[cameldrv]

I don't think it's just subjective in this case. The theoretical signal processing approach assumes that the signal is band-limited to frequencies less than two pixels wide, and it's not. There are lots of sharp edges that have higher frequency components than that.

Another way of looking it, more along the lines that you're talking about, is that it depends on your error model. The traditional way of measuring error is RMS pointwise in pixels. Doing some sort of interpolation on pixels gives a pretty good result for that. However, another way to look at it is that it may be better to have a positional error, i.e. a particular color or intensity level is in the wrong spot, than to have an intensity/color error, i.e. you have a pixel that has an intensity/color that's not present in the source signal.

This same basic issue was the basis of a big divide in font rendering for many years, where the Mac would render fonts with the exact geometry of the letters, but then anti-aliased, while Windows would use font hinting to make the shape snap to the pixel grid. Personally I thought that the Windows approach was a lot easier to read on a screen, but the Mac approach had the advantage that the geometry of the text would be exactly the same in print as it was on the screen, back when print was something that was important, especially for Mac users.