[argyllcms] Re: Number of patches - well behaved printer?

  • From: Rishi Sanyal <rishi.j.sanyal@xxxxxxxxx>
  • To: "argyllcms@xxxxxxxxxxxxx" <argyllcms@xxxxxxxxxxxxx>
  • Date: Thu, 24 Feb 2011 16:03:37 -0800

"I meant that, seeing as neg/print is a two-stage process, the result of 
whatever you are doing to get the image into a working space for retouching 
*should* take into account the nature of the paper that the neg would have been 
printed on."

I don't understand this either. The job of the input profile is to map your 
capture (scan or digital) to standard CIEXYZ or CIELAB values. You can then use 
this info to get your image into a standard device independent color space. Now 
your image file is ready for editing & subsequent output to any output device. 
Accuracy on the output end will now depend on an accurate profile that maps 
CIEXYz or CIELAB values to appropriate RGB values (or whatever space) for the 
output device. And of course at this point it's desirable to have an output 
device with a wide enough gamut to reasonably print most of the colors in your 
scanned + edited image.

Rishi

On Feb 24, 2011, at 7:57 AM, Idea Digital Imaging <qcore@xxxxxxxxxxxxxxxx> 
wrote:

> On 24 Feb 2011, at 13:53, Iliah Borg wrote:
> 
>> With input profiles for "moving target" media like film or digital captures 
>> (moving in the sense they depend on the colour of light, exposure, 
>> development, aging, etc) the task of the profiles is to convert colours, 
>> just colours - not the tone. Ironically, even auto-levels before applying a 
>> matrix-based profile do a better job than an elaborative hand-edited LUT 
>> profile with an embedded tone curve.
>> 
>> Alternatively, profiles done from targets shot using different exposures are 
>> in wide use; operator just selects the proper proper profile based on visual.
> 
> Hmm, I think that I need to see the results of this type of workflow? Neg 
> just "moved" far too much for me.
> 
> I spent a lot of time trying different approaches -- including working with 
> the complex developer curves that were available in Scanview's ColorQuartet 
> for one or two dot releases back then. No matter how successful the results 
> were for the test image we got mediocre results even when applying the same 
> corrections to a duplicate roll of neg processed at a different lab :(
> 
>>> And, as you also need to incorporate a wide choice of print papers into 
>>> colour managment, I didn't really see how profiling would be faster or 
>>> better than having a good scanner operator getting the colour right during 
>>> scanning?
>> 
>> I do not see how papers come into the blend. Applying output profiles is 
>> accomplished in a much later stage. Input profiles are helpers, they cut the 
>> time an operator spends working on an image; but most importantly they 
>> lessen the fatigue.
> 
> I meant that, seeing as neg/print is a two-stage process, the result of 
> whatever you are doing to get the image into a working space for retouching 
> *should* take into account the nature of the paper that the neg would have 
> been printed on.
> 
> -- 
> Martin Orpen
> T: 020 7739 5554 •  M: 07768 414558
> Idea Digital Imaging Ltd, 5 Christina Street, London EC2A 4PA
> Registered in England & Wales: 4051407  VAT Registration: 548100073

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