First Test Drive of HDR Photos in iPhone 4

With the release of iOS 4.1, Apple added high dynamic range support (HDR photos) to the built-in camera on the iPhone.  So what is HDR?  In Steve Jobs’ own words, “when you take a photo (with HDR turned on), it actually takes 3 photos in rapid succession.  It takes 1 normal exposure what it thinks is the appropriate exposure, 1 that’s under exposed, and 1 that’s over exposed.  And it combines these 3 photos with some pretty sophisticated algorithm to produce a HDR photo”.  The photos below are examples from Apple’s 9/1 product launch that showcases the potential of HDR:

Over the weekend, I took my family to a local amusement park and decided to take some pictures with HDR enabled.  Unfortunately, I was unable to match the quality of Apple’s photos via HDR.  I took over 20 pictures with HDR enabled.  In reviewing the results in iPhoto, I’m only able to identify a couple instances where HDR provided enhancement over the normal exposure.  Below are some side-by-side comparisons, with the normal photo on the left (1st) and the HDR photo on the right (2nd).

In the 1st set of photos, the improvement is very subtle in the HDR version.  It’s barely noticeable, the removal of shadows from the foreground and the over exposure correction of the white color on the side of the cart. Upon closer inspection (click to view in full size), you will find a slight shadow casted around the human subjects in the HDR photo, either because I moved the camera or the subjects moved between frames.

In the 2nd set of photos, the improvement is more noticeable in the HDR version.  The over exposed background gets corrected in the yellow booth in the upper left corner and the trees in the upper right corner.  But the subject in the foreground remains dark.  Upon closer inspection, you will find the background human subjects to be a bit distorted in the HDR photo, most likely because they moved between frames.

The first two sets of photo were taken where the subject is relatively still.  I took many pictures where the subject was in full motion, and understandably those turned out poorly in HDR:

This was my first test drive of HDR in iOS 4.  Since it didn’t exact come with an user manual, I’m learning from my own experience.  I could simply enble HDR for all photos, but if the yield of good HDR photos from my weekend experience is an indication of the expected norm, I will waste a lot of time deleting HDR photos from my album.

From this experience, I have devised some simple rules on when to use and when not to use HDR:

  • Don’t use HDR to take pictures that involve any form of motion
  • Use HDR when taking landscape pictures with or without human subjects
  • Use HDR when taking pictures with drastic lighting variation between foreground and background

Hopefully by following my own guidance, I will be able to take better pictures by utilizing HDR under selective conditions.

Note:  Th Apple photos were borrowed from the Sep 1st Apple product launch.  You will find the HDR introduction around the 7 minute mark in this video.


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