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The photo-blog of an entirely unknown photographer.
u n d e r e x p o s e d
Here I am, writing this blog post for the 3rd time. Let me explain. It's been a long time since my last entry (GASP! almost 6 months!). In that time this site got hacked (again), leading me to rewrite about 95% of the server side software. I liked most of the design, but I basically re-coded it from the ground up. The prior incarnation was built cleverly, but I left it so extensible that someone ELSE was able to add to my site. That was bad. I've also switched hosting companies, to save money and effort. However, those reasons aren't the reason I haven't added anything in a while. Generally my not posting means I haven't been taking pictures. Nothing could be farther from the truth. I've been so busy with photography I haven't had time to finish a couple of the scripts I needed to do in order to bring this site back online. Now, as I bring them back online, I'm curious how some of them ever worked in the first place. As I find more bugs in my scripts, I'm writing this for the third time because a nasty bug ate my prior 2 entries.
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So as mentioned, I've been doing quite a lot of photography recently! My alter-ego (not really) t.scudiero has been doing quite a lot of weddings this summer, booking weddings for next summer, shooting engagement sessions, making albums, and doing business development type things. That hasn't stopped me from doing casual shoots. Oh no. Like I said, I've been doing a lot of photography. In the coming days I'll be posting up some 'back-logged' entries from personal shoots across the last 6 months. We start today with one of my new favorite styles: High Dynamic Range (HDR) photography. I've dabbled in HDR in the past, but I've never been too happy with what I got.
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The supporting technology has gotten better and I've finally done some reading to the point that I understand what HDR is a lot better now. Here's the story. The human eye can see things that comptuer screens and prints can't display. The human eye can see up to 20 stops of contrast when properly adjusted to lighting conditions. That's obscene. A good DSLR camera can capture maybe 6 stops. Maybe. A print is more like 4-5 stops, and that's in bright lighting. Now most scenes don't HAVE 20 stops worth of contrast in them, but 10-12 is not uncommon. What typically happens is the photographer must choose which 6 stops to properly expose. Everything outside that range will be white or black. However, if we take 3-5 exposures, we can pick enough 6 stop ranges in exposure to have every detail of the image properly exposed in ONE of them. Doing this is called exposure bracketing and has been done for years, film cameras from the 1970s supported this.
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The difference comes in what you DO with those exposures. The magic of HDR is two steps. The first step is building an HDR image out of the multiple exposures. There are about a half dozen different algorithms for how to do this, the result of all of them is an image that you can't properly display on a computer screen nor print on any printer. Thus enters the 2nd step of HDR: tone mapping. Tone mapping basically involves doing _VERY_ clever things to map the huge dynamic range of an HDR image into the standard range and colorspaces. This is where a lot of the real magic happens, because if you 'over-cook' parameters in this phase you can get photos that don't even look like photos, they just look surreal. Sometimes this is a great effect, sometimes it's just wrong. If you tweak things just right, sometimes you can't tell it's an HDR at all, it's just a fantastically rich looking photo. The ironic thing about HDR photography is that it's precisely NOT high dynamic range: it's exactly the same as every other photograph on your PC display or in print. But rather than capturing just the slice of dynamic range that fits onto the print, we capture the full dynamic range, then compress it for the print. The music industry discovered this fantastic trick about the time CDs were becoming popular.
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So to get better at HDR photography I needed some high dynamic range scenes to shoot. I took my camera into downtown minneapolis and walked around for a day. The images here are the result. From arches under bridges to the fantastically beautiful old Minneapolis City Hall, I was quite pleased with the outcome. I have more to say about this, but this post is already way too long and I have much more to post in the coming days, now that my blog software has been repaired!
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