[Gllug] Epson Stylus Photo 2100 && Linux?

[Mike Brodbelt]

On Sat, 2004-11-13 at 08:32 +0000, Tethys wrote:
> David writes:
> 
> >given your obvious knowledge of printing digital output under Linux, would you
> >say that the extra capabilities of modern top-of-line cameras, with their 8 
> >megapixel CCDs, can be used by the Gimp and the drivers that are available ?

The drivers can make use of the extra resolution. Whether 8 Megapixels
is a good idea on a 2/3" sensor is another matter entirely... I'm far
from convinced about that one. For example, comparing the measured
extinction resolutions on the Canon Powershot Pro1 (8 Megapixel, 2/3"
sensor) with the Canon 300D (6.3 Megapixel, APS sensor) shows that the
300D has the advantage in raw resolution. It also wipes the floor with
the 8 Megapixel model in the noise stakes. I tend to think that the 8
Megapixel compact cameras exist because the buying public mostly thinks
more pixels is automatically better, and never actually do any research
at all.

> I'm not sure which "extra capabilities" you're talking about, but you
> can now handle RAW images from high end digital cameras under GIMP with
> the RawPhoto plugin:
> 
> 	http://ptj.rozeta.com.pl/Soft/RawPhoto

Errkk. Yes. Sort of. Being a somewhat obsessive nerd when it comes to
digicams, I've played with dcraw and it's various front ends for quite a
while. I use RAW exclusively with my camera, so decent conversion is a
subject close to my heart :-). Now bear in mind that all my personal
experience with this is on Canon cameras - processing of different RAW
files may be different.

RAW conversion is not just a straight format conversion. For anyone who
isn't aware of what's involved with raw files, in a nutshell, a raw
converter needs to be able to read the raw sensor data from the file
(which dcraw does well), then do Bayer demosaicing, and finally apply a
gamma curve to map the linear sensor data into an appropriate colour
space for viewing/printing. Different raw converters do the demosaicing
differently. With Canon cameras, you can use the Canon DLL's, as used by
their software and some third party (Windows) software, Adobe's raw
converter (photoshop plugin, reverse engineered, partially based on
dcraw), or a couple of other  reverse engineered third party converters.
I've used 3 options under Linux, - dcraw, BreezeBrowser (uses Canon
DLL's, runs fine under Wine), and Bibble 4 (just released, closed source
but native Linux support). I've never been able to get results that look
(to me) as good from dcraw as from BreezeBrowser, though the RawPhoto
plugin has made it a lot easier. GIMP also lacks decent colour
management support, and looking at the dev list it appears that this
feature is one that didn't make it into 2.2, so it's still a lot harder
to get digital printing services working as well with GIMP on Linux as
they do with Photoshop on Windows or Mac. Gimp 2 can at least attach an
ICC profile as a display filter (and a Gamma curve), so if you can get
an ICC profile for your printer you should be able to use the printer
profile, and then find a gamma value that makes the images display on
screen the way they'll print.

I would *really* like to see decent colour management support and
properly integrated raw conversion in GIMP, including converting all the
metadata from RAW files into EXIF/IPTC/XMP. Dcraw currently ignores
metadata entirely, which means one needs a separate step to re-attach it
to a converted JPEG. I'd also like to see all the camera manufacturers
ditch their proprietary formats and move to Adobe DNG, which might put
some sanity back into things. The current situation is a mess on all
OS'es. Linux users have a slightly harder time of it than anyone else.

Mike.





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