| Printer colors (Re: colorbar help) [message #9989] |
Wed, 01 October 1997 00:00 |
Stein Vidar Hagfors H
Messages: 32
Registered: May 1997
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Martin Schultz wrote:
[..snip..]
> Anyhow, I got another question concerning a related issue:
> I discovered that (at least with our color printer which is a QMS
> magicolor CX) a decrease in the RGB levels does not necessarily lead to
> darker colors but may actually yield brighter ones. Furthermore, it is
> quite hard to find RGB values that are not dithered on this printer
> (although I am using bits_per_pixel=8). So, I wonder whether this is a
> general problem of postscript or IDL or a specific problem of our
> printer.
>
> Thanks for any help,
> Martin.
It is a problem on many color printers - the trick is often
to use e.g., CMY (cyan, magenta, yellow) "coding" when inventing your
plot colors instead of RGB. The reason is that printing on paper
"subtracts"
light by adding ink - whereas the screen adds light by ... well, adding
light :-)
So, instead of units of Red (1,0,0), Green (0,1,0) and
Blue (0,0,1), try units of (I'm sure I'll get the names wrong
again, try them out yourself) Cyan/Magenta/Yellow, i.e.,
(0,1,1), (1,0,1), and (1,1,0). These are ofter very "clear and
bright" colors when printed. Mixing them *will* lead to dithering,
but mixing two of them will probably lead to less dithering than
mixing three of them.
Regards,
Stein Vidar
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