Schlagwort-Archive: upload

Isolated vertical or horizontal lines in gel images are not jpg compression artifacts

When preparing a lecture on image fraud in scientific papers, I frequently find the PubPeer excuse of compression artifacts. So lets have a look at that issue using jpegoptim (manpage) and also jpeginfo (manpage).

German Wikipedia explains 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 also filesize here)

original 893kB

Isolated vertical or horizontal lines in gel images are not jpg compression artifacts weiterlesen