[HDR-photo] HDR as the new digital negative

[BillHughey]

Adobe's point about using DNG for archiving digital images is that we 
might not think to archive the manufacturers RAW reader along with the 
images.  I'm pretty sure that 20 years from now it could get real hairy 
trying to find a copy of that reader software...  It's a lot less likely 
that an open format will suffer the same problems.  My question was 
initially sparked by the other thread today on Chromatic Aberration and 
whether corrections should be applied to the raw files before combining 
into an hdr image.  This affects which you archive, RAW or HDR.

The question boils down to where is the cut point between science and 
art.  I have been using that metaphor here at work to describe the 
process of creating an hdr as opposed to creating a tone mapped image 
from the hdr.  If the process of creating the hdr image is ever to 
migrate into the camera (another thread perhaps, as I have done a bit of 
research into that side of things), we have to have a clear 
understanding of what can be done to the separate images before their 
combining into the hdr image.  That's what I am calling the science of 
the process. 

Making an HDR image generally involves interpolating the exposure values 
between the same pixel (alignment artifacts) in multiple images taken at 
different exposure values (ev's). There are various techniques for 
deemphasizing pixels that are either over exposed or are down in the 
noisy bottom of the camera curve.  Then there is the calculation of the 
camera curves (one for each color channel) for a specific camera sensor 
and the dead pixels and dark noise....   However, this all seems a lot 
more like science than tone mapping. 

Still the question from the other thread today is whether operations 
like Chromatic Aberration  reduction are associative over the process 
of  creating the HDR image from the RAW images.  Should it be applied 
before or after combining into HDR, does it matter?   I think the 
question was also whether it should be applied over the range of +/- ev 
settings?

As far as the PITA of laptop assisted AEB, expect to see smaller devices 
to appear in the next few years that can control as well as download 
from a camera.  So it will be more like two camera sized devices dongeled.

listmail at mab3d.com wrote:

> On Feb 8, 2007, at 12:29 PM, BillHughey wrote:
>
>> So, my plug for HDR is that it represents a handy digital negative  
>> format.  If anyone wants to get into the bits and bytes of RGBE,  
>> LogLuv32Tiff, DPX, or DNG  we can.  I am initially interested if  
>> anyone was thinking along the lines of using it for archival storage?
>
>
> I've been thinking along those lines for many years now. For my work  
> HDRs I actually archive the camera RAWs along with the "final" HDRs,  
> since the creation of HDRs is by no means an "exact science" just as  
> RAW processing has not yet been perfected. And, of course, I'm  
> learning new things about imaging technologies every day, so my  
> workflow changes and some vast improvements can be made to older  
> projects!
>
> As a general purpose "digital negative" for all my photography  
> (panoramic landscape, mostly), the huge stumbling block (for me) is  
> the PITA it is to actually *capture* an HDR image (bracketing,  
> composing the HDR in post, etc. - and I've been doing it for 5  
> years!). Even using CanonHDRcap or custom software to automate the  
> process, the requirement of a tethered laptop (and a tripod, since  
> I'm not that dextrous) takes the HDR out of any "fleeting moment"  
> shots. AEB is a nice "fallback" but many natural light scenes are  
> beyond such a limited range. Like you say, sometime in the (near)  
> future, we will be able to display more than our cameras can capture  
> in even 3 quick shots. The lack of in-camera support for serious HDR  
> capture and creation is why I deal with the 12-bit RAW format for my  
> archives and hope that Dave Coffin keeps up with his dcraw work.
>
> -Mark
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