[Gegl-developer] Proposition : GeglInterpolator

[Øyvind Kolås]

On 10/17/06, geert.jordaens at telenet.be <geert.jordaens at telenet.be> wrote:
> >If you scale a image to 10% of the original size using cubic, you have
> >a situation where the data for each destination pixel is taken from a
> >region of 4x4pixel, whilst it should at least be taken from a region
> >of 10x10pixels, 84% of the image data is thrown away.
>
> OK, the handling of scaling down is not yet in the proposition
>
> Could we not just add the scale factor to the API ?

The scale factor is not enough, if we scale it to 10% horizontally and
70% vertically (or add some kind of rotation as well). A fixed scale
factor would no longer be correct. Doing a reverse transform of the
"corners" of the destination pixel would give us all the information
we need, and work for perspective transforms as well, hence the method
I suggested.

/Øyvind K.

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