Why is upscaling false being ignored with the following template? 
foreach($page->images as $image) :
  $options = array(
    'quality' => 85,
    'upscaling' => false
  );
  $large_img = $image->width(800,$options);
  $thumb_img = $image->size(100,100,$options);
  $img .= '<a href="'.$large_img->url.'"><img src="' . $thumb_img->url .'"></a>';
endforeach;
The page I'm testing has images that are smaller than 800 but the linked versions are all 800px wide (and pixellated because they've been stretched).