Toralf Lund wrote:
And no matter which way you look at it, you cannot extend the bandwidth. Which is why I say interpolation doesn't change the resolution.
Depends what your definition for resolution is. If you define it as the size of the smallest details that can be recorded, then you're right. But the film guys would say that you're talking about resolving power not resolution. If you define it as number of pixels (per inch) then it doesn't make sense.
Mathematically, interpolation is the estimation of a function based on certain known function values.
Yes I know, what we have here again is a problem of language abuse.
What is important to know is that the ideal reconstruction (or "interpolation" that guesses 100% right) is done with a sum of weighted sinc functions (something like a sum of p*sin(x)/x terms, one per each pixel in the image).
Since this takes ages to compute, you use approximations of this functions in the form of "bicubic" "bilinear" or "nearest". They compute much faster but are not perfect i.e. they give some slightly wrong guesses (artifacts).
Now if you explore some really proffesional image processing software (like the kind used for satellite imagery), you'll notice that the "sinc" method is available too. Recommended of course to be used only with parallel computing clusters.
cheers !
