[jfrancis]

Would it be practical to come up with some sort of measurement of minimum noticeable difference and be able to use it to stop a render? The software could compare the image pre and post update and if the change is less than some user settable level of significance you could call the image "done."

Is there any use in that?

[jfrancis]

...and I would relate this above idea to the ideas about per material or per region SL values raised in this thread
http://www.maxwellrender.com/forum/view ... =2&t=41707