Photo Noise Reduction Apps for iPhone
In digital cameras, image noise (grain) is most pronounced in photos taken in low-light conditions without a flash. For such situations, the camera sets high ISO (light sensitivity of the image sensor) and a long exposure. A number of apps are available for the iPhone to reduce the appearance of grain. None of these apps are particularly impressive, especially when compared to specialized PC software. There is a good reason for this: digital noise reduction is a very CPU-intensive process that also requires a large amount of memory.
At full resolution, a photo taken with iPhone 4S may take around ten seconds to be de-noised on a PC. The same process may take over a minute on the iPhone itself. Obviously, such an app would attract only the most patient of users. And so the iPhone apps claiming to “de-noise” grainy photos take a shortcut: they simply blur the image until you cannot see the grain. However, this approach does not just get rid of the noise, but it eliminates much of the good detail in the photo.
Below we will take a quick look at the four best apps for iPhone 4/4S for noise reduction and we will compare the results to those produced on a PC. For consistency, we will use the same photo in all tests. Here’s the original image, resized to 1024px, with a fragment in original resolution showing noise detail.
Among iPhone apps, the best result was achieved with Perfectly Clear. But there is one problem: the original image was 3254 x 2444 px, and Perfectly Clear was only capable of saving it in 2592 x 1946 px. Photogene 2 removed very little noise, but, to its credit, it did not blur the photo either. So it didn’t do much of anything, which in this case was a good thing. Photoshop Express blurred the hell out of our photo. It did remove the noise, but half of the photo was gone along with it. Finally, the Iris did remove a significant amount of noise and did not blur the image too much. However, the end result is not particularly pleasing to the eye. Some odd light pixels were left behind and most shades of gray have disappeared, making the photo look very flat.
So go with Perfectly Clear if you can live with lower resolution. Alternatively, Photogene 2 may be an option: it doesn’t do much but it does it with minimum of damage.
Among PC programs, both Neat Image and Noiseware Pro did a decent job. In this case Noiseware Pro removed more grain, but Neat Image produced a better-looking, sharper image with an acceptable amount of residual noise.