[gegl/samplers] comments

[Nicolas Robidoux <nrobidoux src gnome org>]

commit 2acbb8cd5ccb6d621b8becc140a4be45434384af
Author: Nicolas Robidoux <nicolas robidoux gmail com>
Date:   Thu Jun 30 08:25:50 2011 -0400

    comments

 gegl/buffer/gegl-sampler-lohalo.c |   23 +++++++++++++++++------
 1 files changed, 17 insertions(+), 6 deletions(-)
---
diff --git a/gegl/buffer/gegl-sampler-lohalo.c b/gegl/buffer/gegl-sampler-lohalo.c
index cec7293..4a2cfd6 100644
--- a/gegl/buffer/gegl-sampler-lohalo.c
+++ b/gegl/buffer/gegl-sampler-lohalo.c
@@ -40,6 +40,16 @@
  */
 
 /*
+ * Reference:
+ *
+ * Nohalo subdivision (with bilinear instead of LBB "finish") is
+ * documented in Robidoux, N., Gong, M., Cupitt, J., Turcotte, A., and
+ * Martinez, K.  CPU, SMP and GPU implementations of Nohalo level 1, a
+ * fast co-convex antialiasing image resampler.  In Proceedings of
+ * C3S2E. 2009, 185-195.
+ */
+
+/*
  * Credits and thanks:
  *
  * Jacobian adaptive resampling was developed by N. Robidoux and
@@ -2333,12 +2343,13 @@ gegl_sampler_lohalo_get (      GeglSampler* restrict self,
                  * Update using mipmap level 1 values.
                  *
                  * Possible future improvement: When the ellipse is
-                 * slanted, one could avoid many operations using
-                 * Anthony Thyssen's formulas for the bounding
-                 * parallelogram with horizontal top and bottom. When
-                 * both the magnification factors are the same, or
-                 * when there is no rotation, using these formulas
-                 * makes no difference.
+                 * slanted, one could avoid many pixel value loads and
+                 * operations with Anthony Thyssen's formulas for the
+                 * ellipse bounding parallelogram with horizontal top
+                 * and bottom. When both the magnification factors are
+                 * the same, or when there is no rotation, using these
+                 * formulas makes no difference. Reference:
+                 * ImageMagick resample.c.
                  */
                 {
                   gint i;