About a month-and-a-half ago, I did something I don’t usually do: I purchased an iPhone camera app for $2.99. I’m certainly no stranger to purchasing apps, but I typically pay little attention to alternative camera apps and I seldom purchase an app — particularly for more than 99¢ — without either a friend’s suggestion or a trial version.
However, something about a mini-review of Cortex Camera convinced me to buy it. What this camera app does is take a quick burst of photos, lasting a few seconds, and then quickly processes those into a single photo. The result is supposed to be a higher quality photo than the built-in camera can provide in lower light settings.
My initial testing was basically positive, but I found it to have fairly limited use. It didn’t support iOS 6’s new low-light functionality, so it really only worked in moderate lighting. In such lighting, Cortex Camera’s results did have more detail and less noise than photos from the built-in camera, but the built-in results were really “good enough”. In true low-light, the built-in camera’s boosted ISO produced much better results. I didn’t delete the app, but wasn’t sure I would be likely to use it.
About a month ago, Cortex Camera received an update with several enhancements. The most notable was support for iOS6’s low-light mode. With this change, the app has become much more useful, as I will now demonstrate.
I took these two photos from the same spot. I had to back up extra so that the trees would block fewer lights, so I zoomed-in when taking both photos, though not by exactly the same amount as you can see. Even in these very-scaled-down versions (click them for full-size), you can see how much smoother the sky is in the Cortex shot.
I did the crops below on the iPad and tried to get them to be the same. One disadvantage of using the iPad is that I can’t look at one crop while I do the other. In retrospect, I could have easily used my iPhone to check the other crop (though I would have had to pause The Daily Show). Even then, the sizes would still have been different due to the slightly different zoom of the original images. I do not think these differences have any effect on the obvious quality win of the Cortex versions.
From these crops you can see that the built-in camera produced very muddy results, presumably due to some aggressive noise correction. Also, there is appreciably more motion blur. I’m not certain, but I think that Cortex uses a shorter exposer and then relies on a certain amount of additive combination of the composite photos to increase the effective exposure. In any event, I’m quite please with the results; well worth $3.
In case it isn’t obvious, this technique — and thus, Cortex Camera — isn’t useful for photos of moving objects.
One other point: some of Cortex Camera’s functionality is iPhone 5 only. On older iPhones, I believe it takes a video rather than multiple photos, so the final resolution is a bit lower (though higher than the video resolution). Also, it’s supposed to support 12.5MP on the iPhone 5, but with that enabled, the app consistently crashes for me.