Balancing Exposures and HDR workflow  

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mark_anderson_us
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Balancing Exposures and HDR workflow

by mark_anderson_us » Fri Jan 02, 2009 4:01 pm

Hi All

I took a bunch of shots last week in New Orleans using fixed apperture and AEB (EV: -2,0,+2). The f-stop range is 1/15 to 1/100 across the entire range.

I wanted to use an HDR workflow, but am not having a lot of luck. I tried bringing the raw files into APP and using optimize by layer and also using a yellow anchor on one image and setting the rest to red. I've also tried with different color correction methods.

The result always has vertical bands of darkenss due to the different exposures (see attached). I'm not entirley sure I'm using the anchors correctly. If I use 1 yellow (on each layer) and red everywhere else, where should I put the yellow one? (the darkest, lightest or other image)

Ideally, I'd like to use the bracketed shots in APP and get one HDR out that I can tone map, or 3 images that I can create an HDR from in photomatix. I could live with batch creation of HDRI's in Photomatix and then stitching these (upside is that it can fix ghosting on blended image); however, I think I read that smartblend does not work with HDR and the HDR's lose the EXIF info (lens and aperture).

Can anyone share what works for them when using HDR/bracketed shots?

Should I use a fixed aperture and shutter speed for each bracket (i.e. set to manual instead of aperture priority) when creating HDR?

How are people metering for HDR? I'm thinking using an incident reading from handheld meter and fixed aperture and shutter (with +2/-2 EV) may be best

Is it better to use photomatix first?

Thanks in advance

Mark


Last edited by mark_anderson_us on Fri Jan 02, 2009 4:07 pm, edited 1 time in total.
Canon EOS 30D with BG-E2 grip
50mm f1.4, 16-35mm f2.8L, 28-70mm f2.8L, 70-200mm f2.8L, 100mm f2.8 Macro
Gitzo 2531, Merlin/Orion

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digipano
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by digipano » Fri Jan 02, 2009 4:33 pm

Switch the color correction to NONE & output 3 layers which you can then manually blend into HDR & tonemap.

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mark_anderson_us
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by mark_anderson_us » Fri Jan 02, 2009 5:09 pm

If I do that how will the frame to frame exposure balancing get done? Isn't that part of color correction?
Canon EOS 30D with BG-E2 grip
50mm f1.4, 16-35mm f2.8L, 28-70mm f2.8L, 70-200mm f2.8L, 100mm f2.8 Macro
Gitzo 2531, Merlin/Orion

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digipano
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by digipano » Fri Jan 02, 2009 5:21 pm

For HDR you dont need do that.
I shoot manual HDR bracket & then feed all the raw images to APP & switch the layers (Sort by speed) now it will show you & stitch the speed named layers
eg: 1/15
1/60
1/250

then I take the stitched image into HDR software.

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mark_anderson_us
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by mark_anderson_us » Fri Jan 02, 2009 5:25 pm

I'm confused. In each layer I have varying shutter speeds (fixed aperture) because I've got auto exposure (Aperture priority set), so are you saying I shouldn't use this method with HDR?

If I use a fixed aperutre and shutter speed for each layer, wouldn't I get even bigger frame to frame differences (as some would be way more over/under exposed)?

Regards

mark
Canon EOS 30D with BG-E2 grip
50mm f1.4, 16-35mm f2.8L, 28-70mm f2.8L, 70-200mm f2.8L, 100mm f2.8 Macro
Gitzo 2531, Merlin/Orion

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digipano
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by digipano » Fri Jan 02, 2009 5:34 pm

mark_anderson_us wrote:I'm confused. In each layer I have varying shutter speeds (fixed aperture) because I've got auto exposure (Aperture priority set), so are you saying I shouldn't use this method with HDR?

Oh then you are stuck, you should not have used aperture priority, if for any reason I use aperture priority then I lock the exposure for the entire series, Its always better to shoot on Manual mode, that's what I understood when you said fixed aperture.

You locked the aperture but forgot to lock the exposure & speed varied in each case thus giving you the problems now in blending.

If I use a fixed aperture and shutter speed for each layer, wouldn't I get even bigger frame to frame differences (as some would be way more over/under exposed)?

The reason you are doing HDR is bcoz the scene has huge brightness range so bigger frame to frame differences will not matter, you just need to ensure that you cover the brightness range.

I normally bracket -2/0/+2
but at times I have to do -4/-2/0/+2/+4

What you can try is separate the images now & stitch them 1 by 1 using the auto color correction & then try blending HDR. In this case you still will have some banding due to APP making corrections differently in each series of exposures.
Last edited by digipano on Fri Jan 02, 2009 5:39 pm, edited 1 time in total.

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mediavets
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by mediavets » Fri Jan 02, 2009 5:37 pm

Can you group by bracket?
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Many different Nodal Ninja and Agnos pano heads. Merlin/Panogear mount with Papywizard on Nokia Internet tablets.
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mark_anderson_us
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by mark_anderson_us » Fri Jan 02, 2009 5:43 pm

Thanks for replies guys.

I did group by bracket on one test and used optimize by layer.

Digipano, one of the key features of APP is that it can handle the varying exposures between frames, which was the reason I used aperture priority. However, I think I'll try the method you suggested next time.

I'll also try stiching each bracket individually and see what happens

Regards

mark
Canon EOS 30D with BG-E2 grip
50mm f1.4, 16-35mm f2.8L, 28-70mm f2.8L, 70-200mm f2.8L, 100mm f2.8 Macro
Gitzo 2531, Merlin/Orion

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digipano
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by digipano » Fri Jan 02, 2009 5:50 pm

mark_anderson_us wrote:one of the key features of APP is that it can handle the varying exposures between frames, which was the reason I used aperture priority.

Yes but that's good when you have only single series of images not on HDR with auto correction switched on.

Think it this way why would you need HDR if APP can make the correction the low lit areas & bright lit areas will automatically get in range if you bracket enough on both sides.?

I tried this once on HDR & it gives the same problem what you are facing, but in my case it was just a test shot to test APP blending.

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mark_anderson_us
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by mark_anderson_us » Tue Jan 06, 2009 2:35 am

Hi Guys

Finally nailed my workflow and produced a decent pano from HDR images:

http://www.anderson-mark.com/photos/default.aspx (chicago at dusk). Interactive version takes a while to load, but you can zoom in a lot.

1. Shot with EOS 30D and 16-35mm f/2.8L (at 35mm) on tripod.
2. 2 rows with 7 shots per row (bracketed +-EV2)
3. Created HDR in Photomatix
4. Stitched in APP (No Color Correction, Output HDR)
5. Tone Mapped and cooling filter applied in Photoshop CS4
6. Flash created with Pano2VR

Can't wait to get a Merlin! (Unless the DSLR Gigapan is available soon)

Thanks for all the advice

Mark
Canon EOS 30D with BG-E2 grip
50mm f1.4, 16-35mm f2.8L, 28-70mm f2.8L, 70-200mm f2.8L, 100mm f2.8 Macro
Gitzo 2531, Merlin/Orion


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