The url "qrc://" probably has no meaning in OpenCV. QImage knows how to translate this url and understands that it means, "look in the compiled resources for this file and load the image from it".

The solution? Two possibilities: (1) Don't build the file into compiled resources, make it a disk file. (2) Use QImage to read it from compiled resources, then convert the bits into something that OpenCV can understand. I am sure there is a way to do that.