteps, new(:,i), newsteps), 0), 1)';
+end
+
+
+% Process colors for positive part
+new = [middle; topmiddle; top];
+len = length(new);
+oldsteps = linspace(0, 1, len);
+newsteps = linspace(0, 1, poslen);
+newmap = zeros(poslen, 3);
+
+for i = 1:3
+    % Interpolate over RGB spaces of colormap
+    newmap(:,i) = min(max(interp1(oldsteps, new(:,i), newsteps), 0), 1)';
+end
+
+
+% concatenate
+newmap = [newmap1; newmap];