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annotate inst/colorgradient.m @ 886:a0c42a32c6c4

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Move conversion between each image type to imcast. * im2double.m, im2int16.m, im2single.m, im2uint16.m, im2uint8.m: move code into imcast. Fix several small bugs mainly dealing with indexed and logical images, small precision for Matlab compatibility, and increased performance. Expanded documentation. Added new tests. * imcast.m: implement the conversion between each image type instead of being a wrapper around functions for each conversion. This reduces code duplication, and places all very similar (but not equal) code together so that a bug fix in one can be easily notices that requires application in others. Expand documetation. Add more tests. * private/imconversion.m, private/im2float.m: remove no longer necessary function since this has all been moved to imcast. * COPYING: remove license for private/im2float.m and private/imconversion.m. * NEWS: make note of bug fixes for this functions.
author Carnë Draug <carandraug@octave.org>
date Mon, 24 Mar 2014 22:00:05 +0000
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children
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1 ## Author: Paul Kienzle <pkienzle@users.sf.net>
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2 ## This program is granted to the public domain.
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3
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4 ## -*- texinfo -*-
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5 ## @deftypefn {Function File} {@var{M} =} colorgradient (@var{C}, @var{w}, @var{n})
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6 ## Define a colour map which smoothly traverses the given colors.
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7 ## @var{C} contains the colours, one row per r,g,b value.
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8 ## @var{w}(i) is the relative length of the transition from colour i to colour i+1
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9 ## in the entire gradient. The default is ones(rows(C)-1,1).
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10 ## n is the length of the colour map. The default is rows(colormap).
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11 ##
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12 ## E.g.,
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13 ## @example
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14 ## colorgradient([0,0,1; 1,1,0; 1,0,0]) # blue -> yellow -> red
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15 ## x = linspace(0,1,200);
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16 ## imagesc(x(:,ones(30,1)))';
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17 ## @end example
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18 ## @end deftypefn
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19
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20 function ret = colorgradient (C, w, n)
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21 if nargin < 1 || nargin > 3
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22 print_usage;
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23 endif
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24
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25 if nargin == 1
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26 n = rows(colormap);
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27 w = ones(length(C)-1,1);
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28 elseif nargin == 2
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29 if (length(w) == 1)
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30 n = w;
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31 w = ones(rows(C)-1,1);
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32 else
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33 n = rows(colormap);
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34 endif
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35 endif
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36
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37 if (length(w)+1 != rows(C))
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38 error("must have one weight for each color interval");
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39 endif
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40
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41 w = 1+round((n-1)*cumsum([0;w(:)])/sum(w));
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42 map = zeros(n,3);
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43 for i=1:length(w)-1
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44 if (w(i) != w(i+1))
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45 map(w(i):w(i+1),1) = linspace(C(i,1),C(i+1,1),w(i+1)-w(i)+1)';
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46 map(w(i):w(i+1),2) = linspace(C(i,2),C(i+1,2),w(i+1)-w(i)+1)';
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47 map(w(i):w(i+1),3) = linspace(C(i,3),C(i+1,3),w(i+1)-w(i)+1)';
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48 endif
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49 endfor
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50
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51 if nargout == 0
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52 colormap(map);
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53 else
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54 ret = map;
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55 endif
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56 endfunction