Thanks for all your thoughts.
I think Ivan is probably right. Even float has limits and I am using very
low colours there which I'm pushing very far up. Would love to see The
Foundry's take on this.


Ron Ganbar
email: [email protected]
tel: +44 (0)7968 007 309 [UK]
     +972 (0)54 255 9765 [Israel]
url: http://ronganbar.wordpress.com/



On 20 July 2011 19:18, Ivan Busquets <[email protected]> wrote:

> Actually, I think the reason it looks correct in 8 and 16 bit is
> because values hit 0 before they reach the edge of the "square sampled
> area".
> Which would be the same as clamping some of the very low end in a float
> image.
>
> The problem is, in the case of a radial gradient like this one, that
> the pixels at the corners are obviously further away from the center
> than say a pixel in the middle of the right edge. And indeed they get
> a smaller value because of it. BUT, the sampling region is square, so
> the X pixel coordinate at which they reach 0 is the same. If you were
> to use an Expression node instead of a gamma to show all pixels that
> are "not 0", you would see exactly the same problem.
>
>
> On Wed, Jul 20, 2011 at 10:58 AM, chris <[email protected]> wrote:
> >
> > yeah, strange.. the effect happens actually on any simple
> > blur... looks like the gaussian blur is not really spreading
> > uniformly, but more "boxy". boosting the quality level
> > doesn't help either. ironically, if you switch the filter to
> > box it gets more like a circle.
> >
> > also, if i replicate the same setup in shake, it looks like
> > a circle in 8 and 16bit, but gets wonky in float. so maybe a
> > gaussian blur is tricky to do in float?
> >
> > examples below
> > ++ c.
> >
> >
> > nuke:
> > *********
> >
> > set cut_paste_input [stack 0]
> > add_layer {rgba rgba.beta}
> > ColorWheel {
> >  inputs 0
> >  gamma 0.45
> >  name ColorWheel1
> >  selected true
> >  xpos -52
> >  ypos -353
> > }
> > Shuffle {
> >  red alpha
> >  green alpha
> >  blue alpha
> >  name Shuffle1
> >  selected true
> >  xpos -52
> >  ypos -268
> > }
> > Transform {
> >  scale 0.5
> >  center {960 540}
> >  name Transform1
> >  selected true
> >  xpos -52
> >  ypos -244
> > }
> > set N1e524f50 [stack 0]
> > Blur {
> >  channels rgb
> >  size 50
> >  filter box
> >  quality 80
> >  name Blur1
> >  label "size: \[value size]"
> >  selected true
> >  xpos -52
> >  ypos -203
> > }
> > Gamma {
> >  channels rgb
> >  value 8
> >  name Gamma1
> >  selected true
> >  xpos -52
> >  ypos -152
> > }
> > push $N1e524f50
> > Blur {
> >  channels rgb
> >  size 50
> >  quality 80
> >  name Blur2
> >  label "size: \[value size]"
> >  selected true
> >  xpos 65
> >  ypos -202
> > }
> > Gamma {
> >  channels rgb
> >  value 8
> >  name Gamma2
> >  selected true
> >  xpos 65
> >  ypos -148
> > }
> >
> >
> >
> > shake:
> > ******
> >
> >
> > ColorWheel1 = ColorWheel(1920, 1080, 4, 0, 1, 1, 1);
> > Bytes1 = Bytes(ColorWheel1, 2);
> > Reorder1 = Reorder(Bytes1, "aaaa");
> > Move2D1 = Move2D(Reorder1, 0, 0, 0, 1, 0.5, xScale, 0, 0, width/2,
> >    height/2, "default", xFilter, "trsx", 0, 0, 0.5, 0, 0, time);
> > Blur1 = Blur(Move2D1, 100, xPixels/GetDefaultAspect(), 0, "gauss",
> >    xFilter, "rgba");
> > Gamma1 = Gamma(Blur1, 8, rGamma, rGamma, 1);
> >
> >
> >
> >
> >
> >
> >
> > On 7/20/11 at 7:16 PM, [email protected] (Ron Ganbar) wrote:
> >
> >> Hi Randy,
> >> Still wrong on my end... :-(
> >> Played with Blur11 - didn't seem to make any difference.
> >> Thanks for trying.
> >>
> >> Ron Ganbar
> >> email: [email protected]
> >> tel: +44 (0)7968 007 309 [UK]
> >> +972 (0)54 255 9765 [Israel]
> >> url: http://ronganbar.wordpress.com/
> >>
> >>
> >>
> >> On 20 July 2011 18:12, Randy Little <[email protected]> wrote:
> >>
> >>> Merry Xmas its fixed.  The weird thing is that fixing was
> >>
> >> to turn off crop
> >>>
> >>> to format in the blur11 then turn it back on.   ?????  So
> >>
> >> I don't know.
