[sane-devel] Making neutral scans

[m. allan noah]

On Fri, May 21, 2010 at 1:53 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.
>
> Storing the scan of the color target as I scan is an interesting idea.
>  Could the same thing be done with a "white marks" target to later
> move pixels to eliminate artifacts?

Yes- though checking the manual for a calibration procedure would be easier :)

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