How-To: iPhone HDR

The iPhone (s aapl) has a great little camera, but it’s got serious limitations. Anyone who’s ever tried to capture a scene with a wide range of light knows that it doesn’t take much for the iPhone’s camera to completely lose the high or low end of the spectrum.

I run into this limitation all the time when I’m out on a hike and come across a vista I want to capture. If there’s any kind of sun at all, I’m forced to choose between either exposing for the foreground and losing the sky in a big wash of white, or exposing for the sky and losing the foreground in darkness. Either way, there’s pretty much zero chance of accurately capturing the scene. Unless, of course, I resort to HDR.

If you’re not familiar with the process of HDR imaging, the overall concept is really pretty simple. By merging multiple images, each individually exposed for a different point in the range of luminances from dark to light, we can form a single image that is able to display the full range. Using my example above, that means I can take one photo that exposes for the foreground and another that exposes for the sky and then combine them together to get a single image that more accurately displays the full range of light in the scene.

Because the iPhone’s “Tap to focus” feature also adjusts for exposure and white balance, setting up for HDR processing is dead simple. Obviously, it would be better if we could control exposure independently, but we have to work with what we’ve got. Simply pick two areas of the scene with the most contrast, then tap and capture an image exposed for each in turn. Be sure to keep the phone as steady as you can when taking the two images, so they will align properly when processing. Once you’ve got both images, there are a number of options for actually creating the final HDR image.

If you’ve got a copy of Photoshop CS5 (s adbe), it has HDR merging and toning built right in. From the File menu, choose Automate > Merge to HDR Pro, then play with the myriad of sliders you see on the right hand side to get the look you want. You can keep the image photorealistic, or push it all the way to something entirely surreal depending how artistic you feel. There’s also a super useful “remove ghosts” option in case you shifted the camera slightly while taking the individual photos.

If you prefer to do all the processing on the phone itself, there are a couple apps available. The best of the bunch is Pro HDR. Like before, you need two contrasting photos (unfortunately you’re limited to only two). You can use images already on the phone or take new photos within the app itself. After the images are merged, you can then adjust the brightness, contrast, saturation, and warmth to fine tune the image to your liking.

While all of this does extend the camera’s functionality a bit, it’s still not perfect. In the end, it’s just a 5-megapixel camera, and it’s never going to be able to match the kind of images one can get from a prosumer-grade DSLR. Constraints drive creativity though and it’s the wealth of iPhoneTography apps available in the App Store — and the users’ own imagination — that really let the iPhone camera carve out a niche for itself. I’d probably be better served by taking a more complete camera with me on my walks, but I use the iPhone for so many other things that it’s hard to argue against a multi-use item with such a great function-to-weight ratio.