HDR Storm Photography

[Ryan McGinnis]

Tonemapping from a single RAW file is quite doable with Photomatix, but be aware that in doing this, you are in no way creating an HDR image -- not even an HDR downsampled image. You're just tonemapping an LDR image to give it that overcooked look that people associate with HDR. Current digital SLR camera sensors cannot capture HDR images in one shot, and so it is impossible to create an HDR image from a single photograph. There are some high end medium format backs that can do HDR in one shot (I think), but you'd have to drop around 40 grand to get one.

 

[Darren Addy]

As we discussed in the original ST thread on HDR, it may be possible to extract +1 and -1 EV from a single RAW, but I think any such resulting images could not really be called High Dynamic Range imaging. (More like MDR: More Dynamic Range imaging). Pro photogs have been using RAWs for this purpose for years (bringing out hidden details in a "blown-out" wedding dress, for instance).

I think chasers might be interested in MDR images, in any event, because HDR isn't terribly practical for moving images. You have image shift occurring between each of your bracketed exposures (almost no matter how fast you can take them). So I'd rather be able to produce an MDR image from a single RAW than have a NDR (no dynamic range) image from a JPEG.

I think the term "HDR" has been sorta hijacked, and the precise don't appreciate it.
(Words Mean Things).

 

[Melanie Kern-Favilla]

There are some high end medium format backs that can do HDR in one shot (I think), but you'd have to drop around 40 grand to get one.

That's all?! Heck, I'll take two.



Mel

 

[James Langford]

Tonemapping from a single RAW file is quite doable with Photomatix, but be aware that in doing this, you are in no way creating an HDR image -- quote]

Well, I'm going to have to respectfully disagree with you here. Maybe we are just talking symantics. According to the wiki I found on HDR http://en.wikipedia.org/wiki/High_dynamic_range_imaging:

"high dynamic range imaging (HDRI) is a set of techniques that allows a greater dynamic range of exposures (the range of values between light and dark areas) than normal digital imaging techniques."

It is very easy to gain -1 and +1 stop from a single RAW image without losing much. Comparing them to a seperate exposure that is actually bracketted at -1/+1, I find very little difference in the final tone mapped image. To me, it is a tool just like anything else. It allows me to gain some shadow and highlight detail over what I would normally get in a processed RAW file. I could probably do similar things using Shadows and Highlights, or even using layers, but I prefer the look I get from Photomatix.

I generally prefer to shoot from seperately bracketted shots, but it is sometimes not practical. For the storm pano above, I didn't have time to bracket, as that image is a pano created from 6 source image. There would have been too much movement in the storm to stitch the shots later. The Grand Tetons shot is one from a long time back where I shot the original in RAW. I reprocessed using HDR techniques I learned in the past year or so, and liked the results. The other images are all bracketted exposues at -1/0/+1 EV.

Anyway, for those that are interested, there is a small summary on the HDR techniques I use in the next post.

James

 

[James Langford]

So, here is a quick summary on HDR tone mapping. Please note that I won't go much into HDRs themselves, as I don't really do much with them. I don't think many do yet. Maybe once HDR monitors are more readily available.

What this summary covers is tone mapping HDR images to create a final JPG image. There are many ways and tools to create tone mapped images. I use Photomatix to do it. Others use Photoshop, or something like Dynamic Photo HDR. My primary motivation is to compress more shadow and highlight detail into a single consumable JPG image than would normally be there. I enjoy the artsy look that this gives, and it is kind of my style. Others like to create very contrasty images. To each their own.

The first step to creating a final image is to start with an HDR image. This requires having several images at different exposure levels. You can either do this by bracketing a single image at multiple exposures, or you can start with a single RAW file and pull multiple exposures out of it. I think you will generally get better results by bracketting multiple exposures, rather than using a single RAW. However, it is not always practical, especially if things in your scene are moving (like clouds, people, etc).

Mutliple Exposures: An easy way to get mutliple exposures is to use your camera's bracketting feature to capture 3 exposures of a single scene. You probably want to do -1/0/+1 at least, and maybe even -2/0/+2. You can also manually bracket using Manual mode, and there is no reason to not do more than 3 exposures (ie -2/-1/0/+1/+2). I'm no expert here, so maybe others can share results with a wider range of exposures. I generally bracket at -1/0/+1.

Singe RAW File: Using Adobe Camera RAW, or any other RAW processing program, you can easily pull -1/0/+1 expsores out of one RAW. Simply adjust the "Exposure" dial to -1, and then save the image as a jpg or tiff. Next set it to 0, and then +1 and do the same. Save them as seperate file names, like image-1, image-2, image-3 so they can be combined in Photomatix later.

