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Author Topic: PS CS2 Merge to HDR Question  (Read 3823 times)

Tim Gray

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PS CS2 Merge to HDR Question
« on: May 24, 2005, 12:44:27 PM »

Even with a tripod, I find that there can be registration errors of a couple of pixels from shot to shot so always use the align option. I've done a couple of dozen HDR shots (8mpx) - ranging about 4 to 6 frames with no "gotchas" on the align feature, other than it takes more time. My only concern would be the extent of the registration difference that can be accomodated. I suspect that scanned film could introduce registration differences significantly greater than shooting via digital. You could layer the shots and manually tweak the alignment then save back to separate files for HDR processing. Even then I'd probably still use align.
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dkusner

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PS CS2 Merge to HDR Question
« Reply #1 on: May 27, 2005, 10:52:50 AM »

I've done a little bit of playing with Merge to HDR and was surprised to notice that it creates files in sRGB color space, apparently without any ability to change this. It would be nice to tell it which color space to use, or to have it use the color space of the source files (or the default option in the raw converter).

Am I missing something -- can you use other color spaces or are you limited only to sRGB? I've primarily been converting RAW 20D CR2 files directly from Adobe Bridge.
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dkusner

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PS CS2 Merge to HDR Question
« Reply #2 on: May 29, 2005, 09:34:32 AM »

Quote
My guess is that your default workspace is sRGB. You should change that, you know.

I was about to write that my default workspace is ProPhoto, because that's what I convert my RAW images to, but upon thinking about it I probably do have default set to sRGB for various reasons. I'll try changing it and see what effect that has on Merge-to-HDR. That will probably resolve my issue, thanks.
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jimdesu

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PS CS2 Merge to HDR Question
« Reply #3 on: May 24, 2005, 01:07:57 AM »

Hi y'all,

I'm considering upgrading to Photoshop CS because of its "Merge to HDR" feature.  I don't actually care about the dynamic range aspect, but I want the ability to do image stacking for noise-reduction purposes.  Most of the programs I've seen that do this (aimed at astronomers) are designed to handle relatively small images, and would choke on my scanned 6x9 negs.  But Photoshop handles large files just fine, so the upgrade is tempting.

Has anyone made extensive use of the alignment feature of "Merge to HDR" and can vouch for it, or else mention caveats?

thanks,

James
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boku

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PS CS2 Merge to HDR Question
« Reply #4 on: May 24, 2005, 04:52:27 PM »

I tried it last night with 4 images - 7 frames each. It is essential. Slows you down, but really matters.

I tried Merge to HDR without the align and I was shocked at how much image drift I had. I really made me feel bad about what I had previously percieved as impeccable tripod technique. So much for that dream. I'd like to blame the registration errors on wind, but I know that wasn't the case.

I think the alignment feature works very well.

I hope you aren't considering this for Astrophotography work. Frame to frame celestial movement might be a problem and actually fight against this alignment feature.
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jani

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PS CS2 Merge to HDR Question
« Reply #5 on: May 29, 2005, 09:11:40 AM »

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I've done a little bit of playing with Merge to HDR and was surprised to notice that it creates files in sRGB color space, apparently without any ability to change this. It would be nice to tell it which color space to use, or to have it use the color space of the source files (or the default option in the raw converter).

Am I missing something -- can you use other color spaces or are you limited only to sRGB? I've primarily been converting RAW 20D CR2 files directly from Adobe Bridge.
This is strange, both my attempts at HDR from three images have resulted in using Adobe RGB. I have a 20D, too.

I have, however, been using File->Automate->Merge to HDR from within my CS2 demo.

I tried using Adobe Bridge to select three raw images and Tools->Photoshop->Merge to HDR. Result: Adobe RGB.

I then changed my default working space (in CS2) to ProPhoto RGB, and did another Merge to HDR from Adobe Bridge. Result: ProPhoto RGB.

My guess is that your default workspace is sRGB. You should change that, you know.

Considering another thread discussing ProPhoto RGB, I'm reconsidering my use of Adobe RGB. I've tried ProPhoto before, but I failed in making it work for me, so I went back to Adobe RGB.
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