After lecture, I was still not completely certain about the meaning of this image as a "residual," and I was not entirely certain how to interpret the residual image. I would think that for a very good rendering, the image would be entirely black. Of course I know this would be unlikely especially at boundaries, so my next thought would say that a good rendering would only see residuals at the boundaries of surfaces and shadows? However, this image has residuals all throughout the image.
I guess more generally: I am impressed by how remarkably similar to the original image the rendering is. After considering the residual image, should I be less impressed by the performance?