TIFFReadRGBAImage doesn't actually return errors unless you ask it to.

The final argument to TIFFReadRGBAImage is 'stopOnError'. That is,
if it's not true then the function will return success even if
loading the actual image data failed. As such, copying the example
code out of the documentation wasn't really what we wanted.

svn path=/trunk/theora/; revision=17856

examples/tiff2theora.c

@@ -410,7 +410,7 @@ tiff_read(const char *pathname,
     TIFFClose(tiff);
     return 1;
   }
-  if(!TIFFReadRGBAImage(tiff, width, height, raster, 0)) {
+  if(!TIFFReadRGBAImage(tiff, width, height, raster, 1)) {
     fprintf(stderr, "%s: error: couldn't read tiff data.\n", pathname);
     free(raster);
     TIFFClose(tiff);