In support of the right to marry the one you love, today the equals sign swept facebook, and a teachable moment about lossy image compression has come in its wake.   The first The image started as a perfect set of squares.  Here’s what the SFR of a perfect edge looks like: I don’t have the original image, I had to recreate this in GIMP.   From the very first person that uploaded this, the image began to degrade. Each time the image was re-saved, re-uploaded and re-processed and re-compressed, the image quality gets worse.  Sharpenning makes the MTF score go up some but does not recover the crisp edge of the original.  Watch for the drop in MTF50 which correlates well with perceived image quality.