% TERNARYMIX Image blending and swiping over three images % % Function uses Barycentric coordinates over a triangle to interpolate/blend % three images. You can also switch to a swiping mode of display between the % three images. % % Usage: ternarymix(im, nodeLabel, normBlend, figNo) % % Arguments: im - 3-element cell array of images to blend. If omitted or % empty a file selection dialog box is presented. % nodeLabel - Optional cell array of strings for labeling the 3 nodes % of the interface. % normBlend - Sets the image normalisation that is used. % 0 - No normalisation applied other than image clamping. % 1 - Image is normalised so that max value in any % channel is 1. This is the default % 2 - Normalise to have fixed mean grey value. % (This is hard-wired at 0.2 . Edit function wbmcb % below to change) % 3 - Normalise so that max grey value is a fixed value % (This is hard-wired at 0.6 . Edit function wbmcb % below to change) % figNo - Optional figure number to use. % % This function sets up an interface consisting of a triangle with nodes % corresponding to the three input images. Positioning the cursor within the % triangle produces an interactive blend of the images formed from a weighted % sum of the images. The weights correspond to the barycentric coordinates of % the cursor within the triangle. The program starts out assigning a lightness % matched basis colour to each image. These colours are nominally red, green % and blue but have been constructed so that they are matched in lightness % values and also have secondary colours that are closely matched. % Unfortunately the normalisation of the blended image undoes some of this % lightness matching but I am not sure there is a good way around this. % % Hitting 'c' cycles the basis colours between the set of lightness matched % Isoluminant colours, the RGB primaries, and grey scale images. % % Hitting 's' toggles between blending and swiping mode. % % See also: LINIMIX, BILINIMIX, CLIQUEMIX, CYCLEMIX, BINARYMIX % Reference: % Peter Kovesi, Eun-Jung Holden and Jason Wong, 2014. % "Interactive Multi-Image Blending for Visualization and Interpretation", % Computers & Geosciences 72 (2014) 147-155. % http://doi.org/10.1016/j.cageo.2014.07.010 % % For information about the construction of the lighness matched basis % colours see: % http://peterkovesi.com/projects/colourmaps/ColourmapTheory/index.html#ternary % Copyright (c) 2012-2014 Peter Kovesi % Centre for Exploration Targeting % The University of Western Australia % peter.kovesi at 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. % % May 2012 - Original version % March 2014 - General cleanup and added option to specify colours associated % with each image when using the RGB option. % Dec 2014 - Updated isoluminant basis colours. Added interactive colour % mode section and swiping. function ternarymix(im, nodeLabel, normBlend, figNo) if ~exist('im', 'var'), im = []; end if ~exist('normBlend', 'var') || isempty(normBlend), normBlend = 1; end if ~exist('figNo', 'var') || isempty(figNo) fig = figure; else fig = figure(figNo); end [im, nImages, fname] = collectncheckimages(im); assert(nImages == 3, 'Three images must be supplied'); [rows,cols] = size(im{1}); if ~exist('nodeLabel', 'var') || isempty(nodeLabel) for n = 1:3 nodeLabel{n} = namenpath(fname{n}); end end % Set up three 'basis' images from the three input images and their % corresponding basis colours. colourdisplay = 'ISO'; imcol = {[0.90 0.17 0.00], [0.00 0.50 0.00], [0.10 0.33 1.00]}; for n = 1:3 % It is useful to truncate extreme image values that are