> >>>
> >>> strange. maybe it was holding onto the format from pre
> >>
> >> crop some how for
> >>>
> >>> whatever reason.
> >>>
> >>> set cut_paste_input [stack 0]
> >>> version 6.2 v3
> >>> push $cut_paste_input
> >>> Sparkles {
> >>> size 30
> >>> motion 200
> >>> direction 60
> >>> fadeTolerance 152
> >>> broken_affected 6.6
> >>> broken_start 0.3
> >>> broken_holes 0.186
> >>> sparks_angle 77
> >>> name Sparkles1
> >>> selected true
> >>> xpos -111
> >>> ypos -205
> >>> }
> >>> Crop {
> >>> box {0 0 2048 1556}
> >>> name Crop4
> >>> selected true
> >>> xpos -106
> >>> ypos -157
> >>> }
> >>> Group {
> >>> name ExpoBlur2
> >>> selected true
> >>> xpos -106
> >>> ypos -103
> >>> addUserKnob {20 ExpoBlur}
> >>> addUserKnob {14 size R 0 5}
> >>> size 0.2
> >>> addUserKnob {41 strength T Grade160.white}
> >>> addUserKnob {41 curve T Grade160.gamma}
> >>> addUserKnob {41 black_clamp l "black clamp" T
> >>
> >> Grade160.black_clamp}
> >>>
> >>> addUserKnob {41 white_clamp l "white clamp" -STARTLINE T
> >>> Grade160.white_clamp}
> >>> addUserKnob {41 crop l "crop to format" T Blur11.crop}
> >>> }
> >>> Input {
> >>> inputs 0
> >>> name Input1
> >>> xpos 389
> >>> ypos -32
> >>> }
> >>> Dot {
> >>> name Dot328
> >>> xpos 423
> >>> ypos -4
> >>> }
> >>> set N1c441b60 [stack 0]
> >>> add_layer {rgba rgba.beta}
> >>> Blur {
> >>> size {{parent.size**7} {parent.size**7}}
> >>> crop {{parent.Blur11.crop}}
> >>> name Blur17
> >>> xpos 714
> >>> ypos 100
> >>> }
> >>> push $N1c441b60
> >>> Blur {
> >>> size {{parent.size**6} {parent.size**6}}
> >>> crop {{parent.Blur11.crop}}
> >>> name Blur16
> >>> xpos 589
> >>> ypos 96
> >>> }
> >>> push $N1c441b60
> >>> Blur {
> >>> size {{parent.size**5} {parent.size**5}}
> >>> crop {{parent.Blur11.crop}}
> >>> name Blur15
> >>> xpos 499
> >>> ypos 104
> >>> }
> >>> push $N1c441b60
> >>> Blur {
> >>> size {{parent.size**4} {parent.size**4}}
> >>> crop {{parent.Blur11.crop}}
> >>> name Blur14
> >>> xpos 389
> >>> ypos 106
> >>> }
> >>> push $N1c441b60
> >>> Blur {
> >>> size {{parent.size**3} {parent.size**3}}
> >>> crop {{parent.Blur11.crop}}
> >>> name Blur13
> >>> xpos 287
> >>> ypos 108
> >>> }
> >>> push 0
> >>> push $N1c441b60
> >>> Blur {
> >>> size {{parent.size*2} {parent.size*2}}
> >>> crop {{parent.Blur11.crop}}
> >>> name Blur12
> >>> xpos 174
> >>> ypos 108
> >>> }
> >>> push $N1c441b60
> >>> Blur {
> >>> size {{parent.size} {parent.size}}
> >>> name Blur11
> >>> xpos 53
> >>> ypos 115
> >>> }
> >>> Merge2 {
> >>> inputs 7+1
> >>> operation plus
> >>> name Merge243
> >>> xpos 389
> >>> ypos 232
> >>> }
> >>> set N1c474b50 [stack 0]
> >>> Grade {
> >>> channels rgba
> >>> white 1.02
> >>> gamma 0.435
> >>> white_clamp true
> >>> name Grade160
> >>> xpos 389
> >>> ypos 311
> >>> }
> >>> Output {
> >>> name Output1
> >>> xpos 389
> >>> ypos 438
> >>> }
> >>> push $N1c474b50
> >>> Viewer {
> >>> input_process false
> >>> name Viewer1
> >>> selected true
> >>> xpos 570
> >>> ypos 426
> >>> }
> >>> end_group
> >>>
> >>> Randy S. Little
> >>> http://www.rslittle.com <http://reel.rslittle.com>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>> On Thu, Jul 21, 2011 at 00:52, Ron Ganbar
> >>
> >> <[email protected]> wrote:
> >>>
> >>>> set cut_paste_input [stack 0]
> >>>> version 6.2 v4
> >>>> push $cut_paste_input
> >>>> Sparkles {
> >>>>  size 30
> >>>>  name Sparkles1
