The image was produced by first scaling down the original picture in the GIMP and using ImageMagickconvert to cut it into 8 pixel wide slices, which were each compressed at different quality levels using Perl and cjpeg and recombined with ImageMagick montage. The exact commands used were:
The expression 2+78*(1-$n/29)**2.3 produces a nonlinear quality gradient from 80% down to 2% quality. The exponent was chosen by trial and error to yield a nice looking image with a good balance of high and low quality areas.
A picture of a flower (Phalaenopsis_(aka).jpg by André Karwath) compressed with successively lossier JPEG compression ratios from left to right. === Technical details === The image was produced