[argyllcms] Re: Calculate RAW importer profiles ?

  • From: Anders Torger <torger@xxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Fri, 31 Jul 2015 22:25:30 +0200

On camera color.

Very little sits in the raw format itself, almost nothing actually, The
color conversion takes place in the raw converter (and mirrored
functionality in the in-camera JPEG conversion). Some matrix, a curve
and a lookup table, and highlight rolloff handling, black level
handling, possibly some spatially varying aspects too, and almost
certainly white-balance-dependent variations.

That is publishing their color handling would not be to publish some
documentation on a raw format, but to publish the actual software that
renders the colors. And what would we do with that? We could then
implement our own raw converter that copies the raw converstion
pipeline from there, but there wouldn't be a natural way to incorporate
the look into say Lightroom or other big well-known software.

I don't know how Nikon does it, but a little bit of how Hasselblad
does, they have an own internal custom profile format layered for
several different lights, blended between depending on white balance
setting, similar do dual-illuminant DCPs, but Hassy has up to four
illuminants. So to get Hasselblad's color into some other software it
would need to have Hassy's color pipeline as well.

There's not been much standardization work around camera profiling, and
there are many different ways to handle camera color. Different raw
converters does it in different ways, and different cameras does it in
different ways.

We can surely mimick color by sampling and creating a new set of
profiles that suits the rendering pipeline of our preferred software,
but to get exactly the same behavior we need exactly the same pipeline.

Should also be said as well that there's no law of nature that the
camera manufacturer's color is best. They don't really have any key
information that we can't get from profiling. I can't deny though that
they generally do a very good job, and for example Adobe often doesn't.

In any case if I would spend time on camera profiling I would choose to
spend time on trying to get good at making camera profiles rather than
trying to mimick the look of the manufacturer. If I really would want
the look of the manufacturer, I'd use the manufacturer's software, you
can always export to TIF if you like to post-process further in some
other software.


On 07/27/2015 10:25:07 PM, Adriaan van Os wrote:

"Problems" yes... except that it's a problem intentionally created
the camera vendor, by keeping their color handling secret.

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