TonyB <ben### [at] panamac-comnet> wrote:
:>btw, what's the difference between the post-procces focal blur and the
:>official pov focal blur?

: One is fast, the other is slow. :)

  That's not the only difference.
  The post-processing focal blur uses only the calculated pixel colors to
calculate the blurring and thus doesn't add any new information to the
image.
  The focal blur calculated while rendering is more accurate and can add
information to the image which would be invisible without focal blur (or
with post-processed focal blur).

  For example, consider the following scene:
  We have a red box in front of the camera and a green box just behind the
red one so the edge of the green box is just behind the edge of the red box,
so that the green box is not seen (but moving the camera just a bit will
make the edge of the green box to be seen behind the red box).
  Now, using post-processing focal blur will not make any part of the green
box visible, but using povray's focal blur can make the edge of the green
box a bit visible (depending on the location of the focal point, of course).
  Thus, povray's focal blur is physically more accurate.

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

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