[Gimp-user] scaling

[Andrew]

David Gowers wrote:
> On 9/24/07, Andrew <ald2 at arrakis.es> wrote:
>   
>> Hi,
>>
>> How does 'sinc (lanczos3)' interpolation compare with the others for
>> quality?
>>     
>
> For upscaling, it's roughly like sharpening the image and scaling it
> up with Linear interpolation. That is not the method, just how the
> result looks.
> Arguably this counters the typical blurring incurred by upscaling.
> Personally I've always preferred manual sharpening to using Lanczos.
>
> Lanczos downscaling is interesting, but you won't find that in your
> copy of gimp -- it's still being worked on.
>
>   
The Wikipedia article certainly was over my head.

 From what I read on the Gimp bug page lanczos scaling is not yet 
perfect. (But then what is?)

I have to upscale images from 16M to 48M and it seems the client takes 
them apart and looks at them through a microscope and rejects them if 
there are signs of sharpening or interpolation artefacts.

So far as I can see, my Gimp (2.4.0-rc2) does have lanczos downscaling


Thanks for your help,

Andrew