Tag Archive: camera

Are “Low Light” iPhone Camera Apps Bogus?

There are a number of iPhone camera apps that promise to have superior performance in low light settings by using the iPhone’s accelerometer. The basic idea is very simple and intuitive. To quote from the Night Camera web site:

Due to low light condition, the shutter time is longer, and even small shaking from the tapping of the camera button will make the photo un-usable.

So, we created Night Camera, the app to prevent the blur at the first place. Using the built-in iPhone accelerometer, it automatically shoots the photo when it detects the iPhone being stable, so you have a real chance to get some good photos at night.

Sounds very compelling. Basically image stabilization (or rather image selection based on stability data) on inexpensive hardware.

There is one problem with this, which is that the iPhone according to this post uses a camera module that has a fixed 200ms rolling shutter. This seems very plausible, as most camera modules of cell phone use this technique. There also is plenty of photo evidence that this is the case. With a rolling shutter, the exposure time of the CMOS sensor is fixed. In other words, the claim that the shutter time is longer at night is wrong. Unless I am missing something, the makers of the above application at least don’t understand how the iPhone camera works.

Now it may be that in general the accelerometer could be useful for enhancing image quality by reducing movement. However anecdotal evidence shows no visible improvement, and the above app has only 2.5 start on iTunes.