--- a/render_png.h	Fri Jun 06 23:37:45 2008 +0300
+++ b/render_png.h	Sat Jun 07 05:05:18 2008 +0300
@@ -11,7 +11,11 @@
 /*
  * Build and return a render_png that can be used to render a PNG of the given struct render.
  *
- * This inspects the size and io properties of the struct render.
+ * The dimensions of the PNG image will be read from render. If render's I/O 
+ * was set using render_io_stream, then the PNG data will be written to that
+ * stream. If it was set using render_io_custom, then the write_fn will be
+ * called with chunks of PNG data, and flush_fn from time to time as a hint to
+ * flush the data, but this may be omitted.
  *
  * returns NULL on failure.
  */
@@ -20,7 +24,7 @@
 /*
  * Feed a full row of raw pixel data into the PNG image.
  *
- * buf must be struct render.img_w bytes wide.
+ * buf must be render.img_w bytes wide.
  */
 int render_png_row (struct render_png *ctx, unsigned char *rowbuf);