[R] Colour depth reduced to 12 by bitmap devices

[Prof Brian D Ripley]

On Thu, 29 Jun 2000, Prof Brian D Ripley wrote:

> On Thu, 29 Jun 2000, Clive Jenkins wrote:
> 
> > I am using R to create colour plots as bitmap files. I have created a
> > palette of 256 colours that I want to use, but the resultant output
> > files contain only 12 colours used in dither patterns. The result is the
> > same whether I use bmp() or png().
> 
> What about bitmap()?  Have you tried that? 
> 
> Internally bmp/png/jpeg use take a copy of the screen, so what you get
> depends on your graphics card driver. If you are seeing dithering in the
> PNG file, do you see it on screen?  Is your screen set to a truecolour
> mode?
> 
> bitmap() works via ghostscript.

I can confirm that none of png, bmp, bitmap dither on my system for this
example.


-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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