/usr/share/psychtoolbox-3/PsychAlphaBlending/MaskImageOut.m is in psychtoolbox-3-common 3.0.9+svn2579.dfsg1-1.
This file is owned by root:root, with mode 0o644.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 | function mMasked=MaskImageOut(m [,alphaIn])
% Accept an image matrix "m" and return "nMasked", holding the same image
% but with adjusted alpha values. MaskImageOut sets full opacity
% for pixels with value zero and sets full transparency for pixels with
% non-zero value.
%
% If the optional alphaIn argument is specified then MaskImageIn sets
% zero pixels to alphaIn opacity instad of to full opacity, 255.
%
% see also: SetImageAlpha, MaskImageIn, AlphaDemo.
% HISTORY
%
% mm/dd/yy
%
% 1/28/05 awi Wrote it.
if nargin<2
alphaIn=255;
end
dims=size(m);
numDims=length(dims);
if numDims > 3
error('The matrix argument must have no more than three dimensions');
if numDims==2
mMasked=repmat(m, [1, 1, 3]);
else
mMasekd=m;
end
sumPlanes=m(:,:,1) + m(:,:,2) + m(:,:,3)
isZero=sumPlanes == 0;
nMasked(:,:,4)=isNonZero * alphaIn;
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