[argyllcms] Re: Disable some patches SCANIN
- From: Ben Goren <ben@xxxxxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Tue, 28 Dec 2021 15:05:01 -0700
On Dec 28, 2021, at 7:19 AM, Carlos Lopez Sanahuja <carlospardines1@xxxxxxxxx>
wrote:
Hello, i'm creating an ICC profile for my camera. But glossy patches
are creating problems with it. Can i tell the scanin option to toggle
off some patches (ex: F1, G4 … )
Alas, if the glossy patches are problematic, so, too, are the matte ones;
they’re just not in-your-face problematic.
If you must create an ICC profile for a camera by photographing a reflective
target, the non-negotiable starting point is a perfect studio setup. The acid
test for a perfect studio setup is a pair of exposures. First is of a mirror;
the exposure should be pitch black save for the camera, with the lens centered
in the frame. Second is of a white piece of paper (etc.), which should be
evenly exposed edge-to-edge save for whatever peripheral illumination loss you
have from the lens.
But even this profile will be of limited utility. Basically, it’ll be good for
your studio light setup when shooting objects with reflective spectra close to
the samples on your target.
If you want to do better than the ICC profile supplied by your RAW developer,
you’ll need to determine your sensor’s spectral sensitivity. The way to do that
is to photograph a spectrum, such as one projected by a prism or diffraction
grating. Basically, you need to DIY a large spectroscope … and then there’s
some linear algebra involved, but nothing beyond what you get in a typical STEM
undergraduate course.
The good news is that the ICC profiles for many RAW developers are pretty good,
and quality control of major camera manufacturers is shockingly good. Unless
you have good reason to know that you need to make your own ICC profile, you
don’t.
b&
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