white balance

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  06 June 2014
white balance

i am trying out nuke. i would like to white balance an image by selecting a region of the image where i know that the original color is white/grey.

can i do this in nuke without making it brighter? just the colors.
 
  06 June 2014
A quick and dirty white balance would be color picking the white or grey spot into a constant node, invert that and merge/overlay with the original image.
Colorpicking in a color correction node's gain would work too.
 
  06 June 2014
i tryed colorpicking in colorcorrect gain and it make the image brighter.

i will try it with the constant node.
 
  06 June 2014
The most efficient (and standard) way of correcting the white balance is using a Grade node.

Click the white square next to the "white point" in the Grade node properties, then hold Ctrl and Shift, drag-select an area on the image which is supposed to be white.

To set the black level, click the black square next to the "black point" in the properties, then hold Ctrl and Shift, drag-select an area on the image which is supposed to be black.

If you view the result of the Grade node while picking the colors from the image, you may want to hold Alt together with Ctrl and Shift to make Nuke sample the source image instead of the modified result.

To preserve the brightness of the source image, set the "mix luminance" parameter of the Grade to 1
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Gregory Chalenko
Senior Compositor at NHB Studios Düsseldorf
IMDb | LinkedIn | Showreel | My R'n'D
 
  06 June 2014
Overlaying a colored Constant will actually produce a weird result. It's gonna multiply the colors darker than R0.5 G0.5 B0.5 with the color of the Constant (essentially, same as using the "gain" or "multiply" parameter in color correction tools), but for brighter colors, it's gonna perform the screen operation.
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Gregory Chalenko
Senior Compositor at NHB Studios Düsseldorf
IMDb | LinkedIn | Showreel | My R'n'D

Last edited by GringoFX : 06 June 2014 at 08:11 AM.
 
  06 June 2014
thank you. i will try.
 
  06 June 2014
i tried the whitepoint and blackpoint here. i wanted the left image to change into the right image inside nuke. no luck.

 
  06 June 2014
You should pick bright part of his shirt for the white point and dark part of her dress for the black point.
Alternatively, use the MatchGrade node
__________________
Gregory Chalenko
Senior Compositor at NHB Studios Düsseldorf
IMDb | LinkedIn | Showreel | My R'n'D
 
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