Antialiasing, part 3

Sunlit wet asphalt aside, most pictures I make with cameras lacking antialiasing filters look just fine with no special post processing. That doesn’t mean that there’s no aliasing going on; it just means that the artifacts thus produced look fairly realistic and aren’t objectionable.

There are two eminently defensible but mutually exclusive perspectives on whether to use an antialiasing filter at capture time.

1. You’ve got to use an antialiasing filter, because once the aliased information is captured, no post processing in the world can sort out what’s aliased and what’s not, and thus the image can never be corrected.
2. You don’t want an antialiasing filter, because it costs you sharpness. If you get visible aliasing, you can make the image look good with a little post processing.

The counterarguments are as follows:

1. We’re not doing forensics here. It’s not important that the image be a mathematically accurate view of the world; the main thing is that it looks realistic.
2. The algorithms that reduce aliasing artifacts blur detail and desaturate fine structures; you can’t just apply them to every part of every image. I don’t have the time or energy to go through every photograph looking for artifacts and fixing them; let the camera get rid of them.

There’s a British expression “horses for courses” that translates to something like “what’s best depends on the situation.” That applies here. If you’re a journalist, or a wedding photographer, or anyone else producing pictures in bulk with little or no editing, you want the antialiasing filter. If you’re an artist looking for one or two great images a month, or a commercial photographer looking for one or two great images a day, and are willing to spend the time going over your work with a fine-tooth comb finding and fixing artifacts, then you’re probably better off without it.

If you buy that line of reasoning, then maybe you’ll like my speculation as to why most 35mm-sized DSLRs have antialiasing filters and most medium format DSLRs don’t: most of the people buying the bigger cameras are using them in situations where they are producing a few very high-quality images, and they’re willing to suffer the pain of finding and correcting the artifacts.

Note that I keep emphasizing finding the artifacts. If you’re going for the very best quality and treating every picture like it’s precious, you’ve raised the stakes. You sure don’t want to be standing in a gallery with your pictures on the wall and have someone spot something that’s just not right, or turn in the double page spread for which you’re charging many thousands, and have the art director see a problem.

Next time: what the future might hold.