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HDR, Panoramas and Tone Mapping Merging several different exposures into a single image

HDR exercise (Candle)

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Old 11-16-2007, 05:24 PM
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HDR exercise (Candle)

It seems to me a lot could be learned about HDR from a shared simple exercise. How about your camera on a tripod, and a candle on a table? Put a book or something else interesting with fine detail next to the candle. Light the candle, turn off all room lights (needless to day, do this at night), then take your 3-5 exposures, 1-2 EV apart. Assemble into HDR using your preferred technique, then post what you get here along with how you did it.
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Old 11-17-2007, 12:26 AM
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Re: HDR exercise (Candle)

Sounds like a good exercise Doug and I haven't tried really extreme HDR imaging with nighttime shots....shot in near darkness!....should be interesting
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Old 11-17-2007, 02:15 AM
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Re: HDR exercise (Candle)

Thought I would try a comparison (Granny says I go overboard!)


Shot with Canon S1Is (3mp)
from about 4 feet
200ASA
Custom White Balance using sheet of paper
2 stops up and down
Auto 3 exposure burst
~~~~~~~~~~~~~~~~~~

1
Middle/Normal Exposure

~~~~~~~~~~~~

2
HDR Photomatix
Default Tone mapping
Photoshop CS2
Levels
Gradient layer to even things out
NoiseWare
Lab sharpen


~~~~~~~~~~~

3
Photoshop CS2
Shadow/Highlight
Levels, Curves
NoiseWare
Hue/Saturation
Lab Sharpen


~~~~~~~~~~~

4
Photoshop CS2
History Brush Set to Screen
Levels, Curves
NoiseWare
Hue/Saturation
Lab Sharpen


~~~~~~~~~~~

My conclusion...

The candle flame looks better in HDR.. BUT.. this is maybe the third time I used Photomatix.. (could probably be much better in more capable hands)


Just using the History brush don't look bad to me!
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Old 11-17-2007, 02:43 AM
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Re: HDR exercise (Candle)

Good test. I can't see much exposure difference between 3 and 4, but 4 definitely looks smoother. 2 has so much color noise I can't get much beyond that.

With such a harsh specular highlight (the candle) there's not a lot of reason to underexpose. I was hoping the shadows being available in the midtone area might mitigate some of the noise, but perhaps this was a bit of a drastic test.

I'll be posting a test of my own, but I have to go tripod shopping first
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Old 11-17-2007, 06:19 AM
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Re: HDR exercise (Candle)

what did you do in 4 to get significantly less noise? You used noise ware in each case?
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Old 11-17-2007, 10:27 AM
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Re: HDR exercise (Candle)

Here's my attempt with my Nikon D80 / 18-200mm VR. I took these 3 images using manual focus:

Candle Test normal exp.jpg
normal exposure - f4.5 - ISO 100 - 1 second 31mm

Candle Test under exp.jpg
under-exposed - f4.5 - ISO 100 - 4/10 second 31mm

Candle Test over exp.jpg
over-exposed - f4.5 - ISO 100 - 6 seconds 31mm

Candle Test HDR Final.jpg
Final HDR image

I shot RAW images...don't know if that made much difference!...and then processed them in Photomatix using the default method. Finished off with some contrast tweaks in Photoshop and I cropped it a little.

Conclusion: I can only bracket for 3 exposures at +/- 2ev....maybe it would be more successful with cameras that can bracket more.....mind you, I used a tripod so I could have taken 5 bracketed images but I didn't think of it at the time. I really think though for successful HDR images you need a more equal amount of extreme highlights and shadows to get a better range.

Maybe tomorrow I'll try with 5 exposures and see if that covers the whole range.
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Old 11-17-2007, 11:07 AM
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Re: HDR exercise (Candle)

olbaldy - Would have thought you could get a lot smoother tone mapping than that with three exposures. I dont know Photomatrix. Why dont you just use Merge to HDR? even CS2 its good enough, you can output different layers into a 16 bit file using different mapping techniques one for localised detail and another for overall tone avoiding all the shadow noise. If you are using CS3 you can then read the file into camera RAW for nice high bit depth tonal work
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Old 11-17-2007, 11:15 AM
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Re: HDR exercise (Candle)

ChinaMark:

ISO 100 is more daring than I've been in my prelim tests
Good final result, though I'm still debating over whether I just like the 6 second exposure better by itself.

I do think a wider range with even EV steps might be helpful.
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Old 11-17-2007, 11:18 AM
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Hope you don't mind me borrowing your images...

...ChinaMark. I took your brightest version and copied the Darkest version on Top layer and ran a Dynamic Range Extender Script-fu on it. I then ran a Tonemap Script-fu to further enhance the piece. Finally, I took a copy of the original bright version and copied it to Top layer and set to Saturation and blended it down to taste.
Attached Images
File Type: jpg Candle Test over exp.jpg (92.6 KB, 137 views)
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Old 11-17-2007, 11:30 AM
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Re: HDR exercise (Candle)

Sounds like we might need a separate thread explaining Script-fu, or even a blog
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