在MATLAB中使用.gif动画进行一些测试时,我意识到我无法读取gif的透明度.
例：
如果我做
[img,cmap]=imread('Finnandjake.gif');
img是4D,具有冗余的第三维(奇怪).挤压它(img = squeeze(img);),如果我显示它(imshow(img(：,：,30),cmap))：
透明度消失,使用图像中的另一种颜色作为背景,从而删除功能.然而
[img,cmap,alpha]=imread('Finnandjake.gif');
返回一个空的alpha.显然,Alpha的信息在图像的某处,我如何在MATLAB中读取它？
解决方法
/更新：我在
MATLAB file exchange提供了代码.已发布的版本与OCTAVE兼容,并附带一些文档.
我想出了这个解决方案.返回参数是堆叠图像,色彩映射和索引对应于透明度.
%do not use,instead use: http://www.mathworks.com/matlabcentral/fileexchange/55693-transparentgifread-filename-
function [stack,map,transparent]=transparentGifRead(filename)
if ~exist(filename,'file')
error('file %s does not exist',filename);
end
info=imfinfo(filename);
%Check if color map for all frames is the same
if any(any(any(diff(cat(3,info.ColorTable),[],3))))
error('inconsistent color map')
else
map=info(1).ColorTable;
end
%Check if transparent color for all frames is the same
if any(diff([info.TransparentColor]))
error('inconsistent transparency information')
else
transparent=info(1).TransparentColor-1;
end
import java.io.*
str = javax.imageio.ImageIO.createImageInputStream(java.io.File(filename));
t = javax.imageio.ImageIO.getImageReaders(str);
reader = t.next();
reader.setInput(str);
numframes = reader.getNumImages(true);
for imageix = 1:numframes
data = reader.read(imageix-1).getData();
height = data.getHeight();
width = data.getWidth();
data2 = reader.read(imageix-1).getData().getPixels(0,width,height,[]);
if imageix == 1
stack=zeros(height,1,numframes,'uint8');
end
%row major vs column major fix
stack(:,:,imageix) = reshape(data2,[width height]).';%'
end
str.close();
end
[stack,transparent]=transparentGifRead('tr.gif');
map(transparent+1,:)=[0,0] %offset 1 because uint8 starts at 0 but indices at 1
for frame=1:size(stack,ndims(stack))
imshow(stack(:,frame),map);
pause(1/25);
end
