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Author Topic: CS5 HDR processing-what is going on??  (Read 2274 times)
mdijb
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« on: September 30, 2012, 07:18:24 PM »
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I started sending a set of images from LR 4.2 to CS5 for hdr processing, and then bringing back the image into LR4.  Initially, the images generated by CS5 looked awfull, but when returned to LR, they looked very different --there is no relation between how the image appeared in PS after processing and what appeared in LR4.  After using LR adjustment, the images looked very good and realisitic without that HDR grunge look

SOmething has changed

I have tried the same process on series of recent images and the image generated and viewed in CS5 looks extremely dark.  WHen returning this to LR the image looks the same instead of a more realistic rendering I was seeing before--it takes about 6 stops of increased exposure to get started--this is a change in behavior and the results are not pleasing at all.

Has anyone else seen this and is there an explanation for this apparent change in behavior?/

MDIJB
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aduke
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« Reply #1 on: September 30, 2012, 07:41:04 PM »
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I've seen this, so its probably not some sort of error. Unfortunately, I can't help with an explanation. Angry

Alan
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kencameron
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« Reply #2 on: September 30, 2012, 08:03:09 PM »
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If you are doing 32 bit HDR in photoshop, then the way it looks after the merge can be adjusted using a brightness slider but that only impacts on the preview. It is useful to give you an idea of the dynamic range that is available but makes no difference to the file that comes back into lightroom. Not sure if this has any relevance in your case.
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RFPhotography
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« Reply #3 on: September 30, 2012, 09:39:11 PM »
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Are you tonemapping in PS or just sending the 32 bit file back to LR?
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kirkt
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« Reply #4 on: October 01, 2012, 09:44:44 AM »
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There could be a few potential things that cause the difference.

LR4.2 (and its ACR counterpart) can accept 32bit TIFF files and usually effectively tonemap them with fairly extreme adjustments to the Highlight/White and Shadow/Black sliders.  So if you send the image sequence to PS for HDR merge and then, while still in 32bit, send the file back, LR4 I suppose will not complain.

In PS there are a couple of ways to adjust the preview of a 32bit file so that you can inspect portions of the overall dynamic range on your display.  One is the 32bit preview slider in the bottom left hand corner of the application frame (1 in the attached screenshot).  The other way, with more options, is the menu item "View > 32 bit preview options" (2) - I believe that when you adjust your preview in the Merge to HDR Pro dialog, the settings in the 32 bit preview options get changed.

In other words, make sure both of these preview settings are zeroed before you send you file back to LR or the preview may look very different than the actual file.  These only apply to 32bit files - once you change modes to 16 or 8 bit, the adjustments you make on the HDR toning dialog that appears will be applied and the preview is no longer an issue.  It sounds like you are sending a 32bit image back to LR, which LR4 will accept, but the preview in PS differs from what LR displays.

When you say "something has changed" - this support for 32 bit TIFFs came in LR4.1, I believe.  Here is a short blurb from HDRLabs about it:

http://www.hdrlabs.com/news/index.php?id=2782449297503966307

and from John Nack's blog:

http://blogs.adobe.com/jnack/2012/04/lightroom-4-1-adds-hdr-toning-support.html

kirk
« Last Edit: October 01, 2012, 10:00:33 AM by kirkt » Logged
mdijb
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« Reply #5 on: October 01, 2012, 07:07:40 PM »
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Generate the HDR file->View->32 bit preview options-> Moving the Exposure slider changes the appearance of the Image.  However when sending back to LR it is much darker than the Preview image--several stops.  The darkness of reimported image can be altered by moving this slider but is still very different from the preview.  In addition the colors are oversaturated and unatural compared to the preview image.  The apprearance of the preview looks good to my eye but the reimported image looks awfull.

In addition, an annoying problem is that when reimporting back to LR, the image ends up at the very end of the film strip or on the bottom of the grid, instead of ending up next to original images.  YES the option to "stack with originals " is checked on.

ANy other suggestions??
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RFPhotography
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« Reply #6 on: October 01, 2012, 07:29:31 PM »
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OK, so you're importing the 32 bit TIFF back into LR.  What is happening, why the image is much darker, is that LR is altering the white point of the image.  If you look at the 32 bit preview options the exposure is likely set to some level above 0.  Move it back to 0.  That's what LR is doing.  Then the two should look the same.  Import the image with the adjusted exposure set to 0 into LR and it will look the same as it did in PS.

