Midweek mobile 2

A mobile camera is not a good camera in ways that photographers were used to thinking of. The lens is a toy. Four centwp-admin/wp-admin/wp-admin/uries worth of lens technology have been junked by two related developments. The most important? That about 95% of the world looks at photos on tiny screens when distributing likes. So you don’t need the sharpness that photographers of old wanted; sell megapixels instead. That translates to about 10 Mbytes for the featured photo when my camera saves it. I know from experience that even on my large screen I can easily compress it down to about 200 kbytes and most people would not be able to tell the difference. That means I can retain only 2% of what is recorded. And on my phone I could easily throw away another 90% of the information (retain just 0.2% of the original) and no one would be able to tell. Then why so many megapixels? Because when you start from a large format photo and compress it down to a small screen, everything looks sharp.

You might remember that when you last changed your phone the picture quality changed a lot. Is that all due to more pixels? In a big part, yes. I dropped my old phone too often and was forced to change it quicker than I normally do. In three years the number of pixels in photo from a less-than-mid-range phone had gone up from around 10 million to about 65 million. Now look at the featured photo. The architectural details look sharp, considering that the subject is more than 300 meters away, and it was taken from a car that was making a sharp turn at a reasonable speed. But look at the near-full size blow-up in the photo above. You can see that at this zoom, details are pretty blurred. I have gained the clarity of the featured photo purely by not looking at it at full scale.

But that’s not the only change when you get a new phone. You also get a different AI translating the sensor output into an image. And this technology, which is a guess at what is being seen, is improving rapidly. As a result, the distortions of a bad lens can still be interpreted better, and result in a reasonable image. Note that this phone can remove digital noise much better than a five years-old phone would have done. The darker areas of the photo are much more clean (the detailed view above has been cropped out in the featured photo). Also, notice that the new generation AI deals with non-white faces better than before, getting an impressive image for the man walking towards the camera. This improvement is a response to accusations of biased training of AI.

But another detail is technically very impressive. Notice the level of detail? I can see very clearly that he is not wearing a mask. This resolution is better than a fundamental limitation which is imposed on lenses due to the wave nature of light (something called Rayleigh’s resolution limit). This computational super-resolution is a statistical trick which improves the image by making a guess about the nature of the ambient light. The down side of all this AI? This much of computation has a carbon cost. When I use my phone only for communication, the batteries last three and a half days. Street photography can drain the charge in a few hours.

Phone photography changes our expectation of the interaction of camera hardware and image so dramatically that it is worth rethinking what photography means. I intend to explore this a bit in this series.

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