[sane-devel] Making neutral scans

[m. allan noah]

On Fri, May 21, 2010 at 1:30 PM, Grant <emailgrant at gmail.com> wrote:
>>>> Not at all. I've seen two different units of the same scanner give
>>>> very different tone scans with the same options set. You need a
>>>> reference target to scan.
>>>>
>>>> allan
>>>
>>> But color management can be used after the fact, right?  I'd like to
>>> have a reference copy of everything I scan that I can apply things
>>> like color management or unsharp mask to later on.
>>
>> Yes- if the colors are reasonable, a profile specific to that machine
>> could be used to clean it further
>>
>> allan
>
> So if I make sure my gamma correction is always at 1.8 and I always
> leave all the sliders alone, I should be able to produce consistent
> reference scans that I can apply the same set of adjustments (ICC
> profile, maybe others) to later on to produce something as accurate as
> possible?
>
> I just want to make sure I'm not forgetting anything.

In theory, yes. But software upgrades might change a calibration algo,
and the sensors and lamp will drift over time, and the temperature in
the room will change, which might cause small changes. The only proper
way to get true stability is to run a color target periodically, and
rebuild your profile. That implies that you should be applying the
profile as you scan, or storing the scan of the color target serially
with your normal scans for later processing.

allan
-- 
"The truth is an offense, but not a sin"