[argyllcms] Re: Profile input white not mapping to output white
- From: Ben Goren <ben@xxxxxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Fri, 14 Dec 2012 09:44:17 -0700
On Dec 14, 2012, at 8:01 AM, Elle Stone <l.elle.stone@xxxxxxxxx> wrote:
> general purpose camera profile
This particular project has all been for a profile specific to the scene, with
the intention of re-shooting the target and re-profiling for each scene change.
And Graeme's latest test code is producing some great results.
*BUT*...I *am* going to (eventually) be moving on to creating a general-purpose
profile (or, perhaps, set of profiles for different typical lighting
conditions), and your post will absolutely be my starting point. Thanks much!
> Often target shots are underexposed, sometimes by two or three stops.
I've found that the raw data from a Canon 5DIII is pretty close to correct when
its built-in meter says you're one stop overexposed. Of course, all the common
processing tools have a stop of exposure boost built in, with compression for
the highlights. That's probably a pretty good idea overall, as there's no
headroom if you shoot to correctly expose the raw data. By underexposing by a
stop and pushing by a stop in post, you gain highlight headroom at the expense
of shadow noise, a tradeoff that is generally well worth making.
I've built a (rough draft of a) Canon Picture Style with a tone curve such that
the in-camera processing matches the actual raw data. Preliminary testing
suggests that the blinkies on the preview are a good match for actual
overexposure in the raw file. If so, I should be in good shape...all I have to
do is make the camera think it's overexposing by a stop and keep an eye on the
blinkies; when I do get the blinkies, I can know how much underexposure I have
to apply in camera to keep those highlights (if I want to keep them) and
therefore how much I'll have to boost exposure when developing. But this is all
preliminary....
So, thanks again. I'll report back when I've got something to report.
Cheers,
b&
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