CS2 HDR advice?

ZP
Posted By
Zane_Paxton
May 16, 2005
Views
617
Replies
16
Status
Closed
Just curious if any of you have been experimenting with the new HDR tool. So far I have been very disappointed in the results… The images are coming out rather muddy and with odd colors that look like they have been brightened or darken too much…

Any thought, tips or guidelines how to get the best out of this tool?

My first analysis/theory is that it prefers a very dark and one very bright image at each end of the tonal range. On studying the examples in the video tutorial that comes with CS2, the extreme exposures are way, way more extreme that I would normally consider trying (as there wasn’t any point to doing that before). Without that it doesn’t have much to work with. In other words if the base images are too close in terms of exposure the tonal range isn’t wide enough to start with.

I also suspect that 2 stop exposure compensation is more useful than 1-stop exposure compensations.

Also, one image I was working on has very specific hot spots from the sun on a waterfall with the rest of the image pretty much in shadows. The shadows looked terrible (muddy) and the hot spot remained blown out no matter what I did with the 32-bit to 16-bit conversion…

Any insights and advice are appreciated!
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RB
Robert_Barnett
May 16, 2005
For me it doesn’t matter how bright or dark the images are they still come out muddy. I end up having to convert them to 16-bit and using curves and levels on them. The only exposure adjustment tool you have in 32-bit mode is "exposure" and it quite frankly sucks. Adobe since they added this to Photoshop needs to develop a 32-bit levels and curves command. Otherwise HDR is somewhat pointless at this stage. Though I am sure others will disagree. Muddy images just aren’t my thing and if I can’t exposure and color correct them in 32-bit mode then creating a 32-bit images just to have to down it to 16-bit to get the exposure and color I want is a big waste of time.

Robert
ZP
Zane_Paxton
May 16, 2005
Hi Robert,

So what you are saying is that HDR is a "BETA" or a "Version 1.0" at best to respond to marketplace demand.

I found this recently as a point of comparision that might be interesting: <http://www.hdrsoft.com/images/cs2/comparison.html>

Cheers,
RB
Robert_Barnett
May 17, 2005
I don’t know if I would say that. I mean it works. But, I think what is missing that is very much needed and probably should have been updated for it in CS2 is levels and curves. If these two options worked in 32-bit mode I would have no complaints about HDR images. I think they offer some real benefits. But, having to convert to 16-bit mode to get the exposure/color adjustments I need is a real downer and kind of defeats the purpose of 32-bit. It would be nice if I could do these corrections with the most image data possible and then convert down. I am hoping and praying that CS3 will levels and curves in 32-bit mode. I am not after and at this time don’t see a need for all of Photoshop’s tools in 32-bit mode. Though in time 32-bit may become like 16-bit and the need for all of Photoshop’s tools will become a major requirement. But, not now 32-bit is too cutting edge for that.

On this front, I think it is time that all of Photoshop work in 16-bit mode. I am hoping this comes about in CS3.

BTW I do give kudos to Chris and Adobe for the HDR. I think it is a fairly good first step.

Robert
CC
Chris_Cox
May 18, 2005
HDR is not a beta – but it is a 1.0. HDR is very much a technology in the research stage – but many people are using it, and we needed to start adding support. The folks using it daily (mostly special effects/film users) find the existing features pretty useful.

Unfortunatley, Levels and Curves don’t make any sense in HDR images – so we can’t make levels or curves commands. Exposure and gamma adjustments do make sense – so I added a new adjustment just for HDR use.

Zane – That comparison used default curves and didn’t bother to modify the tone mapping for the particular image. And it looks like a poor choice of radius as well. Hardly a fair comparison. Every image needs very different toning curves, and the optimal settings depend a lot on how you want the final toned version to look.
ZP
Zane_Paxton
May 18, 2005
It sounds like you know HDR pretty well; maybe an Adobe employee?

Is there any way to get some sort of tutorial/guidebook, etc that would help me (and others) understand the ins and outs and how to best use this tool?
CC
Chris_Cox
May 18, 2005
Yes, I’m one of the Photoshop engineers, and I wrote the HDR code (other than MergeToHDR – that was John Peterson).

Try <http://www.luminous-landscape.com/tutorials/hdr.shtml> for a quick intro.
C
Ciaran
May 19, 2005
Hi Chris,

Could you give a quick explanation of how the colour profile system deals with HDR images? If I load an EXR file and assign a profile I can see it’s doing something, but I’m not sure what.

How are values outside 0-1 handled? Am I going to be able to do what I want (apply profiles to linearised cineon images).
C
Ciaran
May 19, 2005
On closer inspection, I don’t think it’s doing anything at all.
CC
Chris_Cox
May 19, 2005
It’s converting the profile to a matrix/TRC profile and changing the TRC to gamma 1.0, then doing the conversion (because HDR images can’t handle all profiles).

Values outside 0-1 are handled as-is, we’re using floating point values.
C
Ciaran
May 20, 2005
So a 3d lut profile won’t have any effect at all?
CC
Chris_Cox
May 21, 2005
A 3D LUT will be approximated by a matrix profile, then converted to gamma 1.0. (HDR values can’t use the lookup table)
ME
mike.engles
May 21, 2005
Hello

Is it possible to use HDR with scanned images at different settings?

Mike Engles
MD
Michael_D_Sullivan
May 21, 2005
Whether or not HDR was intended to be used with different scans from a single slide/negative, it definitely can be used with them. My experiment with this approach can be seen here <http://avogadro.smugmug.com/gallery/503568/1/21287549>.
KS
Ken_Storch_(aka_photon)
May 23, 2005
Michael,
How did you achieve "telling HDR that they were 4 EV apart in exposure"?

Thanks
CC
Chris_Cox
May 24, 2005
Mike – it’s possible, but you’ll have to enter the exposure values manually.
MD
Michael_D_Sullivan
May 24, 2005
Yeah, I made them up, four EV apart; there weren’t any EXIF exposure values, so Photoshop asked me and I lied. It worked fine. The three scans were of only shadows, only midtones, and only highlights (using the Nikon scanner software’s levels- or curves-like controls).

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