[sm3600-devel] Re: brightness and level adjustment

[Marian E. <mar...@fr...>]

Glenn Ramsey wrote:
> 
> Hi Marian, *,
> 
> When I make a scan using the driver the intensity (not sure if
> that is the correct term.) levels are wrong.

This is really bad.

> The first thing I notice is that the final scan is always darker
> than the image in the xsane preview window.

The first question is, if this is true for other backends to. And - even
worse - it seems to be no issue for my setup.

Is it possible, that You have old backend-contrast and
backend-brightness settings other than zero (0)?

They can be found in the extended options. If they are set (and xsane
stores them permanently), the backend does additional scaling, that
cannot be predicted by the preview window.

I'll have to verify the issue, nevertheless.

> adjusting it later using GIMP.  The scanned image is too dark but
> after I use the levels tool to auto adjust the intensity levels it
> looks OK

Dark? Uh oh, with my setup I get very bright (bot not over-exposed)
scans, since we do the gain correction.

> The other thing I noticed is that the intensity values are always
> in the lower 80% (approx) of the range.

This would be not so critical, because You never should use the full
range of intensity. Ok, 80 percent is narrow, but uncorrected white is
never more than approx 60% or so.

> An ideas why this might be?

Please check the extended options and tell me, what You found. I'll
verify the issue with my scanner.

-- 

Mit freundlichen Gruessen / Yours sincerely

Marian Eichholz
Postmaster
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