From: John Stone (
Date: Sun Feb 18 2007 - 20:45:22 CST

  I read through the ImageMagick source code today to figure out
why their BMP loader fails to properly load the BMP files created
by Tachyon. It turns out that their loader is expecting the color
count field to be set to zero. If it is set to any other value than
zero, their reader treats it as a PseudoColor image, regardless if it was
encoded as BI_RGB (24-bit RGB). If I set the color count field to zero,
then the ImageMagick utilities read it without trouble. I'll have to do
more testing to make sure that setting the color count field to zero doesn't
cause new problems with other packages that were reading these files
without problems previously. If nothing problematic occurs with the various
windows utilities etc, then I'll change the code to emit a zero in the
color count field rather than 2^24.

On Sat, Feb 17, 2007 at 06:34:46PM +0100, Mario Valle wrote:
> On Windows GIMP refuses to load the BMP images created with Tachion
> rendering from VMD 1.8.5 .
> Also plain ImageMagick "convert" creates only grayscale images from them.
> The problem is that Tachion produces images of type PseudoClass
> $ identify plot.dat.bmp
> plot.dat.bmp BMP 504x478 PseudoClass 256c 706kb
> To have usable images you have to convert them this way:
> $ convert plot.dat.bmp -type TrueColor plot.dat.png
> Well, it is not a big problem, I want just share my workaround. But is
> it something simple to fix?
> Ciao!
> mario
> --
> Ing. Mario Valle
> Visualization Group |
> Swiss National Supercomputing Centre (CSCS) | Tel: +41 (91) 610.82.60
> v. Cantonale Galleria 2, 6928 Manno, Switzerland | Fax: +41 (91) 610.82.82

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