"Ross Presser" on wrote...
| I've worked with converting grayscale images into 1bpp versions for
| two different classes of device: inkjet printing, which prefers a
| dithered image, and offset press plate printing, which prefers a
| halftoned image. Imagemagick is very good at producing dithered
| images, not so good at halftoning. For halftoning I was forced to
| bring in Ghostscript.
|
While Im can do halftoning. It does not do offset halftoning that is
needed for proper printing. At least not directly.
What is needed is a separate halftone threshold image for each channel
with a fourth one for 'black' when a CMYK is used. Currently that was
one aspect that was not provided for.
If you like to have a go at adding this, please do.
| The third way to go to 1bpp is quantization or thresholding, where you
| just take anything brighter than a certain point and make it white and
| anything darker is black.
|
dithering and hafltoning is actually a type of thresholding, with
different thresholds for each pixel value.
What I would like to add is a dithering technique that allows the used
of a specific color map. I have seen this used on very old PC's for
Icon generation, and would like to have it for the same purposes in IM.
Anthony Thyssen ( System Programmer ) <[EMAIL PROTECTED]>
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"Remember I'm a hologram, don't try these stunts at home."
-- Larry Niven & Steven Barnes, "The Barsoom Project"
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Anthony's Home is his Castle http://www.cit.gu.edu.au/~anthony/
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