13 Oct 2016

RAW Has Significant Drawbacks on Mobile

When photographers want more flexibility than JPEG, they generally choose RAW. The iPhone 6s was the first iPhone to support RAW. Android started supporting RAW earlier, since Lollipop.

But RAW photos on have significant drawbacks on mobile. Using RAW turns off many enhancements the device or camera app does does that you can't replicate in post-processing.

The first enhancement is HDR, which requires multiple photos. A RAW file can store only one.

You can work around that by storing multiple files, but those are a pain to track. I sometimes mix them up, especially if I took multiple shots of the same scene, as protection against shake, or from slightly different angles. Later on, I may get confused which set of photos should be fused to HDR. So, RAW HDR is a bit of a nuisance. Whereas, with JPEG, the camera app saves only the final HDR result, so you don't have to track multiple files.

RAW is needed more often on mobile devices than on high-end cameras like mirrorless cameras or SLRs, since mobile devices have less dynamic range.

The second drawback of RAW is that using it turns off multi-frame noise-reduction, where iOS takes several photos and combines data from them to reduce noise. The same technique is available on Android via third-party camera apps, if I remember correctly.

Third, iOS uses this multi-frame technique technique to do more than reduce noise. For example, if you have a group of people where different people are moving, and therefore blurry, at different times, Apple says iOS can take a bunch of photos and extract each person's face from the frame in which it was clear.

Fourth is the iPhone 7 Plus, which combines image data from both cameras to produce a better-quality photo:

RAW photos can't combine data from the wide and telephoto lenses.

Fifth, the Huawei P9 has two sensors, but with the same focal length. One is a color sensor while the other is a monochrome. Getting rid of the color filter array triples the light falling on the sensor, resulting in photos that are less noisy and are sharper. The phone combines this photo with the color photo from the other sensor, for the best of both worlds. This technique again doesn't work with RAW.

If you take RAW photos on a mobile device, you're turning off all these enhancements, which you can't do later in post-processing. RAW on mobile devices has all these disadvantages. Don't always take RAW photos, on mobile devices, like you may be used to on a mirrorless camera.

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