diff --git a/panda/src/grutil/pfmVizzer.cxx b/panda/src/grutil/pfmVizzer.cxx
index f068311422..c3fc150816 100644
--- a/panda/src/grutil/pfmVizzer.cxx
+++ b/panda/src/grutil/pfmVizzer.cxx
@@ -935,20 +935,24 @@ add_data(const PfmVizzer &vizzer, GeomVertexWriter &vwriter, int xi, int yi, boo
   case CT_normal3:
     {
       // Calculate the normal based on two neighboring vertices.
+      bool flip = reverse_normals;
+
       LPoint3f v[3];
       v[0] = pfm.get_point(xi, yi);
-      if (xi + 1 < pfm.get_x_size()) {
+      v[1] = v[0];
+      v[2] = v[0];
+      if (pfm.has_point(xi + 1, yi)) {
         v[1] = pfm.get_point(xi + 1, yi);
-      } else {
-        v[1] = v[0];
-        v[0] = pfm.get_point(xi - 1, yi);
+      } else if (pfm.has_point(xi - 1, yi)) {
+        v[1] = pfm.get_point(xi - 1, yi);
+        flip = !flip;
       }
                 
-      if (yi + 1 < pfm.get_y_size()) {
+      if (pfm.has_point(xi, yi + 1)) {
         v[2] = pfm.get_point(xi, yi + 1);
-      } else {
-        v[2] = v[0];
-        v[0] = pfm.get_point(xi, yi - 1);
+      } else if (pfm.has_point(xi, yi - 1)) {
+        v[2] = pfm.get_point(xi, yi - 1);
+        flip = !flip;
       }
                 
       LVector3f n = LVector3f::zero();
@@ -961,7 +965,7 @@ add_data(const PfmVizzer &vizzer, GeomVertexWriter &vwriter, int xi, int yi, boo
       }
       n.normalize();
       nassertr(!n.is_nan(), false);
-      if (reverse_normals) {
+      if (flip) {
         n = -n;
       }
       if (!transform_vector(n)) {
diff --git a/panda/src/pnmimage/config_pnmimage.cxx b/panda/src/pnmimage/config_pnmimage.cxx
index 6edc7ed71a..c5bf782fe9 100644
--- a/panda/src/pnmimage/config_pnmimage.cxx
+++ b/panda/src/pnmimage/config_pnmimage.cxx
@@ -36,6 +36,20 @@ ConfigVariableBool pfm_reverse_dimensions
           "backwards, in the form height width instead of width height, "
           "on input.  Does not affect output, which is always written width height."));
 
+ConfigVariableBool pfm_resize_gaussian
+("pfm-resize-gaussian", true,
+ PRC_DESC("Specify true to implement PfmFile::resize() with a higher-quality "
+          "Gaussian filter, or false to implement it with a faster box "
+          "filter.  This just controls the behavior of resize(); you can "
+          "always call box_filter() or gaussian_filter() explicitly."));
+
+ConfigVariableDouble pfm_resize_radius
+("pfm-resize-radius", 1.0,
+ PRC_DESC("Specify the default filter radius for PfmFile::resize().  "
+          "This just controls the behavior of resize(); you can "
+          "always call box_filter() or gaussian_filter() explicitly with "
+          "a specific radius."));
+
 ////////////////////////////////////////////////////////////////////
 //     Function: init_libpnmimage
 //  Description: Initializes the library.  This must be called at
diff --git a/panda/src/pnmimage/config_pnmimage.h b/panda/src/pnmimage/config_pnmimage.h
index 6eecae1203..d9badbf2b4 100644
--- a/panda/src/pnmimage/config_pnmimage.h
+++ b/panda/src/pnmimage/config_pnmimage.h
@@ -17,13 +17,15 @@
 
 #include "pandabase.h"
 #include "notifyCategoryProxy.h"
-#include "configVariableInt.h"
 #include "configVariableBool.h"
+#include "configVariableDouble.h"
 
 NotifyCategoryDecl(pnmimage, EXPCL_PANDA_PNMIMAGE, EXPTP_PANDA_PNMIMAGE);
 
 extern ConfigVariableBool pfm_force_littleendian;
 extern ConfigVariableBool pfm_reverse_dimensions;
+extern ConfigVariableBool pfm_resize_gaussian;
+extern ConfigVariableDouble pfm_resize_radius;
 
 extern EXPCL_PANDA_PNMIMAGE void init_libpnmimage();
 
diff --git a/panda/src/pnmimage/pfmFile.cxx b/panda/src/pnmimage/pfmFile.cxx
index ff9ddee2cb..17c147c458 100644
--- a/panda/src/pnmimage/pfmFile.cxx
+++ b/panda/src/pnmimage/pfmFile.cxx
@@ -839,13 +839,17 @@ resize(int new_x_size, int new_y_size) {
   PfmFile result;
   result.clear(new_x_size, new_y_size, _num_channels);
 
-  if (new_x_size < _x_size && new_y_size < _y_size) {
-    // If we're downscaling, we can use quick_filter, which is faster.
-    result.quick_filter_from(*this);
-
+  if (pfm_resize_gaussian) {
+    result.gaussian_filter_from(pfm_resize_radius, *this);
   } else {
-    // Otherwise, we should use box_filter(), which is more general.
-    result.box_filter_from(0.5, *this);
+    if (new_x_size <= _x_size && new_y_size <= _y_size) {
+      // If we're downscaling, we can use quick_filter, which is faster.
+      result.quick_filter_from(*this);
+      
+    } else {
+      // Otherwise, we should use box_filter(), which is more general.
+      result.box_filter_from(pfm_resize_radius, *this);
+    }
   }
 
   _table.swap(result._table);
diff --git a/panda/src/pnmimage/pnm-image-filter-sparse-core.cxx b/panda/src/pnmimage/pnm-image-filter-sparse-core.cxx
index 5631979759..bed23f3e2a 100755
--- a/panda/src/pnmimage/pnm-image-filter-sparse-core.cxx
+++ b/panda/src/pnmimage/pnm-image-filter-sparse-core.cxx
@@ -53,9 +53,9 @@ FUNCTION_NAME(IMAGETYPE &dest, const IMAGETYPE &source,
   double filter_width;
 
   make_filter(scale, width, filter, filter_width);
-  memset(temp_source_weight, 0, source.ASIZE() * sizeof(StoreType));
 
   for (b = 0; b < source.BSIZE(); b++) {
+    memset(temp_source_weight, 0, source.ASIZE() * sizeof(StoreType));
     for (a = 0; a < source.ASIZE(); a++) {
       if (source.HASVAL(a, b)) {
         temp_source[a] = (StoreType)(source_max * source.GETVAL(a, b, channel));