> >>>>  selected true
> >>>>  xpos -304
> >>>>  ypos 3346
> >>>> }
> >>>> Crop {
> >>>>  box {0 0 2048 1556}
> >>>>  name Crop4
> >>>>  selected true
> >>>>  xpos -304
> >>>>  ypos 3374
> >>>> }
> >>>> Group {
> >>>>  name ExpoBlur2
> >>>>  selected true
> >>>>  xpos -304
> >>>>  ypos 3422
> >>>>  addUserKnob {20 ExpoBlur}
> >>>>  addUserKnob {14 size R 0 5}
> >>>>  size 2
> >>>>  addUserKnob {41 strength T Grade160.white}
> >>>>  addUserKnob {41 curve T Grade160.gamma}
> >>>>  addUserKnob {41 black_clamp l "black clamp" T
> >>
> >> Grade160.black_clamp}
> >>>>
> >>>>  addUserKnob {41 white_clamp l "white clamp" -STARTLINE T
> >>>> Grade160.white_clamp}
> >>>>  addUserKnob {41 crop l "crop to format" T Blur11.crop}
> >>>> }
> >>>>  Input {
> >>>>  inputs 0
> >>>>  name Input1
> >>>>  xpos 389
> >>>>  ypos -32
> >>>>  }
> >>>>  Dot {
> >>>>  name Dot328
> >>>>  xpos 423
> >>>>  ypos -4
> >>>>  }
> >>>> set Nbb6ed990 [stack 0]
> >>>> add_layer {rgba rgba.beta}
> >>>>  Blur {
> >>>>  size {{parent.size**7 i} {parent.size**7 i}}
> >>>>  crop {{parent.Blur11.crop i}}
> >>>>  name Blur17
> >>>>  xpos 714
> >>>>  ypos 100
> >>>>  }
> >>>> push $Nbb6ed990
> >>>>  Blur {
> >>>>  size {{parent.size**6 i} {parent.size**6 i}}
> >>>>  crop {{parent.Blur11.crop i}}
> >>>>  name Blur16
> >>>>  xpos 606
> >>>>  ypos 103
> >>>>  }
> >>>> push $Nbb6ed990
> >>>>  Blur {
> >>>>  size {{parent.size**5 i} {parent.size**5 i}}
> >>>>  crop {{parent.Blur11.crop i}}
> >>>>  name Blur15
> >>>>  xpos 499
> >>>>  ypos 104
> >>>>  }
> >>>> push $Nbb6ed990
> >>>>  Blur {
> >>>>  size {{parent.size**4 i} {parent.size**4 i}}
> >>>>  crop {{parent.Blur11.crop i}}
> >>>>  name Blur14
> >>>>  xpos 389
> >>>>  ypos 106
> >>>>  }
> >>>> push $Nbb6ed990
> >>>>  Blur {
> >>>>  size {{parent.size**3 i} {parent.size**3 i}}
> >>>>  crop {{parent.Blur11.crop i}}
> >>>>  name Blur13
> >>>>  xpos 287
> >>>>  ypos 108
> >>>>  }
> >>>> push 0
> >>>> push $Nbb6ed990
> >>>>  Blur {
> >>>>  size {{parent.size*2 i} {parent.size*2 i}}
> >>>>  crop {{parent.Blur11.crop i}}
> >>>>  name Blur12
> >>>>  xpos 174
> >>>>  ypos 108
> >>>>  }
> >>>> push $Nbb6ed990
> >>>>  Blur {
> >>>>  size {{parent.size} {parent.size}}
> >>>>  name Blur11
> >>>>  xpos 53
> >>>>  ypos 111
> >>>>  }
> >>>>  Merge2 {
> >>>>  inputs 7+1
> >>>>  operation plus
> >>>>  name Merge243
> >>>>  xpos 389
> >>>>  ypos 283
> >>>>  }
> >>>>  Grade {
> >>>>  channels rgba
> >>>>  gamma 6
> >>>>  white_clamp true
> >>>>  name Grade160
> >>>>  xpos 389
> >>>>  ypos 311
> >>>>  }
> >>>> set Nc73fb7f0 [stack 0]
> >>>>  Viewer {
> >>>>  viewerProcess SHOWLinAsFilm3D
> >>>>  input_process false
> >>>>  name Viewer1
> >>>>  xpos 570
> >>>>  ypos 426
> >>>>  }
> >>>> push $Nc73fb7f0
> >>>>  Output {
> >>>>  name Output1
> >>>>  xpos 389
> >>>>  ypos 438
> >>>>  }
> >>>> end_group
> >>>>
> >>>
> >>>
> >>> _______________________________________________
> >>> Nuke-users mailing list
> >>> [email protected],
> >>
> >> http://forums.thefoundry.co.uk/
> >>>
> >> http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/
> >> nuke-users
> >>>
> >>
> >>
> >> -----
> >> _______________________________________________
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> >> http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/
> >> nuke-users
> >
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