Thanks you for your fast response. Would be cool if the new size has the same quality, but honestly I doubt it. If you didn't use completely uncompressed bmps or pngs before and now changed that there is no chance pictures can be reduced in size that much without quality loss.
But on way or another: I am interested to hear the result of your inspection.
Fix: Reinstall your complete GPU suite (AMD/Nvidia/Intel) which causes the driver to being repaired as well.