Index: /trunk/psLib/src/math/psPolynomialUtils.c
===================================================================
--- /trunk/psLib/src/math/psPolynomialUtils.c	(revision 7466)
+++ /trunk/psLib/src/math/psPolynomialUtils.c	(revision 7467)
@@ -124,9 +124,10 @@
 {
     PS_ASSERT_IMAGE_NON_NULL(image, NULL);
-    PS_ASSERT_INT_WITHIN_RANGE(x, 0, image->numCols - 1, NULL);
-    PS_ASSERT_INT_WITHIN_RANGE(y, 0, image->numRows - 1, NULL);
 
     long ix = x - image->col0;
     long iy = y - image->row0;
+
+    PS_ASSERT_INT_WITHIN_RANGE(ix, 1, image->numCols - 1, NULL);
+    PS_ASSERT_INT_WITHIN_RANGE(iy, 1, image->numRows - 1, NULL);
 
     psF32 *Fm = &image->data.F32[iy - 1][ix];