jpeg artifact "removal", undoing the artifacts |
jpeg artifact "removal", undoing the artifacts |
Aug 21 2011, 09:46 PM
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Member Group: Members Posts: 890 Joined: 18-November 08 Member No.: 4489 |
first it is impossible undo the artifacts in jpeg images
now a lot can be done to synthetically "fix" them information IS LOST in the jpg compression yes it went into a black hole BUT the info was NOT conserved on the EH nor passed to a different dimension to be averaged out in the multiverse -- it's gone -- A test image " Kodak's lenna " --- a industry standard used to calibrate equipment in labs [attachment=25352:lenna.png] the eyes and nose are good for showing results ( "g" rated ones ) ( the below images are jpg's but , oh well . ) the orig. close up a jpg artifact added ( two saves at 65% 2x2x2x2 ) over the years i have found a few things to do this NOTHING works very very well . However GREYCstoration now Gmic works well , within reason. http://gmic.sourceforge.net/gimp.shtml a gimp add on and a bash command line tool . the gimp tool ONLY works on 8 bit / layer ( 24 bit rgb ) the command line tool works on 8,16 singed & unsinged ,and 32 bit floating point . warning this only artificially fixes them for now the gimp tool i like the "edge preservation flow" pde and the close up the artifacts are gone BUT the image is way too smooth add some noise a small amount 4 will do and the close up AND the orig. image the terminal command CODE gmic 4.2.04b.jpg -gimp_edgepreserving_smoothing 0.8,0.5,0.6,2.5,50,10,0,0 -gimp_noise 4,0,0,0,0 -o clean.png where "4.2.04b.jpg" is the input and "clean.png" is the output example from photojournal PIA14673.jpg left orig./ right "fix" |
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