Sunday, July 18, 2010

HDR Photography; Supplemental Post - Photography with Imre - Episodes 25, 25A, and 26

Well there are supposed to be thunder storms later this afternoon so I better get writing! I prefer to unplug my computer from the wall outlet to ensure any electrical spikes won't fry the system, even though I do have a battery backup in place. The last storm a day ago made the lights flicker; first time in recent memory.

I think I already said this, but I have to admit that I really enjoyed making these High Dynamic Range (HDR) photography episodes (25, 25A, and 26); I'm especially glad that I added episode 25A, as that clip demonstrated quite nicely how the camera can be setup to capture the multiple exposures needed to create an HDR image. Remember, even if you're using a different camera than the Olympus E-3 (as seen in the video), most have similar functionality, so I suggest checking your manual in order to discover how you can adjust those settings as well or use such features.

Now it is in those multiple exposures where the proverbial secret to creating great HDR photos lies. Although I expressed the importance of taking several shots at various exposure settings, I want to emphasize that the best results, at least according to some of the research I've done, can be achieved by ensuring that in the set of shots, at least two photos have been taken with one that has no pure black areas and one with no pure white areas. In other words, take at least one photo that is really over exposed to show detail in very dark portions of the scene and another that is quite under exposed to reveal detail in very bright regions; being as reasonable as possible of course, as under some conditions that may simply not be possible.

By having such shots, along with the several others in the "middle", you'll likely end up with a more balanced HDR image. For whatever reason, the first time I processed the gazebo photos I missed that I had a really over exposed shot with lots of detail in the shadow regions of the scene. You'll even hear my griping about it a little in the video (ep. 25) that I should have taken such a shot. But thankfully after reviewing my photos more carefully, I realized that I did have it (and you see this in ep. 26). As one would expect, the HDR image with the highly over exposed shot missing lacked detail in the shadow areas, whereas the other turned out much better; here's the properly manipulated image on my Flickr site (link to large size here):


The larger the tonal range of a scene (in other words, the greater the difference between light and dark regions), the more photographs you'll need between the two extreme exposures (over and under) for a better HDR image outcome. Adobe Photoshop's documentation recommends a minimum of three images, but five or more for better results. This is where bracketing may not always work and you'll need to use EV compensation or manual shutter speed adjustment, along with having to lug around a tripod to help ensure each shot is as identical as possible.

And if you "Like" my Facebook page, you may have noticed a question posted in regard to other HDR software products, to which I replied with some links to programs that do appear less pricey than Photoshop, or even free. Other than reading through the specifications of the programs, I haven't tried these out. They appear legitimate, but of course proceed with caution when downloading programs from sources you're not sure of. Here's the list of links:

http://www.hdrsoft.com/
http://www.hdrlabs.com/picturenaut/index.html
http://fdrtools.com/fdrtools_basic_e.php
http://www.imagingluminary.com/Default.aspx

Lastly, after three takes, I was finally satisfied with the length and content of episode 26, the Photoshop tutorial. I didn't point out one minor thing and that is in regard to the corner option. If you select a node, you can force it to become a corner via the checkbox, which may make it more suitable for your particular editing needs. Other than that, you create some nodes by clicking on the line and shift them up and down, or even sideways, to your liking. As I mentioned in the video, I personally aim to get an even brightness throughout the image. This does have the side effect of making the photo look a little flat or washed out, however once the pic is converted to 8 bit mode then I fiddle with the shot some more using the "regular" tools such as brightness/contrast, saturation, shadows/highlights, etc. to bring out the best in the photo.


And I just want to thank you all for your wonderful comments on my various sites, as well as for your suggestions (including other methods of creating HDR images). In regard to future video suggestions, I have the following requests written down:

  • Macro Photography
  • Lens Buying Guide
  • Landscape Photography
In the coming weeks you'll also be introduced to Gray Ghost, which will be featured in what I believe will be a very interesting photo episode, so do stay tuned for that. L8r!


Web Resources

http://www.cambridgeincolour.com/tutorials/high-dynamic-range.htm
http://www.cambridgeincolour.com/tutorials/dynamic-range.htm
http://help.adobe.com/en_US/Photoshop/11.0/WSfd1234e1c4b69f30ea53e41001031ab64-78eda.html
http://www.luminous-landscape.com/tutorials/hdr.shtml
http://en.wikipedia.org/wiki/High_dynamic_range_imaging
http://www.photoshopcafe.com/tutorials/HDR_ps/hdr-ps.htm
http://en.wikipedia.org/wiki/Tone_mapping

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