High Dynamic Range images

[misterx]

Photographing landscapes, I often run into the situation where the dynamic range of the scene is beyond what the camera can record. What I mean by that is that the brightest and darkest parts of a scene can't both be show at the same time. An example would be shooting a scene with details in shadow in the foreground, and a bright sky with clouds visible above the trees in the background.  If I expose the scene so I can see the details in the shadowy foreground, the sky gets so bright it is almost pure white, and the cloud details disappear entirely. If I expose so I can see the details in the clouds, the shadowy foreground turns black. 

The problem is, an outdoor scene might have a dynamic range of 100,000:1.  Our eyes have a dynamic range of about 10,000:1, and a digital camera can only see about 400:1.  So for many situations, you simply can't record all the detail that is there.

High Dynamic Range Imaging, or HDRI for short, is the process of programtically combining the information from several exposures into one. What you do is shoot several images, exposing them so you cover the full range of the scene. One shot for the darkest parts, one shot for the sky, and one or more to cover the rest.  This isn't "averaging" the exposures though, it's actually creating a new file with the full range of values. Unfortunately, that is more data than a jpeg or tiff can hold, so it has to be converted before it can be saved in a version compatible with today's software programs.

Enough blather!  I have made an example for you.  I created a high contrast situation by shining a 150 watt bulb on some white china in a darkened room. The upper shelf of the china cabinet has full light, and the bottom shelf has almost none. There is no way you can take one photo that captures it all.  So... I took three shots:



You can see the effect I described... the first one is lit correctly at the top, but too dark at the bottom. The last is correct at the bottom, but too light up top. The middle photo is ok in the middle shelf, but not at either end.

I then combine these, making various adjustments, and am able to produce a single image that captures all the detail:



It's far from a perfect example, but you get the idea. Anyway, I plan to do some experimenting with this more in the days to come, shoot some landscapes using this technique and see what I can do.

And for you digital imaging experts, yes, there are other ways to accomplish this. Exposure averaging, manually merging details in photoshop. But this is cooooler... 32-bit images baby. What can I say, I'm in touch with my inner geek.

Comments

[midendian.livejournal.com]

That's actually a pretty good example of a non-awful HDRI! :) So many people seem convinced once they discover HDR that shadows are totally bad and seek to remove all of them, creating ugly, cartoonish images that no one wants to see.

[quasigeostrophy.livejournal.com]

Nice proof of a concept a lot of people just don't seem to get. I just haven't had time to sit and play with HDRI image combinations, but I know I have a few I could try.

[zeppo-marx.livejournal.com]

I've tried playing with that once or twice, but have found it a very time-consuming and picky process that I really need to be in the mood for.

The results can, however, really be spectacular when done properly.

A couple of people I know swear by Photomatix as a tool to help create HDR images, and if I were into landscapes on a professional basis I would probably cough up the bucks to buy it. As it is, however, I'm still saving towards making the jump to SLR first.....

[tn-grrl.livejournal.com]

Very nice example. You explain it so that even we non-photographers can understand it. :) I can't wait to see what happens with your experimental landscape images.

*tee hee* dariens_haircut and I just discovered we're having simultaneous post readings over here. ;)

[midnightsrain.livejournal.com]

I wish I were experienced enough with a camera to know just what exactly it is that you speak of. I just point and click. *gasp* Someday I would love to learn all the intricacies of a really nice set up. But, thank you for sharing, I'm sure there are plenty of folks that will benefit from this info. Your photos always amaze me. Someday, I will make it through your entire gallery.

[rathgrith.livejournal.com]

I can see how this works with a still life, but how does it work if you have something that moves, like clouds or leaves moving in a breeze? Doesn't that cause problems when you combine the images?

[holyoutlaw.livejournal.com]

As others have said more than once already, this is a good example of an HDRI image that doesn't suck. At first I was real impressed with what people were doing, but the interest wore off quickly.

Here's the technique I use:

http://luminous-landscape.com/tutorials/digital-blending.shtml

the easiest technique, the Layer Mask.

Here are a couple pictures I've used it in:

http://www.flickr.com/photos/holyoutlaw/185836939/in/set-72157594178306054/

and the next two in the same photo stream.

This isn't what you're talking about here, I know, but thought you might be interested in case you didn't already know about it.

[ex-iam138.livejournal.com]

Nice detail. Yeh I'm gonna do that soon. I learnt about it at flickr. Apparently the plug in Photomatix helps. There is a HDR community at flickr. http://www.flickr.com/groups/hdr/