diff --git a/libvips/foreign/foreign.c b/libvips/foreign/foreign.c
index b4323b4e..e77ad718 100644
--- a/libvips/foreign/foreign.c
+++ b/libvips/foreign/foreign.c
@@ -2872,13 +2872,30 @@ vips_matload( const char *filename, VipsImage **out, ... )
  * @dpi: %gdouble, render at this DPI
  * @scale: %gdouble, scale render by this factor
  *
- * Render a PDF file into a VIPS image.  Rendering uses the libpoppler library
- * and should be fast.
+ * Render a PDF file into a VIPS image. Rendering uses the libpoppler library
+ * and should be fast. 
+ *
+ * The output image is always RGBA --- CMYK PDFs will be
+ * converted. If you need CMYK bitmaps, you should use vips_magickload()
+ * instead.
+ *
+ * Rendering is progressive, that is, the image is rendered in strips equal in 
+ * height to the tile height. If your PDF contains large image files and 
+ * they span several strips in the output image, they will be decoded multiple 
+ * times. To fix this, increase the the tile height, for example:
+ *
+ * |[
+ * vips copy huge.pdf x.png --vips-tile-height=1024
+ * ]|
+ *
+ * Will process images in 1024-pixel high strips, potentially much faster,
+ * though of course also using a lot more memory.
  *
  * Use @page to select a page to render, numbering from zero.
  *
  * Use @dpi to set the rendering resolution. The default is 72. Alternatively,
- * you can scale the rendering from the default 1 point == 1 pixel by @scale.
+ * you can scale the rendering from the default 1 point == 1 pixel by 
+ * setting @scale.
  *
  * The operation fills a number of header fields with metadata, for example
  * "pdf-author". They may be useful. 
@@ -2886,7 +2903,7 @@ vips_matload( const char *filename, VipsImage **out, ... )
  * This function only reads the image header and does not render any pixel
  * data. Rendering occurs when pixels are accessed.
  *
- * See also: vips_image_new_from_file().
+ * See also: vips_image_new_from_file(), vips_magickload().
  *
  * Returns: 0 on success, -1 on error.
  */
diff --git a/libvips/foreign/pdfload.c b/libvips/foreign/pdfload.c
index 77f32029..04414c3c 100644
--- a/libvips/foreign/pdfload.c
+++ b/libvips/foreign/pdfload.c
@@ -242,9 +242,10 @@ vips_foreign_load_pdf_generate( VipsRegion *or,
 		r->left, r->top, r->width, r->height ); 
 	 */
 
-	/* Poppler won't always paint the background.
+	/* Poppler won't always paint the background. Use 255 (white) for the
+	 * bg, PDFs generally assume a paper backgrocund colour.
 	 */
-	vips_region_black( or ); 
+	vips_region_paint( or, r, 255 ); 
 
 	surface = cairo_image_surface_create_for_data( 
 		VIPS_REGION_ADDR( or, r->left, r->top ), 
diff --git a/libvips/foreign/svgload.c b/libvips/foreign/svgload.c
index a26f820d..67229efa 100644
--- a/libvips/foreign/svgload.c
+++ b/libvips/foreign/svgload.c
@@ -161,6 +161,10 @@ vips_foreign_load_svg_generate( VipsRegion *or,
 	cairo_t *cr;
 	int x, y;
 
+	/* rsvg won't always paint the background.
+	 */
+	vips_region_black( or ); 
+
 	surface = cairo_image_surface_create_for_data( 
 		VIPS_REGION_ADDR( or, r->left, r->top ), 
 		CAIRO_FORMAT_ARGB32, 
@@ -431,7 +435,6 @@ vips_foreign_load_svg_buffer_class_init(
 {
 	GObjectClass *gobject_class = G_OBJECT_CLASS( class );
 	VipsObjectClass *object_class = (VipsObjectClass *) class;
-	VipsForeignClass *foreign_class = (VipsForeignClass *) class;
 	VipsForeignLoadClass *load_class = (VipsForeignLoadClass *) class;
 
 	gobject_class->set_property = vips_object_set_property;