at the ends % of the histogram. Here we remove the 0.25% extremes of the histogram. im{n} = histtruncate(im{n}, 0.25, 0.25); im{n} = normalise(im{n}); % Renormalise 0-1 basis{n} = applycolour(im{n}, imcol{n}); end % Display 1st image and get handle to Cdata in the figure % Suppress display warnings for images that are large S = warning('off'); figure(fig); clf, imposition = [0.35 0.0 0.65 1.0]; subplot('position', imposition); imshow(basis{1}); drawnow imHandle = get(gca,'Children'); warning(S) % Set up interface figure ah = subplot('position',[0.0 0.4 0.35 0.35]); % Draw triangle interface and label vertices theta = [0 2/3*pi 4/3*pi]+pi/2; v = [cos(theta) sin(theta)]; hold on; plot([v(1,:) 0], [v(2,:) 0], 'k.', 'markersize',40) plot([v(1,:) 0], [v(2,:) 0], '.', 'markersize',20, 'Color', [.8 .8 .8]) line([v(1,:) v(1,1)], [v(2,:) v(2,1)], 'LineWidth', 2) for n = 1:nImages text(v(1,n)*1.2, v(2, n)*1.2, nodeLabel{n}, ... 'HorizontalAlignment','center', 'FontWeight', 'bold', 'FontSize', 16); end coltxt = text(-1,-1,'ISO','FontWeight', 'bold', 'FontSize', 16); r = 1.1; axis ([-r r -r r]), axis off, axis equal % Set callback function and window title setwindowsize(fig, [rows cols], imposition); set(fig, 'WindowButtonDownFcn',@wbdcb); set(fig, 'KeyReleaseFcn', @keyreleasecb); set(fig, 'NumberTitle', 'off') set(fig, 'name', ' Ternary Mix') set(fig, 'Menubar','none'); % Set up custom pointer myPointer = [circularstruct(7) zeros(15,1); zeros(1, 16)]; myPointer(~myPointer) = NaN; fprintf('\nClick and move the mouse within the triangle interface.\n'); fprintf('Left-click to toggle blending on and off.\n'); fprintf('Hit ''c'' to cycle between isoluminant colours, RGB and grey.\n'); fprintf('Hit ''s'' to toggle between swiping and blending modes.\n\n'); blending = 0; hspot = 0; blendswipe = 'blend'; % Start in blending mode %-------------------------------------------------------------------- % Window button down callback function wbdcb(src,evnt) if strcmp(get(src,'SelectionType'),'normal') if ~blending % Turn blending on blending = 1; set(src,'Pointer','custom', 'PointerShapeCData', myPointer,... 'PointerShapeHotSpot',[9 9]) set(src,'WindowButtonMotionFcn',@wbmcb) if hspot % For paper illustration delete(hspot); end else % Turn blending off blending = 0; set(src,'Pointer','arrow') set(src,'WindowButtonMotionFcn','') % For paper illustration cp = get(ah,'CurrentPoint'); x = cp(1,1); y = cp(1,2); if gca == ah hspot = plot(x, y, '.', 'color', [0 0 0], 'Markersize', 40'); end end end end %-------------------------------------------------------------------- % Window button move call back function wbmcb(src,evnt) cp = get(ah,'CurrentPoint'); xy = [cp(1,1); cp(1,2)]; if strcmp(blendswipe, 'swipe') swipe(xy); else % Blend [w1,w2,w3] = barycentriccoords(xy, v(:,1), v(:,2), v(:,3)); blend = w1*basis{1} + w2*basis{2} + w3*basis{3}; % Various normalisation options if normBlend == 0 % No normalisation blend(blend>1) = 1; % but clamp values to 1 elseif normBlend == 1 || strcmpi(colourdisplay, 'GREY') % Normalise by max value in blend blend = blend/max(blend(:)); elseif normBlend == 2 % Normalise to have fixed mean grey value g = 0.299*blend(:,:,1) + 0.587*blend(:,:,2) + 0.114*blend(:,:,3); g(isnan(g(:))) = []; meang = mean(g(:)); blend = blend/meang*0.2; % Mean grey value of 0.2 blend(blend>1) = 1; % Clamp values to 1 elseif normBlend == 3 % Normalise so that max grey value is a fixed value g = 0.299*blend(:,:,1) + 0.587*blend(:,:,2) + 0.114*blend(:,:,3); blend = blend/max(g(:))*0.6; % Max grey of 0.6 blend(blend>1) = 1; % Clamp values to 1 end