Sunday, July 13, 2008

G9: Face Detection Focusing

In previous posts, the various ways of focusing the G9 along with the concept of hyperfocal distance were presented. Along with the various ways of focusing the G9, I discovered a few perculiarities – to me anyway – both indoors and outdoors.

Up to this time, I’ve only briefly mentioned face detection focusing and pointed out that the G9 switches to AiAf focus mode if no faces are detected. It’s time to delve into face detection in more detail.

Like more than a few photographers, when I first heard about face detection, I laughed. How could it be effective? Who would need it? Well, it turns out that face detection has evolved rapidly, is quite effective and most people benefit from face detection focusing. For example, in my family, like most families, we take a lot of snapshots. We set a snapshot camera on full auto, pass it around and tell young and old to take a few shots. The G9 can do all this and does it well -- especially in face detection mode.

In the past several months, I’ve been a snapshooter at several parties and family get-togethers. I tried face detection focusing in desperation and, to my surprise, it worked. In fact, I’ve switched our snapshot camera, a Canon SD800, to face detection.

I don’t know how face detection focusing works. A computer program uses pattern recognition algorithms based on the shape of typical faces, eye spacing, color, hair, etc. to select a subject and then set focus on that subject. The Canon G9 is sometimes said to detect up to nine faces but the instruction manual says that up to three frames display where the G9 detects faces. When the G9 is in face detection mode, the LCD display shows the detection frames lock onto a face. Fascinating.

Natually, I attempted to trick the face detection algorithm and set up this award winning composition. Hey, aren’t these faces? However, the G9 said that no faces were detected (Elmo and friends were insulted) until the portrait was included. The G9 immediately locked onto the portrait as a “face” onless the portrait was placed near an edge of the composition. Interesting. This picture was taken in manual exposure mode without flash at f3.2, 1/30 second and ISO 800 in face detection mode.

Face detection focusing is said to include enhancements to improve exposure, especially when using flash. I hope this is true but I didn’t notice any differences during the tests of this scene. I also tried a few self portraits using the 10 second delay but, again, did not notice any difference in flash exposure with or without face detection. In my other uses of face detection, I don’t have comparative images.

I don’t doubt that face detection improves flash exposure but I don’t have proof at this point. I’m late coming to face detection but expect to be using it more frequently in the future. Stay tuned, but in the meantime, try face detection.

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