Notes on output kernels

diff --git a/pixman/refactor b/pixman/refactor
index f7ac86d..7a7290e 100644 (file)
--- a/pixman/refactor
+++ b/pixman/refactor
@@ -276,6 +276,25 @@ Possibly interesting additions:
          will need to deal with the fact that the resampling kernel
          will not necessarily be pixel aligned.
 
+         "Output kernels"
+
+         One could imagine doing the resampling after compositing,
+         ie., for each destination pixel sample each source image 16
+         times, then composite those subpixels individually, then
+         finally apply a kernel.
+
+         However, this is effectively the same as full screen
+         antialiasing, which is a simpler way to think about it. So
+         resampling kernels may make sense for individual images, but
+         not as a post-compositing step.
+         
+         Fullscreen AA is inefficient without chained compositing
+         though. Consider an (image scaled up to oversample size IN
+         some polygon) scaled down to screen size. With the current
+         implementation, there will be a huge temporary. With chained
+         compositing, the whole thing ends up being equivalent to the
+         output kernel from above.
+
        - Color space conversion
 
          The complete model here is that each surface has a color