set(imHandle,'CData', blend); end end %----------------------------------------------------------------------- % Key Release callback % If 'c' is pressed the display cycles between using Lightness matched % colours, RGB and Grey. If 's' is pressed we toggle between swiping and % blending. function keyreleasecb(src,evnt) if evnt.Character == 'c' if strcmp(colourdisplay, 'ISO') colourdisplay = 'RGB'; set(coltxt, 'String', 'RGB'); imcol = {[1 0 0], [0 1 0], [0 0 1]}; for n = 1:3 basis{n} = applycolour(im{n}, imcol{n}); end elseif strcmp(colourdisplay, 'RGB') colourdisplay = 'GREY'; set(coltxt, 'String', 'Grey'); for n = 1:3 basis{n} = applycolour(im{n}, [1 1 1]); end elseif strcmp(colourdisplay, 'GREY') colourdisplay = 'ISO'; set(coltxt, 'String', 'ISO'); imcol = {[0.90 0.17 0.00], [0.00 0.50 0.00], [0.10 0.33 1.00]}; for n = 1:3 basis{n} = applycolour(im{n}, imcol{n}); end end elseif evnt.Character == 's' % Swipe/Blend toggle if strcmp(blendswipe, 'swipe') blendswipe = 'blend'; else blendswipe = 'swipe'; end end wbmcb(src,evnt); % update the display end %----------------------------------------------------------------------- % Generate swipe image given xy which has its origin at the centre of the % triangle with vertices at a radius of 1 function swipe(xy) % Convert cursor position to row and col coords x = round(( xy(1) + 1) * cols/2); y = round((-xy(2) + 1) * rows/2); % Clamp x and y to image limits x = max(1,x); x = min(cols,x); y = max(1,y); y = min(rows,y); % Three images. 1st image occupies top half, swiped vertically. 2nd and % 3rd images share bottom half and are swiped horizontally. swipeim = [ basis{1}(1:y, :, :) basis{2}(y+1:end, 1:x, :) basis{3}(y+1:end, x+1:end, :)]; set(imHandle,'CData', swipeim); end %------------------------------------------------------------------------ end % of main function and its nested functions %------------------------------------------------------------------------ % Given 3 vertices and a point convert the xy coordinates of the point to % Barycentric coordinates with respect to vertices v1, v2 and v3. % Assumes all arguements are 2-element column vectors. % Returns 3 barycentric coordinates / weights. function [l1,l2,l3] = barycentriccoords(p, v1, v2, v3) l = [v1-v3, v2-v3]\(p-v3); l1 = l(1); l2 = l(2); l3 = 1 - l1 - l2; % Simple clamping of resulting coords to range [0 1] l1 = min(max(l1,0),1); l2 = min(max(l2,0),1); l3 = min(max(l3,0),1); % Perhaps ideally if p is outside triangle p should be projected to the % closest point on the triangle before computing barycentric coords end %------------------------------------------------------------------------ % Function to set up window size nicely function setwindowsize(fig, imsze, imposition) screen = get(0,'ScreenSize'); scsze = [screen(4) screen(3)]; window = get(fig, 'Position'); % Set window height to match image height window(4) = imsze(1); % Set window width to match image width allowing for fractional width of % image specified in imposition window(3) = imsze(2)/imposition(3); % Check size of window relative to screen. If larger rescale the window % size to fit 80% of screen dimension. winsze = [window(4) window(3)]; ratio = max(winsze./scsze); if ratio > 1 winsze = winsze/ratio * 0.8; end window(3:4) = [winsze(2) winsze(1)]; set(fig, 'Position', window); end %---------------------------------------------------------------------------------- % Apply a colour to a scalar image function rgbim = applycolour(im, col) [rows,cols] = size(im); rgbim = zeros(rows,cols,3); for r = 1:rows for c = 1:cols rgbim(r,c,:) = im(r,c)*col(:); end end end