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Here in ongoing, the images normally are scaled down to a width of 300 pixels (linked to a full-size version). Currently, I’m using the open-source GD image library to do the photoreduction; the usability is excellent but I’m unsatisfied with the quality of the results. Herewith a survey of some approaches, because I’m sure lots of other people have this problem too. [Update: Holy Cow, did people respond. This is now photoreduction comparative research world headquarters.]
First of all, I freely confess that my understanding of graphics programming is very limited and; in this arena, I’m merely someone who wants to write some code to achieve a result.
Reduction by GD...
by Netpbm...
...and by Photoshop.
ImageMagick; thanks to Aaron Straup Cope and Ludovico Magnocavallo.
Corel PhotoPaint 8; thanks to Rob Bray.
IrfanView; thanks to Jim Ancona.
Jim also sent a version by Picture Window Pro.
The gimp; thanks to Stefan Eissing, Jeremy Zawodny, and Malcolm Tredinnick.
PaintShop Pro 7; thanks to Manuzhai.
Pything Imaging Library; thanks to Anthony J. Starks, Andrew Hallam, and especially Michal Bencur who published his own little photo-essay.