[gegl/samplers] wrong sign

[Nicolas Robidoux <nrobidoux src gnome org>]

commit 93ab39035e0313f3a532f14714037b0b37e97f1b
Author: Nicolas Robidoux <nicolas robidoux gmail com>
Date:   Wed Jun 22 20:14:25 2011 -0400

    wrong sign

 gegl/buffer/gegl-sampler-lohalo.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/gegl/buffer/gegl-sampler-lohalo.c b/gegl/buffer/gegl-sampler-lohalo.c
index d08af19..05c61a1 100644
--- a/gegl/buffer/gegl-sampler-lohalo.c
+++ b/gegl/buffer/gegl-sampler-lohalo.c
@@ -2143,11 +2143,11 @@ gegl_sampler_lohalo_get (      GeglSampler* restrict self,
 	     * units":
 	     */
 	    const gfloat x_1 =
-	      ( (gfloat) ( ix_0 - 2 * ix_1 ) + (gfloat) 0.5 + x_0 )
+	      ( (gfloat) ( ix_0 - 2 * ix_1 ) + x_0 + (gfloat) -0.5 )
 	      /
 	      (gfloat) 2.0;
 	    const gfloat y_1 =
-	      ( (gfloat) ( iy_0 - 2 * iy_1 ) + (gfloat) 0.5 + y_0 )
+	      ( (gfloat) ( iy_0 - 2 * iy_1 ) + y_0 + (gfloat) -0.5 )
 	      /
 	      (gfloat) 2.0;