diff --git a/panda/src/glstuff/glGraphicsStateGuardian_src.cxx b/panda/src/glstuff/glGraphicsStateGuardian_src.cxx
index e357b2c357..9a0a588cdf 100644
--- a/panda/src/glstuff/glGraphicsStateGuardian_src.cxx
+++ b/panda/src/glstuff/glGraphicsStateGuardian_src.cxx
@@ -7586,14 +7586,120 @@ upload_texture_image(CLP(TextureContext) *gtc,
 
   int highest_level = 0;
 
+  bool needs_reload = false;
   if (!gtc->_already_applied ||
       gtc->_uses_mipmaps != uses_mipmaps ||
       gtc->_internal_format != internal_format ||
       gtc->_width != width ||
       gtc->_height != height ||
       gtc->_depth != depth) {
-    // We need to reload a new image.
+    // We need to reload a new GL Texture object.
+    needs_reload = true;
+  }
 
+  if (!needs_reload) {
+    // Try to subload the image over the existing GL Texture object,
+    // possibly saving on texture memory fragmentation.
+
+    if (GLCAT.is_debug()) {
+      GLCAT.debug()
+        << "subloading existing texture object, " << width << " x " << height
+        << " x " << depth << ", mipmaps " << num_ram_mipmap_levels
+        << ", uses_mipmaps = " << uses_mipmaps << "\n";
+    }
+
+    for (int n = mipmap_bias; n < num_ram_mipmap_levels; ++n) {
+      const unsigned char *image_ptr = tex->get_ram_mipmap_image(n);
+      if (image_ptr == (const unsigned char *)NULL) {
+        GLCAT.warning()
+          << "No mipmap level " << n << " defined for " << tex->get_name()
+          << "\n";
+        // No mipmap level n; stop here.
+        break;
+      }
+
+      size_t image_size = tex->get_ram_mipmap_image_size(n);
+      if (one_page_only) {
+        image_size = tex->get_ram_mipmap_page_size(n);
+        image_ptr += image_size * z;
+      }
+
+      PTA_uchar bgr_image;
+      if (!_supports_bgr && image_compression == Texture::CM_off) {
+        // If the GL doesn't claim to support BGR, we may have to reverse
+        // the component ordering of the image.
+        image_ptr = fix_component_ordering(bgr_image, image_ptr, image_size,
+                                           external_format, tex);
+      }
+
+      int width = tex->get_expected_mipmap_x_size(n);
+      int height = tex->get_expected_mipmap_y_size(n);
+      int depth = tex->get_expected_mipmap_z_size(n);
+
+#ifdef DO_PSTATS
+      _data_transferred_pcollector.add_level(image_size);
+#endif
+      switch (texture_target) {
+      case GL_TEXTURE_1D:
+        if (image_compression == Texture::CM_off) {
+          GLP(TexSubImage1D)(page_target, n - mipmap_bias, 0, width,
+                             external_format, component_type, image_ptr);
+        } else {
+          _glCompressedTexSubImage1D(page_target, n - mipmap_bias, 0, width,
+                                     external_format, image_size, image_ptr);
+        }
+        break;
+
+      case GL_TEXTURE_3D:
+        if (_supports_3d_texture) {
+          if (image_compression == Texture::CM_off) {
+            _glTexSubImage3D(page_target, n - mipmap_bias, 0, 0, 0, width, height, depth,
+                             external_format, component_type, image_ptr);
+          } else {
+            _glCompressedTexSubImage3D(page_target, n - mipmap_bias, 0, 0, 0, width, height, depth,
+                                       external_format, image_size, image_ptr);
+          }
+        } else {
+          report_my_gl_errors();
+          return false;
+        }
+        break;
+
+      default:
+        if (image_compression == Texture::CM_off) {
+          if (n==0) {
+            // It's unfortunate that we can't adjust the width, too,
+            // but TexSubImage2D doesn't accept a row-stride parameter.
+            height = tex->get_y_size() - tex->get_pad_y_size();
+          }
+          GLP(TexSubImage2D)(page_target, n - mipmap_bias, 0, 0, width, height,
+                             external_format, component_type, image_ptr);
+        } else {
+          _glCompressedTexSubImage2D(page_target, n - mipmap_bias, 0, 0, width, height,
+                                     external_format, image_size, image_ptr);
+        }
+        break;
+      }
+
+      highest_level = n;
+    }
+
+    // Did that fail?  If it did, we'll immediately try again, this
+    // time loading the texture from scratch.
+    GLenum error_code = GLP(GetError)();
+    if (error_code != GL_NO_ERROR) {
+      if (GLCAT.is_debug()) {
+        GLCAT.debug()
+          << "GL texture subload failed for " << tex->get_name()
+          << " : " << get_error_string(error_code) << "\n";
+      }
+      needs_reload = true;
+    }
+  }
+
+  if (needs_reload) {
+    // Load the image up from scratch, creating a new GL Texture
+    // object.
     if (GLCAT.is_debug()) {
       GLCAT.debug()
         << "loading new texture object, " << width << " x " << height
@@ -7689,91 +7795,17 @@ upload_texture_image(CLP(TextureContext) *gtc,
 
