Hello all, I've been a linux user for some 5-6 years or so, and do my best
to use linux for everything.  However my hobby is photography and digital
imaging, which seems to be about to ring the death knell for my desktop
linux box due to performance problems.

The images I edit are usually around the 3500x2800 or so mark at 30 bits
depth.  I've recently tried Gimp on such images and have found it to be
lacking to put it mildly.

It wouldn't even load 30-bit TIFF files, I had to truncate them to 24-bit,
so losing three quarters of the range of each colour component, not much
of a problem until you start messing around with levels, contrast, and
other such things --- 1024 levels gives me much more headroom than 256!
Being as the scanner already loses masses of dynamics from a scanned
transparency, losing a further quarter is not something I want to do.

The second problem is speed.  The first thing I do when I scan a photo is
to mess with the levels, unfortunately with the preview button turned on,
as soon as I take my finger off the mouse button after dragging a marker
point I have to wait for many minutes while gimp redraws the image tile by
tile, taking 5 or so seconds for each tile.  During this redraw the
processor is at 100% on the gimp process, the disc is not thrashing, and
there is little or no CPU being spent on system processes so it's not a
problem with RAM.

Preview mode in other similar operations (e.g. gamma curve changes) is
similarly slow, while photoshop on the same hardware (PPro200 with 64 megs
of RAM) running under winblows is extremely quick, taking less than 5
seconds to do the whole preview.  Photoshop then cranks away at the image
for about 20 seconds or so once you've finished the preview, but not the
10 minutes or so that gimp takes.

I'm trying to find out what's going on here, am I doing something wrong,
or is there a fundamental performance problem with the levels tool and
other such tools? If there is, does anyone know of any alternative
programs that can preview contrast, gamma changes and levels changes on
large images in near-realtime?

Please don't unhelpfully suggest as someone else in a newsgroup did, that
I break out emacs and start to code, I'm no coder, I'm a photographer, and
not very good at that either ;-)

Thanks for your time.

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