[HDR-photo] HDR as the new digital negative

[Ferrell McCollough]

Bill, I'm thinking along the same lines as HDR as a digital negative so I 
took some time to really test the idea. In theory .hdr as a digital negative 
makes sense. However, I find that there are differences within an .hdr file 
depending on what program does the merging. Using the same source images, I 
created an .hdr file from Photoshop, FDRtools, Photomatix, and Artizen.

The algorithm for merging is different for each program. Particulary how 
they choose the luminosity of a final pixel based on a stack of three pixels 
(three source images). Let's say you have an almost black pixel, almost 
white pixel (nearly blown) and a gray pixel. One program may ignore the 
white and black and choose the gray pixel, the other may choose the bright 
white pixel and another may throw out the white one and average the gray and 
black. They have different working thresholds.

Oddly enough some programs don't open their competitors .hdr file. For 
example, Artizen won't open FDRtools .hdr files. Also some .hdr files tone 
map better if they were created by another companies merging program. For 
example, when Photomatix.hdr is opened in Artizen it looks better than with 
Artizen's own .hdr. However in most cases, I've found that the best results 
are when the program tone maps an .hdr file that it created.

There are also lots of things that go on between the raw file and the .hdr 
file that are program specific. There are several different approaches to 
Ghost removal which not only vary in today's results but will certainly 
improve in years to come. It would be nice to have the RAW source files to 
merge with a better ghost removal algo in 2017, even 2007 for that matter.

So back when we'd say in the film days, "it's in the can" I think we can say 
with HDR "all the light is in the can"  but it varies depending on who did 
the merging.

Ferrell



----- Original Message ----- 
From: "BillHughey" <billhughey at eacceleration.com>
To: "High Dynamic Range Photography" <hdr-photo at hdr-photography.com>
Sent: Thursday, February 08, 2007 12:29 PM
Subject: [HDR-photo] HDR as the new digital negative


>I had thought to discuss the technical merits of HDR as a negative format 
>over the established (?) DNG format or perhaps the motion picture industry 
>standard DPX.  However that discussion gets bogged down in things like how 
>many bits do you need to store a photo of angels dancing on the head of a 
>pin!  Dry...
>
> Lets say you have been doing some HDR photography today, 2007.  If you 
> read the article referenced below, you might wonder what your photos will 
> look like in the year 2017 when you are showing them to your grand kids. 
> If you saved then as jpegs or tiffs at todays screen ranges of 300:1 
> (8bits per color channel) as most of our photos are stored today, they 
> might look a little flat next to images taken with the cameras of 2017 and 
> displayed on screens that have a range of 10,000 : 1 or better.
>
> Okay, so you have your HDR 'negatives' still around somewhere in your file 
> system.  After finding them, you use the tone mapping programs of the day 
> (2017 remember).  Tone mappers have improved greatly and the key idea is 
> that now they don't have to work as hard because they are not scaling down 
> to a 300:1 display anymore!  So the images that you show your grand kids 
> will look even better than when you took them back in 2007.
>
> While this may not be tops on the list of the average amateur 
> photographer, think of the investment that pro photographers have in their 
> art!  Preserving that investment against the future should be on their 
> minds today.
>
> 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?
>
> Oh, and notice the fantastic color photograph taken in 1915 in the article 
> below.  Gorgeous!  It also points out that color film photography 
> sacrificed some tonal resolution for color over black and white film.  HDR 
> can get all that back and go way beyond....  Of course the author also 
> poses the question of whether a dynamic range of 300:1 represents a 'sweat 
> spot' in our perception of color images.  To find the amusing answer, read 
> the article:->
>
> http://www.cybergrain.com/tech/hdr/
>
>
>  The Future of Digital Imaging - High Dynamic Range Photography
>
>>
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