One of my favorite features of the recently released iOS 4.1 update is HDR photos on the iPhone 4. HDR stands for High Dynamic Range, and Wikipedia explains it as such:
[...]high dynamic range imaging (HDRI or just HDR) is a set of techniques that allow a greater dynamic range of luminance between the lightest and darkest areas of an image than standard digital imaging techniques or photographic methods. This wider dynamic range allows HDR images to more accurately represent the wide range of intensity levels found in real scenes, ranging from direct sunlight to faint starlight.
Basically, if a beautiful blue sky is blown out to white in a normally exposed photograph, an HDR of the same scene, composed of three shots at different exposures, will more than likely show the sky along with the rest of the scene.
As an example, examine the differences in this photo I took between the normal, single shot exposure on top and the three-exposure HDR of the same scene below.
Normally, it is a time-consuming process to create HDR photos, at least for beginners. I would throw myself in this category. But the iPhone 4 is automatically taking care of all the messy stuff. Just click the HDR On toggle in the Camera app, tap to focus, then take the shot. The iPhone 4 will automatically take three exposures, and then mesh them together into an HDR. The is a preference in the Camera section of Settings.app on your iPhone to save the original exposure. It is on by default.
The camera on the iPhone 4 was already one of my favorite features, but built-in, easy as pie HDR has added just that much more value. If you have an iPhone 4 and haven’t played with HDR yet, shame on you.