Tai Shimizu

iOS & Mac Developer

Creator of the iOS photography apps Gridditor & Filterstorm, the Mac drawing app Inkist, the Mac HDR app Light Compressor, and the experimental web browser Torii.

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High Dynamic Range

Everyone has an opinion on HDR, something I never really shoot. Most non-photographers love HDR imaging, but many photographers take issue with it. My opinion is mildly positive, depending on the image.

As long as HDR techniques are applied with a fairly subtle touch, it can add a lot to a photo, heavy handed images get old quickly. They may look interesting the first couple times you see them, but that feeling doesn’t last. I think this is where the schism between photographers and non photographers really lies, the novelty has worn off for photographers who have seen more.

Times Square — 24mm f/2 AIS @f/8 2 Exposures

http:  taishimizu.com pictures high dynamic range times square hdr thumb.jpg

This morning I spent a few hours in XCode writing an application that will combine 2 images into one, compressing the dynamic range. I’ve named my creation “Light Compressor”. High Dynamic Range is the word we normally use, but I think saying Compressed Dynamic Range is a bit more immediately understandable.

http:  taishimizu.com pictures high dynamic range LightCompressor thumb.jpg

Light Compressor is severely limited right now: it only combines 2 images, and there are very few options to tweak, but it does a pretty decent job for a Saturday morning’s work. Once you put in your two images, you set the “subtlety” (0 gives you a burned, overdone look, 10 is fairly close to being just a 50% opacity merge between the two). If you choose a lower, more agressive number on your first option, you can compensate for some of the harshness using the second parameter, which smooths the mask. Then you just hit save, wait half a minute (for a 12MP image) and it spits out a merged image and it even gives you the mask it used to combine them. Here we see the two input images on top, with the output on the bottom.

http:  taishimizu.com pictures high dynamic range comparison thumb.jpg

You can download the input images here and here if you want to try combining them in another app and see how it comes out. I’m sure you can get better results in Photomatix if you spend a little time with it. You may notice the output version here looks different than the one at the top of the page. I just bumped the saturation a bit and tweaked the curves to get that image.

I went down to Times Square (somewhere I normally avoid like the plague) to get these sample shots as, despite how much the crowds bother me, Times Square at night has a really challenging dynamic range to deal with. I think I’ve done a pretty decent job keeping the effect subtle while preventing a big chunk of the image from either being over or under exposed.

If anyone would like me to put some more work into Light Compressor and release it as shareware, leave a comment and I’ll consider it.

Posted by tai on 2010-01-16 20:41:35. Comments (0) | Tiny link

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