[argyllcms] Re: relativ volume of gamut -- vrml comparison?
- From: "Preben Soeberg" <prsodk@xxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Mon, 7 Jan 2008 15:01:10 +0700
On Jan 7, 2008 12:13 AM, Gerhard Fuernkranz <nospam456@xxxxxx> wrote:
> Preben Soeberg wrote:
> > The actual profile, though tagged as an input profile, it is actually not
> > so. It is an abstract profile, used to convert the colors from the
> > demosaiced camera data, let's call these data's colorspace "Neutral". So,
> > in Canons DPP (Digital Photo Professional) program, you can choose between
> > different abstract profiles (Normal, Portrait, Landscape, Faithful,
> > Monochrome) or "Neutral".
> >
>
> By definition an "abstract profile" maps PCS to PCS. If the input to the
> profile is RGB (i.e. the demosaiced raw camera data), then the profile
> indeed an input profile and not an abstract one.
>
I see my mistake now. The input profile is actually just assigned to
the RGB data.
When using cctif, and the last profile has an uneven number, cctiff
always asks which Lab space you want to output in. When using cctif,
will it always assign first profile, convert to second, assign third
profile convert to fourth etc.?
Will it allways disregard embedded profiles?
> But w/o information what "Normal", "Portrait", "Landscape", "Faithful"
> and "Monochrome" are really supposed to do in detail, one can only
> guess. Is the colorimetry of these profiles possibly optimized for
> capturing different sets of spectra? Or are they rather different
> perceptual profiles, which implement different gamut mappings (possibly
> including gamut expansion to boost saturation)?
>
> I haven't seen the profiles yet. Which intent is recorded in the header?
> Are they matrix or LUT profiles? If LUT profiles, do they contain both,
> A2B1 and A2B0 tables, or just a single A2B table?
A correction to my previous information: The default profile is
"Normal" not "Neutral". All rhe profiles except Normal uses LUT
profile in the profile directory, all with 3 A2B tables.
There are some more profiles, but using the DOS command "DIR /OD /TA",
I can see which ones actually have been used.
There is also some very low gamut profiles, that has all 3 a2b and b2a
tables. Due to the naming, these ones seems to be region specific. I
have no idea what these ones is used for. Possibly for calculating
automatic RGB corrections (curves) in one part of the program (not for
raw processing).
I think the profiles has a primarily perceptual purpose (as their
names suggest),
They all give the higest gamut when combined with AdobeRGB, 7% - 8%
higher than for WideGamutRGB or for ProPhoto RGB.
Preben
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