Why does convertFromImage copy image data?

Hey everyone, I am wondering about the decision to have cv::ocl::convertFromImage copy the image data into a new OpenCL buffer owned by a cv::UMat whereas cv::ocl::convertFromBuffer simply attaches the cl_mem buffer to a cv::UMat. Is there some reason that OpenCV cannot do the same for an OpenCL image2d? Unfortunately you can’t use convertFromBuffer on an image2d because it fails type and size assertions when attempted. Is this merely a case of not being needed yet, or is there some deeper issue that would render this impossible without a copy? Thanks.