What are these striped artifacts in these photos?

Question

I was at a concert and some of the pictures I took had these blue and red or black stripe artifacts, is there a name for these? Would I be able to make a similar or same effect if I desired or are these uncontrollable? The pictures were taken on an iPhone 8.

Answer 1

A concert means rapidly changing, extreme light conditions. It looks like the conditions changed between metering and taking the picture. E.g. in the 2nd picture, the pink light came on and blew out the darker areas. I will base my answer on that assumption.

The phone then tries to recover by extreme post-processing. We cannot really know it's algorithms, but a few bits of color data need to cover the whole dynamic range. We get a few shades of green instead of hundreds. You can see that best in the "rings" around the green lights in the 1st picture, then outward several darker rings until black is reached.

The blue channel is probably not as much overexposed as the green one, so we can stretch blue and green differently - and get some shades of cyan in the process. You can get similar results with extreme highlight or shadow compression in RawTherapee or other programs.

The purple and blue lines appear at the border to the region illuminated by the blue lights. Again, there are only a few bits effectively available for each color, so you can't get the smooth transition you would rather like.

The fog is complicating things. There might have been more or less fog in a specific area, throwing shadows or reflecting more light.

Answer 2

The image defect can be described as posterization and results from aggressive colour correction which most modern cameras apply to obtain normal colours in common use case scenarios. You might get same problem even with large expensive cameras even though to a lesser extent. Modern cameras are tuned to produce good colour in common use cases (sunlight, incadescent lighting, natural dies) but will fail miserably when exposed to mix of saturated colours and gradients.

However, this defect can be easily dealt or at least significantly mitigated using negative exposure correction, highlight recovery, saturation adjustment (you can probably do that even in your smartphone) and tone curves. You might try different smartphone camera software and you might try taking raw photos and developing them yourself, that would stretch your abilities to deal with this quite a lot.