Yesterday I was in Jackson Square in the French Quarter in New Orleans. It was a bright sunny day, but because of the trees in the park there were lots of areas of shadows. I thought that this would be a good opportunity to try out the HDR features of the iPhone 4 and iOS 4.
HDR is not right for every photograph, but it can sometimes make a big difference and result in much nicer pictures. Here are two pictures (original on the left, HDR version on the right) for which I first tapped on the St. Louis Cathedral to make that the focus of the picture. (In all pictures in this post, you can click on the picture to see the full size version.) The HDR version brings out more detail in the tree and the rest of the picture. On the other hand, the HDR version also reduces the shadows on the surface of the cathedral, which makes the surface of the church more striking in the non-HDR version:
Here is another example where I feel that the HDR version is better than the regular version. There is more detail and a wider range of color. In all of these examples, you can also see one side effect of HDR in iOS 4; it tends to make the picture as a whole lighter.
Because HDR works by taking three pictures in a row, HDR can create problems when there is movement during the three pictures. For example, in the next set, you can see the movement of a person (especially around his head) in the HDR version on the right.
Similarly, you need to be careful to hold the camera very steady. I didn't do so when I took this picture of a statue of Andrew Jackson, and here is the HDR result. I suppose that one could argue that there is something to be said for the illusion that the horse is moving, but that wasn't what I was trying to do.
The built-in HDR function of iOS 4 is fast and nice, but you don't have any control over the process. You can get more control with the app Pro HDR ($1.99). I purchased that app shortly before Apple had announced that HDR would be built-in to iOS 4, and after I learned that HDR would be a part of iOS 4, my first thought was that I had wasted my money on the app. To the contrary, my experience is that you can often get better results with Pro HDR.
When you launch Pro HDR, you are given both an automatic and a manual HDR option:
If you choose automatic, once you tap your screen to start the process you will watch the screen go from very light to very dark as the app analyzes the image with different exposure settings. Then the app will take one light picture and one dark picture. The app tells you it is doing so and you can hear the sound of a picture being taken each time, so unlike the iOS 4 version of the Camera app, you actually know when the pictures are being taken. Then the app analyzes the two pictures, and then you are given the result with the option to further refine a number of settings: brightness, contrast, saturation, warmth and tint.
Although the automatic setting can work well, I prefer the manual setting. In this mode, the app asks you to first select somewhere on the image that is bright, then to select somewhere on the image that is dark. After those two taps, the app then takes two pictures to get the best exposure for those two areas of the image, and then goes through the same steps noted above.
The process of taking an HDR picture with Pro HDR takes more time than using iOS 4. However, the end result is sometimes (although not always) a much better HDR picture than what you get with iOS 4. For example, here is a set of pictures taken using the normal Camera app (original on left, iOS 4 HDR on the right):
Here is a version using Pro HDR, which I consider a vast improvement over the iOS 4 HDR picture:
I really love the iPhone 4 camera. The picture quality often rivals point-and-shoot cameras, and thus you can just leave the "real" camera at home. And with the iOS 4 HDR function, the pictures can be better than what you get with point-and-shoot. With Pro HDR, you need to take a little more time taking each photograph, but the end result can be really amazing. I'll end with the following non-HDR picture taken across the street from Jackson Square in a spot where millions of tourists and locals have taken pictures. Very expensive cameras have surely resulted in better versions of this picture, but the iPhone 4 holds its own:
Click here for Pro HDR ($1.99): 
