[Gimp-developer] patch for scale-region.c

[Alastair M. Robinson]

Hi :)

Geert Jordaens wrote:

> The code is not interpolating rather resampling (supersampling in case 
> of lanczos and bicubic) in the case of scaling down.

OK - perhaps I'm misunderstanding the approach taken here, then.

As with interpolation, the Lanczos/Bicubic functions are being used to 
fit a parametric function to the original discrete samples, yes?

The question is how is this function then used?  Is a single sample 
taken from it for each sample of the scaled-down image, or is the 
function "integrated" over an appropriate interval for each sample?

I'd assumed, perhaps incorrectly, that the former approach was being 
used, and if so, then a simple box-filter should be more accurate; if 
the latter, however, then I'd expect the results to be better than a box 
filter.

All the best,
--
Alastair M. Robinson