make a colormap out of a screenshot

make_c_map_out_of_screenshot.m

function [cbar] = make_c_map_out_of_screenshot(impath,crop,column)
% ------ Help for make_c_map_out_of_screenshot -------
%
% Creates a colorbar from a screenshot of another colorbar.
%
% How to use:
% 1) Make screenshot of the colorbar (Ideally, have the left most column of
%    pixels right on the colormap)
% 2) Save as image file (png works, maybe other formats will not, try it out!)
% 3) Put path to file in some variable, e.g.:
%      >> impath = 'my_path_to_my_image' ;
% 4) (optional) If you need to crop the top and bottom, put the number of pixels
%    to crop in a variable `crop`, e.g.:
%      >> crop = [2 3] ; % will crops 2 pixels on top and 3 pixels on bottom
% 5) (optional) If you need to select a specific column from
%    the image other than the first one, specify it in a variable `column`, e.g.:
%      >> column = 4 ; % will take the 4th column for the colormap
% 6) Call the function:
%      >> cbar = make_c_map_out_of_screenshot(impath) ; % will put the colorbar in `cbar`
%      >> cbar = make_c_map_out_of_screenshot(impat,crop) ; % will also crop top and bottom
%      >> cbar = make_c_map_out_of_screenshot(impat,crop,column) ; % will also select the column you chose
%    If you want to test it (when chosing how to crop), use without output argument:
%      >> make_c_map_out_of_screenshot(impat,crop,column) ; % will not save the cbar but will plot a test figure
%
% ------ End Help for make_c_map_out_of_screenshot ----

% Copyright (c) 2018 Benoit Pasquier
%
% 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, including without limitation the rights
% to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
% copies of the Software, and to permit persons to whom the Software is
% furnished to do so, 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, EXPRESS OR
% IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
% FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
% AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
% LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
% OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
% SOFTWARE.

if nargin < 3
  column = 1 ;
end

if nargin < 2
  crop = [0 0] ;
end

foo = imread(impath) ;
foo_cut = foo(1+crop(1):end-crop(2),column,:) ;
cbar256 = squeeze(foo_cut) ;
cbar = double(cbar256) / 256 ;

if nargout == 0
  figure(666);
  contourf(peaks)
  colorbar
  colormap(cbar)
end