       highest_level = n;
     }
-  } else {
-    // We can reload the image over the previous image, possibly
-    // saving on texture memory fragmentation.
 
-    if (GLCAT.is_debug()) {
-      GLCAT.debug()
-        << "subloading existing texture object, " << width << " x " << height
-        << " x " << depth << ", mipmaps " << num_ram_mipmap_levels
-        << ", uses_mipmaps = " << uses_mipmaps << "\n";
-    }
-
-    for (int n = mipmap_bias; n < num_ram_mipmap_levels; ++n) {
-      const unsigned char *image_ptr = tex->get_ram_mipmap_image(n);
-      if (image_ptr == (const unsigned char *)NULL) {
-        GLCAT.warning()
-          << "No mipmap level " << n << " defined for " << tex->get_name()
-          << "\n";
-        // No mipmap level n; stop here.
-        break;
-      }
-
-      size_t image_size = tex->get_ram_mipmap_image_size(n);
-      if (one_page_only) {
-        image_size = tex->get_ram_mipmap_page_size(n);
-        image_ptr += image_size * z;
-      }
-
-      PTA_uchar bgr_image;
-      if (!_supports_bgr && image_compression == Texture::CM_off) {
-        // If the GL doesn't claim to support BGR, we may have to reverse
-        // the component ordering of the image.
-        image_ptr = fix_component_ordering(bgr_image, image_ptr, image_size,
-                                           external_format, tex);
-      }
-
-      int width = tex->get_expected_mipmap_x_size(n);
-      int height = tex->get_expected_mipmap_y_size(n);
-      int depth = tex->get_expected_mipmap_z_size(n);
-
-#ifdef DO_PSTATS
-      _data_transferred_pcollector.add_level(image_size);
-#endif
-      switch (texture_target) {
-      case GL_TEXTURE_1D:
-        if (image_compression == Texture::CM_off) {
-          GLP(TexSubImage1D)(page_target, n - mipmap_bias, 0, width,
-                             external_format, component_type, image_ptr);
-        } else {
-          _glCompressedTexSubImage1D(page_target, n - mipmap_bias, 0, width,
-                                     external_format, image_size, image_ptr);
-        }
-        break;
-
-      case GL_TEXTURE_3D:
-        if (_supports_3d_texture) {
-          if (image_compression == Texture::CM_off) {
-            _glTexSubImage3D(page_target, n - mipmap_bias, 0, 0, 0, width, height, depth,
-                             external_format, component_type, image_ptr);
-          } else {
-            _glCompressedTexSubImage3D(page_target, n - mipmap_bias, 0, 0, 0, width, height, depth,
-                                       external_format, image_size, image_ptr);
-          }
-        } else {
-          report_my_gl_errors();
-          return false;
-        }
-        break;
-
-      default:
-        if (image_compression == Texture::CM_off) {
-          if (n==0) {
-            // It's unfortunate that we can't adjust the width, too,
-            // but TexSubImage2D doesn't accept a row-stride parameter.
-            height = tex->get_y_size() - tex->get_pad_y_size();
-          }
-          GLP(TexSubImage2D)(page_target, n - mipmap_bias, 0, 0, width, height,
-                             external_format, component_type, image_ptr);
-        } else {
-          _glCompressedTexSubImage2D(page_target, n - mipmap_bias, 0, 0, width, height,
-                                     external_format, image_size, image_ptr);
-        }
-        break;
-      }
-
-      highest_level = n;
+    // Report the error message explicitly if the GL texture creation
+    // failed.
+    GLenum error_code = GLP(GetError)();
+    if (error_code != GL_NO_ERROR) {
+      GLCAT.error()
+        << "GL texture creation failed for " << tex->get_name()
+        << " : " << get_error_string(error_code) << "\n";
+      
+      gtc->_already_applied = false;
+      return false;
     }
   }
 
