Re: why is quartz still interpolating ??
Re: why is quartz still interpolating ??
- Subject: Re: why is quartz still interpolating ??
- From: Robert Clair <email@hidden>
- Date: Tue, 27 Apr 2004 08:32:16 -0400
Thanks, Dietmar, for the extended discussion on how the rendering
accounts for pixel boundaries.
But how does this relate to compositing an arbitrarily scaled and
rotated image ?
The simple (non-fixed up for efficiency, textbook) way of doing this
is to box the transformed src image bounds and then for each dst
pixel in that box, transform its coordinates back to the src image space
and see what color is in the src image under that point.
Note that this will never give you a color that is not in the src image
and that observation is independent of whether you consider a pixel's
coordinates
to be at the center or at the corner.
Interpolation would involve taking several samples from different
locations in the src pixel box, applying the procedure and averaging.
So my question remains: why, when asked not to interpolate or
anti-alias,
is Quartz still interpolating? Since "none" is the cheapest thing to
do, why
won't it do it? (I've tried speaking very sternly to it...)
Bob Clair
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