insights from PhotoMatix experts...?

[kvon]

Hello,

 

I’ve been playing around with HDR, evaluating the software tools that are out there. Have played with Photomatix

& TuFuse Pro so far. Have had some frustrations, because I sort of expected that there would be a magic bullet

regarding how to get these tools to produce a presentable result. In reality of course, it seems that you just

gotta diddle with the knobs until it looks right. I’ve had mixed results with this, and will need more

experimentation before I decide if one or both of these can consistently give me results that I like. In the

meantime, I’d sure appreciate some insights from anyone who’s experienced with this software & techniques. A few

questions regarding specific problems I’ve had:

 

1) Regarding the clarity of the final resulting image, assuming that I do everything correctly: begin with crisp

clear images that have alignment differences that are slight enough that PhotoMatix’s native alignment correction

algorithm can handle it – if I do all this should I expect that the clarity of the resulting image will be

comparable to the clarity of the originals?

 

2) Is it pretty much expected that you’ll have to do some post-processing with the PM result to tweak the

contrast, sharpening, etc, or should I be able to get a “deliverable” right out of PhotoMatix?

 

3) Should I expect PM to “cry uncle” and give a degraded result if I push the limits with a) number of images

used, or b) dynamic range of those originals? I ask this because I tried an indoor scene with sunlight windows –

had a dynamic range of about 1000:1 (exposure range 2 sec – 1/500), which I covered with 6 images. Had a

terrible result – ghosting, exaggerated chromatic aberration & other funky artifacts. (Sample shown somewhere

here, if I can get this to work). Also couldn’t get the sky visible out the windows to look right at all (very

high end of the dynamic range). Did another scene with only 3 exposures (+/- 2EV) and got a very satisfactory

result.

 

4) Here’s a sample of a 3-exposure scene. Would like some objective feedback as to how “real” this looks… One

of the challenges with this stuff is balancing the local contrast & global contrast so that the image is

appealing but still realistic (not “overcooked”). I’m still developing an eye for that sort of thing, would

appreciate hearing some perspective…

 

Thanks, looking forward to some good info...<div></div>

[Craig_Cooper11664875449]

Youve managed to get the reflection of the sky in the water brighter than the actual sky which doesnt happen.

[roger_smith4]

I use Photomatix with three bracketed exposures myself- I don't find more useful. I use the shadows and highlights-adjust mode (I think). I find that it outputs a passable if somewhat flat image which I then work on more in Photoshop. I avoid HDR and tonemapping- it's a challenge to keep it natural looking. I think the folks at Outback Photo do tonemapping as an adjustment layer- definitely check out their tutorials.

[kvon]

Samples of the bad PhotoMatix result (with 6 input images) are here:

 

http://www.photo.net/photodb/folder?folder_id=857014

 

(Couldn't see how to get multiple images uploaded in a single message)

[rob_piontek]

Probably if you look at your images that are exposed for the interior there are some bad artifacts coming from the strong window light. These would naturally show up in the final HDR image. If you aren't already, try a lens that is good with CA, flare, and ghosting. If you aren't already, try stopping down to reduce this. If these things are a problem, I could imagine that it might effect the alignment of the images.

 

I like your image, it's nice, but I also noticed the bright reflection.

 

I had similar problems before, and ended up deciding that blending the exposures by hand in Photoshop gave me better results. But doing it with 6 brackets would be a pain.

 

You might also check out enfuse, it's free, and some people really like it.

[roger_smith4]

Try not doing this with HDR and tonemapping but blending multiple images- you should be able to avoid the halos and artifacts this way.

[kvon]

This is all great info - I appreciate everyone's feedback.

 

I've tried some of these things, again with mixed results. (This is maddening - you tweak one thing, and another

feature is thrown out of whack. Kinda like trying to hover a helicopter...)

 

Good point about the reflection lighter than the sky - I hadn't noticed that. Not so easy to fix it turns out.

I've compared the 3 different methods available in Photomatix, and TuFuse Pro as well. I guess this is an

example of where the global tonal hierarchy is violated... and I've read that it's a known caveat with the local

adaptation method (which was indeed the method used to generate this image). If I understand it correctly, the

only way to assure this doesn't happen is to use a global tone compression algorithm. So I tried this in

Photomatix, and it worked - except that the nice local contrast between the clouds & the sky suffered. So like

everything else I guess -- it seems to be a matter of compromise. Drat.

 

Rob - about the lenses, artifacts & stopping down: I don't have a lot of lenses to choose from, but I thought my

primary was a pretty decent lens (Canon EF-S 17-85MM f4-5.6 IS USM). At any rate, I stopped down from f8 to

f16, and the results were indeed way better - with regards to the artifact around the windows. However it

introduced some pretty bad lens flare. Maybe I can play around with the viewing angle to get rid of that...?

 

Roger - I tried the blending method in Photomatix, but ran into a major problem that I was unable to fix... With

such a high DR of this particular scene (brightly lit sky outside the window to shadows inside the room), I

couldn't get the sky to not appear washed out. Looking for some saturation there & just coudn't get it. The

other 2 tonemapping approaches didn't seem to have that problem.

[jwarthman]

Good information here already.

 

Also, if you're interested in a good HDR tutorial, I highly recommend Ben Willmore's (free) podcast (Pixel Perfect episode

92 - HDR Secrets):

 

http://revision3.com/pixelperfect/hdr/ (part 1)

 

http://revision3.com/pixelperfect/hdrpartii/ (part 2)

 

Enjoy!

 

-- Jim

[kvon]

Thanks Jim - I checked out Willmore's tutorial, definitely one of the best I've seen. I tried the PS masking

technique to tune down the reflections in the water, that worked quite well. (If I worked in PhotoShop more I'd

probably have thought of that on my own). FWIW I just upgraded to Lightroom 2.0, which with its

adjustments brush, sort of makes this particular function in Photoshop obsolete.

 

I've put up some other HDR test shots on my website, would welcome any feedback at all:

http://kwvv.net/Galleries/index.php