@@ -7793,16 +7825,7 @@ upload_texture_image(CLP(TextureContext) *gtc,
     }
   }
 
-  // Report the error message explicitly if the GL texture creation
-  // failed.
-  GLenum error_code = GLP(GetError)();
-  if (error_code != GL_NO_ERROR) {
-    GLCAT.error()
-      << "GL texture creation failed for " << tex->get_name()
-      << " : " << get_error_string(error_code) << "\n";
-
-    return false;
-  }
+  report_my_gl_errors();
 
   return true;
 }
diff --git a/panda/src/gobj/texture.cxx b/panda/src/gobj/texture.cxx
index c128494399..fafafecb6c 100644
--- a/panda/src/gobj/texture.cxx
+++ b/panda/src/gobj/texture.cxx
@@ -705,7 +705,12 @@ reload() {
   if (_loaded_from_image && !_fullpath.empty()) {
     do_clear_ram_image();
     do_unlock_and_reload_ram_image(true);
-    return do_has_ram_image();
+    if (do_has_ram_image()) {
+      // An explicit call to reload() should increment image_modified.
+      ++_image_modified;
+      return true;
+    }
+    return false;
   }
 
   // We don't have a filename to load from.
@@ -2918,16 +2923,38 @@ do_unlock_and_reload_ram_image(bool allow_compression) {
     // properties have changed during the reload (for instance,
     // because we reloaded a txo), it won't contaminate the original
     // texture.
-    _x_size = tex->_x_size;
-    _y_size = tex->_y_size;
-    _z_size = tex->_z_size;
     _orig_file_x_size = tex->_orig_file_x_size;
     _orig_file_y_size = tex->_orig_file_y_size;
-    _num_components = tex->_num_components;
-    _component_width = tex->_component_width;
-    _texture_type = tex->_texture_type;
-    _format = tex->_format;
-    _component_type = tex->_component_type;
+ 
+    // If any of *these* properties have changed, the texture has
+    // changed in some fundamental way.  Update it appropriately.
+    if (tex->_x_size != _x_size ||
+        tex->_y_size != _y_size ||
+        tex->_z_size != _z_size ||
+        tex->_num_components != _num_components ||
+        tex->_component_width != _component_width ||
+        tex->_texture_type != _texture_type ||
+        tex->_format != _format ||
+        tex->_component_type != _component_type) {
+
+      _x_size = tex->_x_size;
+      _y_size = tex->_y_size;
+      _z_size = tex->_z_size;
+
+      _num_components = tex->_num_components;
+      _component_width = tex->_component_width;
+      _texture_type = tex->_texture_type;
+      _format = tex->_format;
+      _component_type = tex->_component_type;
+
+      // Normally, we don't update the _modified semaphores in a
+      // do_blah method, but we'll make an exception in this case,
+      // because it's easiest to modify this here, and only when we
+      // know it's needed.
+      ++_properties_modified;
+      ++_image_modified;
+    }
+
     _keep_ram_image = tex->_keep_ram_image;
     _ram_image_compression = tex->_ram_image_compression;
     _ram_images = tex->_ram_images;
@@ -2935,13 +2962,10 @@ do_unlock_and_reload_ram_image(bool allow_compression) {
     nassertv(_reloading);
     _reloading = false;
 
-    // Normally, we don't update the _modified semaphores in a do_blah
-    // method, but we'll make an exception in this case, because it's
-    // easiest to modify these here, and only when we know it's
-    // needed.
-    ++_image_modified;
-    ++_properties_modified;
-
+    // We don't generally increment the _image_modified semaphore,
+    // because this is just a reload, and presumably the image hasn't
+    // changed (unless we hit the if condition above).
+    
     _cvar.notify_all();
   }
 }
@@ -4022,9 +4046,9 @@ get_ram_image_as(const string &requested_format) {
           nassertr(_num_components != 3, CPTA_uchar(get_class_type()));
           component = _num_components - 1;
         } else if (format.at(s) == '0') {
-          newdata[p * format.size() + s] =  0;
+          newdata[p * format.size() + s] = 0x00;
         } else if (format.at(s) == '1') {
-          newdata[p * format.size() + s] = -1;
+          newdata[p * format.size() + s] = 0xff;
         } else {
           gobj_cat.error() << "Unexpected component character '"
             << format.at(s) << "', expected one of RGBA!\n";