[sane-devel] canon 2710 slide ...

[James Knott]

Deiters wrote:
> I am pleased to see that someone is still interested in the
> FS2710S!
> 
> I have the overexposure problem, too. It is not always evident,
> however. I guess that 99% of my slides are scanned well, but
> clouds and a blue sky, or a bride in white dress are problematic,
> indeed.
> 
> The FS2710S does a self-calibration after power up, but that is
> not the cause of the problem.
> 
> I had a look at the SCSI traffic and found out that the Canon
> software transmits gamma tables before each scan. Unfortunately
> I was not able to intercept the contents of those gamma tables.
> There seem to be 4096 two-byte entries for each color channel,
> low byte first. But so far I have not been able to store a gamma
> curve myself. As also the contrast and brightness controls have
> no effect, I suspected that the FS2710 has no software control of
> its digitizer, and that all color corrections must be done by
> software (this is done by the recent backend).
> 
> However, the Canon (Windows-based) software does not have the
> "overexposure" problem,  and this proves that my assumption is
> not quite correct: The FS2710 does have some software control,
> but I do not know how to activate it. I would be grateful for
> good advice!

I've had a similar experience with my Epson Perfection 1260 Photo 
scanner.  A slide scanned in XP looks great.  Scanned in Linux, it's 
very dark.