Working in Photomatix: Pull your mutiple exposures files into Photomatix to create an HDR image. This will look really funky and overprocessed. Choose "Tone Mapping" to bring up the mapping window where you adjust everything. I would suggest spending a lot of time playing around here to learn what different things do and how they affect the image. Here are my general settings to try and create a fairly realistic image:

Strength: 65 to 70
Color Saturation: 70
Light Smoothing: All the way to the right, maybe one click left
Luminosity: -2
Microcontrast: All the way to the right
Microsmoothing: 0 to maybe 15 depending on the image
White Clip: 0 I use Photoshop to adjust this
Black Clip: 0 I use Photoshop to adjust this
Gamma: 1.20 (I think this is standard gamma?)

Anyway, that's what I do. I'd be interested in seeing anyone elses settings, and examples of the output.

James

 

[Brandon Goforth]

I tried out some HDR the other day and my photos sucked. I had 3 pictures I was blending in HDR (using Photoshop CS3 Extended) and they were each 1 1/3 stop apart. I tried several time to make it work but I kept getting dull results...and "hazy" looking pictures. It looked a lot better whenever I just post-processed the single image with correct exposure.

 

[James Langford]

Personally, I have had pretty bad luck with HDRs in Photoshop. I know Ryan McGinnis uses CS3, and his look amazing. Maybe he can explain his process to us?

James

 

[Ryan McGinnis]

Well, I'm going to have to respectfully disagree with you here. Maybe we are just talking symantics. According to the wiki I found on HDR http://en.wikipedia.org/wiki/High_dynamic_range_imaging:

"high dynamic range imaging (HDRI) is a set of techniques that allows a greater dynamic range of exposures (the range of values between light and dark areas) than normal digital imaging techniques."

While in some sense it's a question of semantics, in others it's a question of actual process.

The semantics issue is thus: when people correctly refer to HDR images, they are referring to one of two things. They either mean "a 32 bit floating point file containing a wide range of dynamic range information", or they mean "An 8 or 16 bit JPEG or TIFF file that has been generated (usually by tone mapping) from a 32 bit floating point file containing a wide range of dynamic range information." Some would argue that the second definition above is also inaccurate, and they're probably right, but I think that's a lost battle.

When people incorrectly refer to HDR images, they usually are referring to it in the following way: "An 8 or 16 bit JPEG or TIFF file generated by tone mapping a single 8, 12, or 14 bit JPG or RAW image capture." Specifically, they usually mean "all my normal photos that I ran through Photomatix".

A RAW image generated by the typical 12bit or 14bit SLR camera sensor capture contains less dynamic information than a slide or a film negative. True HDR images, saved as a 32bit floating point files, don't even render correctly on current monitor technologies, as they contain more dynamic range than the monitor is capable of displaying. (Some companies are working on developing new monitors, and I suspect in the next decade HDR monitors will become more inexpensive and common.) They're saved as 32 bit floating point files because the amout of tonal information they contain won't even fit inside a 16 bit TIFF.

Tone mapping is an entirely different thing than HDR,; tone mapping is an attempt to get an HDR file to render correctly and more accurately on current monitor technology or prints. You can tone map any kind of file, however -- you can tone map a JPEG, but that doesn't magically make it HDR. Indeed, most all of us manually tone map things when we post process our images, either via the dodge/burn tool in Photoshop or through adjustment layers.

I'm not sure what the cutoff point of dynamic range would be to differentiate between "high" dynamic range and normal dynamic range imaging, but I think there has to be a cutoff somewhere, otherwise the term HDR has no meaning. I've shot some HDR scenes where I used around a dozen photos at 2 stop brackets. That's 24 stops of latitude in one image -- well beyond what could be saved in a 16 bit TIFF file or rendered on a monitor. I think RAW files fall well short of that cutoff, as do the creators of Photomatix, the program you're using to create your tone mapped images.

 

[Ryan McGinnis]

Personally, I have had pretty bad luck with HDRs in Photoshop. I know Ryan McGinnis uses CS3, and his look amazing. Maybe he can explain his process to us?

James

Thanks for the compliment! I've got a tutorial up here:

http://backingwinds.blogspot.com/2006/10/how-to-create-professional-hdr-images.html

 

[Jim Saueressig]

Cannot let this thread die!! LOL

November 16, 2008 - Deep colors after the sunset over John Redmond Reservoir. HDR

 

[Jim Saueressig]

A few more tries from last nights sunset. So far I have had no luck with taking previous shots that were not bracketed and getting that distinct HDR look from them.