Re: Camera profiling with ICC et al
Re: Camera profiling with ICC et al
- Subject: Re: Camera profiling with ICC et al
- From: "edmund ronald" <email@hidden>
- Date: Fri, 12 Sep 2008 02:22:07 +0200
Hi Eric
Welcome to the party - even if you got here a bit late !
1. Happy to see the monster is now in production. Does it come wiith
the software to generate profiles and matrices ? How much does it cost
?
2-3-4 . Computing profiles on the fly from camera and illuminant
spd's is the way to go. Now let's get that info embedded in a standard
place in the files so that Raw converters who want to can use it !
5. Ulli's experiment is I believe similar to what prepress people
would set up for themselves. It's representative of something that is
meaningful for his readers. Your or I might differ, but then it is up
to us to educate the users on what metrics should be applied to
cameras.
Edmund
- Hide quoted text -
On Thu, Sep 11, 2008 at 5:07 PM, <email@hidden> wrote:
> Chris, Edmund, Uli, Eric, and others,
>
> Forgive me for coming into this thread late. I've been very remote and will
> be again till next week. A couple comments:
> 1) I have the new camSpecs monochromator from Image Engineering designed
> specifically for profiling by measuring camera spectral sensitivities out to the
> near IR. Compared to lab-grade monos, its fast, inexpensive, repeatably, and
> easy. I have no financial affiliation with IE except that I am a happy customer
> and helped design it. I have measured all my cameras, compared the results to
> lab-grade monos, and obtained very similar results. I've not seen near IR
> issues with any recent cameras.
> 2) Once the camera spectral sensitivities, linearity, training data, etc. are
> known then it is a simple and very accurate matter to determine the optimal
> profile for any given illumination.
> 3) However, an ICC profile can only handle one illumination condition at a
> time, though this does not preclude mixed (though not spatially varying in terms
> of SPD) illumination if it is adequately characterized. This is a limitation
> of ICC, though it is easily circumvented by building and embedding profiles
> on-the-fly based on the scene illumination metadata or precomputing and storing
> multiple profiles.
> 4) In my understanding, fundamentally, it is the latter approach that
> underpins and is an advantage of Adobe's method compared with a
> single-illumination-only ICC profile. Though Adobe doesn't use the ICC-wrapper, the Adobe profile
> data itself is fundamentally similar (and probably not incompatible with some
> massaging) to using multiple well-constructed ICC profiles. Adobe should be
> commended for their approach, not berated.
> 5) Assuming that rendering from scene-referred to output-referred is turned
> off (frequently not an easy assumption to check) it takes a very carefully
> designed, controlled, and executed experiment to objectively evaluate the profile,
> Adobe, ICC or otherwise. Much of what I have seen described here is simply
> inadequate for validating profile quality.
> Thanks,
> Eric Walowit
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