Thanks, my source image is jpg format and i don't have control over it. The lanczos performs very badly on it so i guess there is no solution to my problem. Thanks again.
On 9/4/07, Anthony Thyssen <[EMAIL PROTECTED]> wrote: > > Fred Weinhaus on wrote... > | >Hi Fred, > | >Do you know how 2 / have a script to fix quality of a jpg image after > it's > | >being enlarged (e.g. resizing a 100x100 image to 400x400) ? > | >Thanks, > | >S. > | > | > | Hello S. > | > | Sorry, but I am not sure what problem you are having. When you have a > | jpg image, it has already lost some quality, which cannot generally > | be recovered. When you resize it, you lose some more quality > | depending upon which filter option you have used. If you resize it to > | another jpg, you lose even more quality depending upon the quality > | setting. The best you can do is start with a non-compressed image > | format, such as png. (It does not help at this point to convert from > | your jpg to png, you need an original uncompressed image). Then when > | you resize, use -filter lanczos (which I believe is the default), but > | make the output format png or some other non-compressed image format. > | > | That is the best that I can do to help. I know of no way to get back > | the losses from a jpg compressed image. > | > | > Fred is perfectly correct. > > I would add however that if the JPEG image is from a digital camera > you preserve and archive the exact original file from that camera. > And always process the image from that original image, if posible. > > If you need to save intermediate images, use PNG or the IM internal MIFF > format to prevent data loss. MIFF can save images at a even higher > 'bit quality'. > > MIFF format is however not compressed by default so if disk space is > important, save images to "image.miff.gz" IM will invoke the gzip > compressor automatically, and can read such a file too. > > PNG is my recomendation. You can also use Glenn Randers-Pehrson's > program "pngcrush" to compress PNG files optimially without data loss. > > A newer version is "optipng". > Anthony Thyssen ( System Programmer ) <[EMAIL PROTECTED]> > > ----------------------------------------------------------------------------- > Unix Security sat on the wall. > Unix Security had a great fall. > All the king's horses, > And all the king's men, > Couldn't get Security back together again. -- Unix > Haters > > ----------------------------------------------------------------------------- > Anthony's Home is his Castle http://www.cit.gu.edu.au/~anthony/ > _______________________________________________ > Magick-users mailing list > [email protected] > http://studio.imagemagick.org/mailman/listinfo/magick-users > _______________________________________________ Magick-users mailing list [email protected] http://studio.imagemagick.org/mailman/listinfo/magick-users
