在OpenCV中创建透明图像 [英] Creating transparent image in OpenCV

问题描述

我正在尝试在OpenCV中创建透明图像，并以jpg格式将其波动，但是没有成功.

I am trying to create a transparent image in OpenCV and wave it as jpg without any success.

我的代码是这样的:

string outputImageName="myimage.jpg";
Mat outputImage(outputRows,outputCols,CV_8UC4);
outputImage=cv::Scalar(255,255,255,255);
imwrite(outputImageName,outputImage);

但是图像不透明，颜色为白色.

But the image is not transparent and its colour is white.

我该怎么做?

如果OpenCV无法做到这一点，那么我有没有免费的库?

If OpenCV can not do this, is there any free library that I use for this?

推荐答案

似乎JPEG 不支持透明度 .不过，PNG确实可以，因此您将需要更改输出文件格式.

It appears that JPEG doesn't support transparency. PNG does, though, so you will want to change your output file format.

此外，alpha值255表示完全可见.将Alpha值更改为零，以使图像完全透明:

Also, an alpha value of 255 indicates full visibility. Change your alpha value to zero to make the image fully transparent:

outputImage=cv::Scalar(255,255,255,0);

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