I use sample() in C++ code to make 'resize' instead of scale(), and the result is much better, so I think it's the algorithm of 'resize' that effects the result.
As you have mentioned, I tried different dither but it didn''t work. 2009/10/28 Anthony Thyssen <[email protected]> > On Tue, 27 Oct 2009 19:44:42 +0800 > ZHOU Xiao-bo <[email protected]> wrote: > > | hi: > | > | I found that when I resize and quantize a gif such as > | > | "http://img1.cache.netease.com/img09/logo/logo.gif"; > | > | using "convert logo.gif -resize 160x46 -colors 16 out.gif", I got a > | gif with bad quality. > | > | But if I use "convert logo.gif -resize 160x46 tmp,gif"; and then > | "convert tmp.gif -colors 16 out.gif", the quality is much better. > | > | I think it's because the platte has been changed when resizing. > | I found that platte of 'tmp.gif' is much larger than that of > | logo.gif. > | So, how can I get the better output image in c++ code? > | thanks a lot. > | ZHOU Xiaobo > | > Resize does not change the palette, it destroys the palette as it generate > completely new colors as part of the process. > > The save to gif however restricted the colors to a new 256 color palette > as part of the save. This may be the cause of the improved result > > You could try the equivalent of > convert logo.gif -resize 160x46 -colors 256 -colors 16 out.gif > > Also you may like to try using a different dither, > -dither FloydSteinberg > which may produce a better result for small images. > > > Anthony Thyssen ( System Programmer ) <[email protected]> > > ----------------------------------------------------------------------------- > `` Well you know what they say... All Good Things... '' > StarTrek, New Generations (Final Epsoide) > > ----------------------------------------------------------------------------- > Anthony's Home is his Castle > http://www.cit.gu.edu.au/~anthony/<http://www.cit.gu.edu.au/%7Eanthony/> > _______________________________________________ > 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
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