with r2875, "-s" option given at opj_compress like this : opj_compress -i bike.ppm -o bike.ppm_s21.j2k -s 2,1

... produce a J2K image with the same size as the original but with a SIZ marker multiplied by 2 in the x-direction. It does not actually subsample, it multiplies the size signaled in the SIZ marker.

I've been playing with subsampling in openjpeg lately and have had trouble determining if the issue is with the encoder (openjpeg) or the decoder (Safari). Whenever I use the openjpeg -s option, all images become distorted in Safari (or any Apple viewer), the images' dimensions are doubled in one or both dimensions when using anything but "1,1". The images display at the correct dimensions on Ubuntu.

I also notice that the file sizes are identical.

This issue is important to me, if there's anything I can do to help, let me know.