Aliet wrote:

> I noticed on some of the finished pictures some sort of pattern like
> artifacts and pixels with offending colors whenever there was
> transparent gray or black over white o clear backgrounds, I also
> noticed that these were downscaled using Sinc(Lanczos3)
> interpolation. I've been conducting some tests to compare Cubic and
> Sinc interpolations on my pictures, I know Sinc is the theoretical
> optimum but I needed to see in practice if the difference was
> noticeable enough and if so always use it

There is no perfect resizing filter.  All filters will cause one of two
kinds of problems, either ringing (windowed sinc filters like Lanczos)
or blurring (cubic).  You choose between them on a case-by-case basis
depending on whether you want to preserve detail (Lanczos) or minimize
artifacts (cubic).

Sinc is only ideal in an ideal world.  In the real world, resizing
filters must have finite extent, and RGB levels are typically limited to
8 bits of precision.

- Ernie                        

Gimp-user mailing list

Reply via email to