I frequently find the PubPeer excuse of compression artifacts in doctored images.
So lets have a look at that issue using the jpegoptim (manpage) and also jpeginfo (manpage). These are the usual effects
- Ringing – high contrast areas with waves
- Contouring, Banding, Pposterisation – extreme brightness changes
- Staircase noise – along curving edges
- Blockiness in “busy” regions – may mimick duplications
- Gibbs phenomenon – small highlighted area of large contrast
- Alias, Moiré, frequent color/brightness change
Now let’s have a look at the compression artifacts in descending quality (BTW this also good exercise for the upcoming 125kB Content Upload Filter, I am therefore adding filesize also)
