On 2007-12-24 13:01 +1000, Anthony Thyssen wrote: > Andre Majorel on wrote... > | On 2007-12-23 22:42 +1000, Anthony Thyssen wrote: > | > Andre Majorel on wrote... > | > | > | > | The document lends itself to quantisation very well ; it is > | > | typeset text with some orange highlighter so the scan contains > | > | only black, white and shades of fluorescent orange and grey. It > | > | could be adequately rendered with just, say, 8 colours : black, > | > | white, 3 greys and 3 shades of orange. > | > | > | > | Unfortunately, convert's native quantisation does not work that > | > | well with it. I end up with either too many shades of light grey > | > | for good compression or light brown instead of orange. > | > > | > I would specify the colors you want in a small image with just thouse > | > colors, than use -map. That is avoid the color quantization entirely. > | > | Thanks but that doesn't work too well. The original image is noisy > | and it's not obvious how to choose shades that are distant enough > | to avoid the dithering but not so distant that pixels end up > | remapped to the wrong hue. > | > | And the scaling problem is still there. > | > You can just turn off dithering using +dither. > In that case -map will just set colors to the closest color found in > the given color map image.
This *is* with +dither. It's not FS dithering, it's dithering resulting from noise in the output image. -- André Majorel <URL:http://www.teaser.fr/~amajorel/> Do not use this account for regular correspondence. See the URL above for contact information. _______________________________________________ Magick-users mailing list [email protected] http://studio.imagemagick.org/mailman/listinfo/magick-users