Can't help you on the oversaturated colours, that's not something I've experienced.

When I import the image back into LR, it ends up stacked right after the original bracketed sequence.  Stack with originals shouldn't even come into play.
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kirkt
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« Reply #7 on: October 01, 2012, 08:47:38 PM »
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For fun, try this:

Once you have performed your merge in PS, set the Preview slider and View >HDR preview options all to 0.  Add an Exposure adjustment layer above the Background HDR image.  Increase the Exposure by a couple of stops, or whatever gives you a decent looking tonal representation.  This adjustment will actually alter image data, not the preview.  Now flatten the image and send it back to LR- how does the image look in LR?  Same as the preview in PS with the Exposure adjustment?  It should - the Preview was zero'ed and the Exposure adjustment was actually applied to the data, not a preview.

kirk
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RFPhotography
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« Reply #8 on: October 01, 2012, 09:41:09 PM »
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What's the need to do that though?  The same thing can be done in LR with the Exposure control.  The actual image isn't changing.  Just the preview. 
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kirkt
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« Reply #9 on: October 02, 2012, 09:27:58 AM »
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Sure - I was trying to get the OP to understand the difference between adjusting the preview versus adjusting the data.  I don't use LR4, but in LR3 the Exposure slider only permitted +/- 4 stops - I notice that in ACR7 that has been changed to +/-10, so you probably would not need to boost the base exposure in PS - however, if you ever found that LR was not giving you enough range to boost the exposure, you could do it in PS before sending the file back to LR.

It was more of an demonstration than suggesting that the OP needed to make any adjustments to the file data in PS.  I hope I did not cause any confusion.

In terms of your LR preview looking awful, can you give us a screenshot?  What files are you merging to HDR in PS?  Have you acquired them correctly (i.e., not in Auto White Balance?) and across the full DR of the scene?

kirk
« Last Edit: October 02, 2012, 09:30:52 AM by kirkt » Logged
RFPhotography
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« Reply #10 on: October 02, 2012, 10:43:30 AM »
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You have the same +/-10 with 32 bit files in LR 4.1 and later as well.
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kirkt
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« Reply #11 on: October 02, 2012, 01:11:45 PM »
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Also have a look at this interesting technique tip to preprocessing your raws in LR for HDR merge:

http://www.hdrlabs.com/news/index.php?id=1276328416487110799

kirk
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RFPhotography
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« Reply #12 on: October 02, 2012, 02:00:28 PM »
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Another option is to apply a linear render curve via a camera profile which will eliminate the default render curve in the Adobe Standard profile.  Alternatively, you can revert to the 2010PV which doesn't have the same highlight recovery strength as the 2012PV.
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BartvanderWolf
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« Reply #13 on: October 02, 2012, 02:19:08 PM »
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Alternatively, you can revert to the 2010PV which doesn't have the same highlight recovery strength as the 2012PV.

Yes, I agree, if one is pre-processing images for HDR file assembly, a predictable response curve can be much easier distilled from PV2010 source files, or from linear gamma output. However, if one prefers to use exposure fusion as a tonemapping method, then I would optimize the individual exposures with PV2012 or others.

Cheers,
Bart
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kirkt
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« Reply #14 on: October 02, 2012, 03:40:24 PM »
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Another option is to apply a linear render curve via a camera profile which will eliminate the default render curve in the Adobe Standard profile.  Alternatively, you can revert to the 2010PV which doesn't have the same highlight recovery strength as the 2012PV.

If you use a QP202 or similar QP card for making dcp profiles, the active profile you are constructing is saved as a linear "temp" working dcp in the QPCalibration library support directory.  You can copy this linearized version to the Camera Raw camera profile directory and use it to make linear files from ACR/LR for HDR merge.

Kirk
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RFPhotography
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« Reply #15 on: October 02, 2012, 09:31:07 PM »
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Yeah, sure.  A QP card could be used.  I use a Color Checker 24 patch card and DNG PE.  Whatever way it's done, the point is that profile can be used to eliminate the 2012PV default render curve.

Bart, yes, for non-32 bit exposure fusion doing some additional pre-merging work is probably a good idea.  I was talking about HDR in reference to Kirk's link to the HDRLabs site with the advice from Christian about adjusting exposure and contrast before doing the HDR merge.

I regularly use RAW files exported out of LR to Photomatix without adjusting anything (except WB and lens distortions) and don't find a significant difference between results using the 2010PV.  I'm not finding an unacceptable compression of highlight tones.
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