Hi All,
Ivan is mostly correct.
If those of you who are familiar with the NDK and writing your own
plugins.. The Foundry has been kind enough to include the grade node
as an example plugin... if you take a look you will find the answer ;-)
from Garde.cpp:
-------snip----------
float G = gamma[z];
// patch for linux alphas because the pow function behaves badly
// for very large or very small exponent values.
#ifdef __alpha
if (G < 0.008f)
G = 0.0f;
if (G > 125.0f)
G = 125.0f;
#endif
-------snip-----------
Gamma, gets clamped above 125, and below 0.008.... It is a rounding
error, or prevention of whacky numbers..
As Ivan said, you can easily create your own Gamma with an Expression
node, it's a very simple equation.. possibly just use the Gamma() node..
maybe it doesn't clamp,
Ben Pierre ;-)
ColorWheel {
inputs 0
gamma 0.45
name ColorWheel1
selected true
xpos -8
ypos -17
}
set N1be3efc0 [stack 0]
Grade {
gamma 3.1
name Grade1
selected true
xpos 109
ypos 92
}
push $N1be3efc0
Expression {
temp_name0 inv_gamma
temp_expr0 1.0/gamma
expr0 pow(r,inv_gamma)
expr1 pow(g,inv_gamma)
expr2 pow(b,inv_gamma)
name Expression1
selected true
xpos -8
ypos 92
addUserKnob {20 User}
addUserKnob {7 gamma R 0 10}
gamma {{Grade1.gamma.main}}
}
On Jul 20, 2011, at 5:52 PM, Ron Ganbar wrote:
Hi al,
I made this little gizmo that makes a nice glowy look, which I
prefer to other glows. There's a gamma operator in there that
determines the falloff. If I push it up a lot I start to get this
square shape. This seems odd to me. Any idea why?
Script copied below.
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
Ron Ganbar
email: [email protected]
tel: +44 (0)7968 007 309 [UK]
+972 (0)54 255 9765 [Israel]
url: http://ronganbar.wordpress.com/
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