🚀 go-pugleaf

In article <3asv6s$m58@nrcnet0.nrc.ca> Mirek.Cygler@BRI.NRC.CA (Mirek Cygler) writes:
>	For some time we are experimenting with various ways of making color 
>slides using slidemakers. While the figures prepared on the Mac or PC pose
>no problems, the pictures prepared on SGI workstations with programs like
>Molscript or Raster3d do not come out right. Until now we have been creating
>these picture as rgb files, converting them to tiff format, transferring tiff 
>files to a Macintosh and used COMPOSER to display them and transfer to an AGFA 
>slidemaker attached to the Mac. We have found this process rather cumbersome
>and we are not happy with the final product. The colors on the slides come 
>quite different from what we see on the screen and the slides are always too
>dark. 

	The most common correction needed is a "gamma" correction.  You
pretty much have to determine the appropriate gamma correction for each
new output device, but it should remain a constant for that device.
Since you report that the slides are too dark, you will need a gamma
correction greater than 1.   Try gamma = 1.6, and if that is still too
dark try a larger value.  I do this sort of manipulation using the
ImageMagick package, for which the command would be something like

	mogrify -gamma 1.6 image.tiff

which would modify the image file in place so that all the colors are
lighter.

	Colors can also vary from device to device, but there is little 
that you can easily do about that.  It is possible, though tedious, to
do color warping on the red/green/blue components of the finished image,
but it's probably easier to pick a different set of colors to begin with.
Run off a color wheel or set of test patches on your output device and
just pick the ones which look nice for later use in making pictures.
If you are buying a new device, be it a slide maker or a color printer,
I'd make the color fidelity one of the selection criteria.

	For what it's worth the photoshop here uses a LaserGraphics
slide maker, but I don't know what it cost.  It's a fairly old machine.
They drive it on a Mac using Adobe Photoshop.
	
				hope that helps,

					Ethan A Merritt
					merritt@u.washington.edu