Re: fine art reproduction questions
Re: fine art reproduction questions
- Subject: Re: fine art reproduction questions
- From: neil snape <email@hidden>
- Date: Sun, 02 May 2010 09:34:53 +0200
- Thread-topic: fine art reproduction questions
on 1/05/10 23:22, Ben Goren wrote :
> On 2010 May 1, at 9:55 AM, neil snape wrote:
>
>> If you want to find out more about HDR , then go ahead there are lots of
>> sources,
>>
>> If you don't know a thing about the DR of a DSLR then you had better take a
>> look around.
>
> Neil, I think Roger and I are both fully aware of what HDR is and have a solid
> understanding of the dynamic range of modern DSLRs. Where we're getting
> confused is that the dynamic range of a DSRL far exceeds the dynamic range of
> an externally-lit non-fluorescent non-specular reflective object. HDR is great
> for, say, a scene of the deep shade at the bottom of Muir Woods with just a
> hint of sun striking a few treetops in the distant background...but that's
> quite a far cry from acrylic on canvas evenly lit with strobes -- even if said
> acrylic is a painting of that exact same forest scene.
What you are both missing then is the way your Dslr is going to respond to
the scene DR. No different than a scanner response BTW!
It's not about the source it's about how the raw files are processed and
about how a sensor has it's limits. Most processors these days have a TRC
(gamma if you want to call it that) with a curve that compresses the shadows
and highlights to approach what you think you see. If you set the TRC to
flat then you will have a closer representation of what the camera sees.
It's not perfect, it doesn't record a flat response.
If you want ot optimise ( this I said before) you can do so in many ways.
Obviously you can add a curve in Photoshop and do so in Luminosity mode.
That will falsify things a bit so integrity is lost.
You can use a multi layered export which is most likely easier than HDR, but
not necessarily better.
You asked how do you profile for this.
The easiest way I know of right now is the Color Checker chart, preferrably
Passport.
The software is Passport too which integrates with LR. OR DNG, or wait until
the plug ins come out for C1 etc.
That too is not perfect, no one will say it is.
Profiling for HDR is probably going to be harder, no idea if the profiles
can be built for that use. That is certainly not the intention of Passport.
What we do know is profiling for art work requires spectral source
profiling, preferably with a spectral matching. That HP did, with an adapted
system around it. From what I've heard but not seen Kodak made some multiple
colored captors for copy work , one can imagine a fairly complex matching
for that back too. Robin Myers would be up on those things, he seems to be
aware of everything concerning copy work.
All of the above are not out of the box systems.
You and I are using Dslr with at least one raw processor. Their function is
not flat copy work matching but pleasing scene rendering.
> Could you point us to some examples of art you've shot that required HDR for
> optimum results? Ideally, a side-by-side comparison of the baseline exposure
> and the final HDR composite?
I don't do copy work any longer. The last ones I did Dubuffet, Picasso, etc
might have benefited from the highlight bright colours, but were not like
Soulage paintings that definitely need expansion if you want to optimise the
dark information, that will get squashed in raw dev.
For examples and methods you will find lots of examples. I'm sure you'll
find the info you need to understand the power in HDR to make things work
when you need to optimise the image for output.
>
> Also, I wasn't quite clear on your workflow. You image the X-Rite Passport
> with multiple exposures, composite them (with what software? what settings to
> ensure consistency?), and then profile them with...what software? As far as
> I'm aware, the Passport only ships with software to make DNG profiles.
See above. And it's not my workflow but my suggestion for maximising your
potential workflow.
>
> And are you really satisfied with the Passport as a target for this kind of
> work? The ColorChecker by itself is obviously inadequate, but are those extra
> half-dozen near-spectral patches really enough for a significant improvement?
> And why the Passport instead of the SG?
Since you won't be doing any scene referenced spectral color matching with
what you or I have then yes it's the best thing as of late. I think others
are working on similar options, time will tell.
The pigments used in the Munsell/X-Rite charts are very flat response, and
work sit most light sources. This is only going to point you in the right
direction fast. If you want to make a Marty Fors correction you may get
closer but getting there is a long process.
Yet the pigments in the original are not flat response, reason why you may
have to optimise and maximise the potential of the copy.
>
> And, again, how are you printing these once you've imaged them? Surely your
> printer doesn't have more dynamic range than the original artwork...or does
> it? If so, what's your secret?
>
Ah there lays the problem. How you best adapt your source for today's
printers is how you got there in the first place. I have been and most
experts have been pushing keeping edited images in 16 bit Prophoto . Why?
Obviously there aren't any devices that have anywhere near that synthetic
potential, but with changes in the future there will be better things to
come. Even Adobe have a way of reducing clipping when moving to ( as you
said lesser devices) into smaller spaces that may or may not go into their
ACE.
I said if you want to maximise potential you can use options to expand the
range, I did not say that you are locked into any printer. If it were just
to shoot and present a okay image then you don't need HDR, nor a DNG
profile, or much of anything else.
No secret to maximising potential, it's a choice. The same can be said about
using a 50mm over 10, or a flat field lens over a general purpose. A MF is
going to be a lot better than Dslr, and a scan back can be again better. Yet
film can even in some cases look better.
Maybe this shows a few more reasons to consider other paths if you need them
. If you don't then don't bother.
Neil Snape
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