Transparent background+setting alpha data
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Hi: I have matrix
x=[1 2 3; 0 2 3;0 0 3];
I want to create a png file where the 0s are transparent and the rest of values are half transparent...I tried the following:
x(x<=0)=NaN;
h=imagesc(x);
axis image
set(h,'alphadata',~isnan(x))
set(gca,'color','none');
set(gca, 'visible', 'off') ;
export_fig asda.png -transparent
(search expor_fig on this site you will find it,saveas acts weird sometimes so I prefer this one).
Problem is how do I make the rest of the ~isnan values half transparent?
if I use alpha(.5) the NaN will get back their colors (cancels the 'alphadata' command)
Thanks,
采纳的回答
x = [1 2 3; 0 2 3;0 0 3];
x = x / max(x(:)); % Scale to [0,1]
A = repmat(0.5, size(x));
A(x == 0) = 1; % 100% transparent
imwrite(x, 'asda.png', 'Alpha', A);
I do not find in the documentation, if 100% transparency is 1 or 0. So please test thiy.
更多回答（1 个）
Image Analyst
2012-9-30
0 个投票
Have you seen the official Mathworks documentation: http://www.mathworks.com/help/matlab/ref/imwrite.html#f25-742371
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