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General Lighting Adjustment in Nuke

General Lighting Adjustment

 

Continuing this note from “Foreground Compositing in Nuke” which I posted 8th of Nov.

  bg

bg

We have the neutralizer color correction “Grade2” which is right under Transform node.

 Get the HueCorrect and drag and over the line between Grade2 and Keymix.

Screen Shot 2013-11-15 at 7.47.26 PM

To do HueCorrect, look to the HueCorrect node then put the mouse over to the area closer to the green screen and to see what color it is fall into.

greenScreen

new

On the edge of step here on the hue graph here the yellow line keeps indicating the value where the mouse is.

Screen Shot 2013-11-15 at 7.57.34 PM

Click the g_sup on the hue graph.

Screen Shot 2013-11-15 at 7.57.42 PM

It stops around 1.7 in the hue region. The section we want to pull down where the arrow is. You can’t drag this horizontally and vertically at the same time. Drag the point over the yellow line .

Screen Shot 2013-11-15 at 8.16.16 PM

Then you can pull it down to the control point and also pull down right to the next one to get rid of more of the green.Screen Shot 2013-11-15 at 8.21.43 PM

You can play around with the left control point to get some red back.

Now you can toggle off & on  the HueCorrect node. It looks natural and less green. However we pull the green light out it becomes darker.

To solve this problem:

compare

On the color figure, the angle of the circle is the hue, it is kind of unwrapped. So the result is  the reduction of luminance.

Screen Shot 2013-11-15 at 8.41.42 PM

One of the solution for this to go up to Luminance ( command+click on the Luminance curve) then reduce the brightness without reducing the green color..

Screen Shot 2013-11-15 at 8.46.55 PM

If you look at the set, the wall of background is not definitely white. There are some lights from the fountain or some bounce lighting seated on the wall. So the stair object should be tilted by interacting lighting by this wall.

Go to the “Grade2” node we added already and double click that, what we did with the node was to set black & white points base on the black and white cards on the set.

grade

What we can do is set the lift and gain back to where we want it. So press “G” to another node “Grade“.

This is time we are going to get a sample from the background.

Screen Shot 2013-11-15 at 9.08.37 PM

To start with the black point, crank the gamma all the way up for the darker part of the shot. In this case right on the fence would be a good one to try.

Screen Shot 2013-11-15 at 9.12.57 PM

Disable the Grade node we added then click the lift color swatch. To get the sample, drag the section in there. That would be represent the black point.

sample_node

sample

Click the gain color swatch then command+shift drag on the bright part of wall.

lift

Screen Shot 2013-11-15 at 9.25.20 PM

De-select the eyedropper and go back to the viewer,  command+click to dismiss the sample box. ( Always)

Click “d” to able the Grade node. It still look a bit yellow. Let’s start tweaking this.

result

Double click the “Grade3” then go to the gain. Click the color wheel button. What we are going to do is make the of  “Saturation” darker.

swathc

The result is this.

result2

Finally create a fall matte. Get the RotoPaint node.Screen Shot 2013-11-15 at 10.40.41 PM

Add another Grade node

Screen Shot 2013-11-15 at 10.51.55 PM

We do the same thing. Click on gain get some sample from the yellow area of the wall and adjust the whitepoint.

Screen Shot 2013-11-15 at 10.53.51 PM

It still needs a final tweak but for now you get the idea.

Screen Shot 2013-11-15 at 10.53.45 PM