Re: scanner profiling (again)
Re: scanner profiling (again)
- Subject: Re: scanner profiling (again)
- From: Jim Rich <email@hidden>
- Date: Tue, 16 Dec 2003 13:01:36 -0500
On 12/16/03 12:03 PM, "Armand Rosenberg" <email@hidden>
wrote:
>
OK, I understand. I am surprised, however, that using a target on the
>
same type of film as a properly exposed (and processed) positive
>
image leads to such large differences in wp and bp as I see. I also
>
don't understand why scene content would matter at all in the
>
situation I described.
Armand,
So one question to consider is why does each image I photograph have a
different white and black point?
As I pointed out in my last post factors like exposure, the scenes content,
and film processing cause the wp and bp to vary. It is just that simple.
It is the nature of light striking objects and then reflecting back on to
film or a sensor. It is not perfect. So a savvy operator then intervenes
to set the correct wp and bp for that situation.
As for when to adjust the wp and bp. I adjust wp and bp after I have used
one pair of profiles. That is to Assgin and then Convert to my WS.
I am not sure how else it can be a Photoshop ICC based workflow that uses
non ICC savvy scanner software. If you adjust the raw image before you
Assign the profile you are altering the raw state in which you created a
scanner profile. This makes the scanner profile invalid and is illogical in
an ICC workflow.
Here is a list of typical steps for this part of the scanning and image
processing part of the process.
1. Make a raw scan
2. Assign your custom scanner profile
3. Convert to your working space
4. Set wp, Set bp and adjust midtones: Use a tool like Curves or Levels.
Though you can use the new Highlight and shadow tool in CS
5. Adjust selective color areas; Use tools like Hue & Sat or Selective Color
6. Use Retouching and Masking options such as Selections or Snapshots
Of course you might want to use Adjustment layers for all of these image
processing adjustments.
If the scanner and software allows you to set up all of the image
processing parameters before the scan then you are ahead of the curve when
it comes to being paranoid about quantization errors that Photoshop image
processing might or might not introduce.
>
If those scanner driver settings actually modified the data capture
>
process, I would full-heartedly agree with you. But since those
>
settings appear to modify data after capture, I see no advantage to
>
having all those adjustments present in the scanner driver (except
>
for the *convenience* of not having to adjust each scan in PS later).
>
I agree if that is the case. So if your scanner does not work the way that
I have outlined, then you have to either deal with post image processing
or get a better scanner that allows you to make image processing
adjustments before the scan is created.
Jim Rich
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