[l2h] pstoimg on cygwin?

[Alle Meije Wink]

Hi-

I have installed latex2html on cygwin -after installing netpbm and perl 
(which was on there from the beginning) and following the instructions 
at [http://www.cs.utexas.edu/~suvrit/work/l2h.html]. Everything worked 
in one go, no complaints.

Then I tried pstoimg on a black-and-white .eps file, got a png file 
exactly as expected.

Then pstoimg on a color .eps file (made with gnuplot), and I got this error:
> $ pstoimg IAN_PER3rawrotation.eps 
> pstoimg V2002-2-1 (Revision 1.16, Perl 5.008007)
> pstoimg: Processing IAN_PER3rawrotation.eps
> pstoimg: Error: "/usr/bin/ppmquant 256 < /tmp/p612.pnm | /usr/bin/pnmtopng  > IAN_PER3rawrotation.png" failed: 

It doesn't say why, but when I run the command between quotes I get:
> $ /usr/bin/ppmquant 256 < /tmp/p612.pnm | /usr/bin/pnmtopng  > IAN_PER3rawrotation.png
> pnmcolormap: making histogram...
> pnmcolormap: Scanning image 0
> pnmcolormap: 7 colors so far
> pnmcolormap: Scanning image 1
> pnmcolormap: Image 1 depth (1) is not the same as Image 0 (3)
> pnmcolormap failed, rc=256
> pnmtopng: Error reading magic number from Netpbm image stream.  Most often, this means your input file is empty.

All I know at this point is that ppmquant, or rather, a call inside 
ppmquant to pnmcolormap, goes wrong in cygwin.
Does anyone else know of this problem, and has anyone found a workaround 
yet?

If it helps, the gnuplot file that I use has these output options:
> set size 2.2,1.1
> set terminal postscript eps enhanced color "Helvetica" 28
> set output "IAN_PER3rawrotation.eps"
> set border 15 lw 2
> set key bottom left
[clip]

Maybe one of these options (`enhanced') screws up pstoimg?

Just to make sure:
Running the same commands in Linux results in a beautiful PNG file! 
Also, the EPS and PNM files in cygwin look completely fine. See
http://www.wbic.cam.ac.uk/~amw71/IAN_PER3rawrotation.eps
http://www.wbic.cam.ac.uk/~amw71/p612.pnm

Many thanks for all your suggestions.

Best wishes
Alle Meije Wink