* J M Cerqueira Esteves <jmce@artenumerica.com> [2002-01-04 15:07 +0000]:
* Jose' Sebrosa <sebrosa@artenumerica.com> [2002-01-04 13:29 +0000]:
Sometimes, truncation (floor) gives better aspect ratio than round. I would even not be surprised if, statistically, none of the methods were better.
Two examples:
1- Initial size: 51x49 Scale: 1/10 Final size (method=round): 5x5 Final size (method=floor): 5x4 Best method: round
2- Initial size: 54x56 Scale: 1/10 Final size (method=round): 5x6 Final size (method=floor): 5x5 Best method: floor
Those methods are not used by Photo and ImageMagick.
Correction: ImageMagick uses the "round" method as above in some cases, for instance when one uses convert --geometry 10%x10% original.png scaled.png or even convert --geometry 10% original.png scaled.png In this case it seems that both directions are treated separately and we find the problem above. In any case I have been talking of `convert' as it is run by Photo, with final max sizes instead of percent scales: convert --geometry 5x6 original.png scaled.png In this case `convert' tries to respect the aspect ratio, unless one follows the geometry argument with '!', in which case the image is distorted as needed. So, if some day Photo objects accepts a scale argument as in image.tag (..., scale=0.1, ..) or http://..../image?scale=0.1 it could be best NOT to call convert with the corresponding percentage argument but to precalculate new dimensions (W,H) in Photo.py and use convert -geometry WxH. Oh well, too many one-pixel thoughts for one day... :-)