Sunlight on pines and grassland, mountains behind. It was a lovely scene which I captured with my phone. The phone used a lens which is 4.7 mm wide and has a fixed aperture f/1.7. It reported an exposure of 1/1043 seconds and an ISO of 100. The sensor on my phone has 4608 x 3456 pixels. This is an aspect ratio of 4:3, which I’ll retain in all the experiments I show here. The original jpeg image the phone gave me had 9248 x 6936 pixels. I compressed the image down to 1250 x 938 pixels in the header photo. It looks rather nice on my phone, and also on my laptop screen. The image has areas of bright illumination and areas of pretty heavy shadow. It also has some sharp colour contrasts. I was interested in how well the images look when I zoom in so that one pixel in the photo shows up as a single pixel on my laptop’s display.
Here is a zoom into brightly lit pine needles. I took a section which had 832 x 624 pixels and reduced it 640 x 480 pixels to show you in this post. All the following images also do exactly the same. You can see lots of digital artifacts. The most noticeable is aliasing: smooth lines and curves appearing jagged in the image. The software has teased out a lot of detail both in shadow and in full light, but the jaggedness makes it look somewhat artificial.
Next I zoomed into a portion of the dappled shadows. This is where your own eyes will play tricks. The camera captured almost nothing in the deepest shadow and the brightest light, but it does quite a good job even in the lighter shadows, apart from the aliasing problem. The best parts of this zoom are the portions where there is a strong contrast of illumination: bright details against dark background. But where a dark portion is seen against a bright background you see strange curves and squiggles. This is due to aliasing.
This zoom shows you a situation where the contrast is in colours, not so much in the level of illumination. Both the sky and the leaves are bright. I’m surprised by the amount of digital noise in the sky, in spite of the ISO being 100. Apart from the aliasing problems, I’m surprised by how soft the pine needles look. This is caused by a problem I’d written about earlier. The image is created by adding together a very large number of separate exposures (a technique called adaptive multiframe image averaging), and the breeze at that height causes the pine needles to move. The softness is due to the motion between different exposures. This is not a problem that a DSLR has; not does it ever have this digital noise in the sky.
I also found incredibly bad digital artifacts in a portion of the photo which looked pretty easy to take. The squiggles in the far slopes are due to aliasing. The strange halo around the shadows is another weird algorithmic effect. The light on the branches is like little bits of paint dabbed on by a bad painter trying to emulate the impressionists. The pine needles are just masses of colour. This zoom makes me think I should never again look at a phone photo blown up to see it pixel for pixel.
If I want sharp details, I should use a DSLR. A phone is what I would use if I wanted a quick snapshot which I would look at only on a little screen which fits in my palm. Conversely, if you want to see the defects in the phone photo, look at these examples on a big screen, not a phone.
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.