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Hi all,

It seems that OpenCV cannot write JPEG images with alpha channel. For example, the code

Mat readMat = imread("water.png", IMREAD_UNCHANGED);
imwrite(string("water.jpg"), readMat);

using water.png, a 4-channel image downloaded from here with white background, produces a jpg image with 3 channels and black background. Is this a bug in OpenCV, or expected behavior?

Thanks.

Hi all,

It seems that OpenCV cannot write JPEG images with alpha channel. For example, the code

Mat readMat = imread("water.png", IMREAD_UNCHANGED);
imwrite(string("water.jpg"), readMat);

using water.png, a 4-channel image downloaded from here with white background, produces a jpg image with 3 channels and black background. Is this a bug in OpenCV, or expected behavior?

Thanks.