Andre Majorel on wrote...
| Hello all. I have large 600 DPI colour scans that I would like to
| convert to compact PNG. To let PNG do its work, the number of
| colours needs to be reduced.
|
| 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 like the quantiser to pick something along the lines of
| #000 #444 #888 #ccc #FFF for the greys and #FF9840 #804c20 #402610
| for the oranges.
|
| Some scaling would be required, as the thresholds for logical
| black and white are maybe #333 and #ddd in the original.
| Normalisation cannot be used because many pixels have at least one
| component set to 0xFF.
|
| How would you approach this ?
|
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.
Anthony Thyssen ( System Programmer ) <[EMAIL PROTECTED]>
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Anthony's Home is his Castle http://www.cit.gu.edu.au/~anthony/
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