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IBKColor

The IBK keyer differs from many other keyers in that, instead of using a single color picker, it uses an input image (a clean plate with just the color variations of the background) to drive the key. This generally gives you good results when working with uneven blue- or greenscreens.

The IBK keyer consists of two nodes: IBKColor and IBKGizmo. IBKColor creates the clean plate from the blue- or greenscreen image, and IBKGizmo pulls the key.

Note:  Pre-rendering output from IBKColor to some formats can result in loss of color information and incorrect results when the image is used as input to IBKGizmo. We recommended that the .exr format is used for pre-rendered images as it supports full float data, reducing loss of information.

As a general workflow guide:

1.   Connect the output from IBKColor to the c input of IBKGizmo.
2.   Attach the input of IBKColor, along with the fg input of IBKGizmo, to the original blue- or greenscreen image.
3.   Attach the bg input of IBKGizmo to your background image.
4.   Create two Viewers and view the output from both nodes side-by-side.
5.   Adjust the controls of IBKColor until you get a clean plate with nothing but the background colors.
6.   Adjust the controls of IBKGizmo until you are happy with the key.
7.   Connect the output from IBKGizmo to a compositing node, such as Merge, to composite the foreground over the background.

Inputs and Controls

Connection Type

Connection Name

Function

Input

1

The blue- or greenscreen image.

Output

unnamed

Connect this to the IBKGizmo node’s c input.

Control (UI)

Knob (Scripting)

Default Value

Function

Parameters Tab

screen type

screen_type

blue

Select green or blue depending on which one you have in the foreground image.

size

Size

10

Adjust the amount of color expansion.

darks

off

0, 0, 0

Adjust the color values to get the best separation between black and the screen type color. You want to be left with shades of the screen color and black only. Start by bringing down the value for blue if you’re using a blue screen, and the value for green if you have a green screen in the image. The erode and patchblack sliders should be set to 0 when you’re adjusting these values.

As a rule of thumb, if you have a dark green discolored area, increase darks g. Similarly, if you have a light red discolored area, increase the lights r value.

lights

mult

1, 1, 1

Adjust the color values to get the best separation between black and the screen type color. You want to be left with shades of the screen color and black only. Start by bringing down the value for blue if you’re using a blue screen, and the value for green if you have a green screen in the image. The erode and patchblack sliders should be set to 0 when you’re adjusting these values.

As a rule of thumb, if you have a dark green discolored area, increase darks g. Similarly, if you have a light red discolored area, increase the lights r value.

erode

erode

0

Increase this value if you still see traces of the foreground edge color in the output. This might be especially useful if, after adjusting the lights and the darks values, you’re still left with areas of discoloration. This is likely if your screen does not have a very saturated hue.

patch black

multi

0

After adjusting the darks and the lights, you can increase this value to remove all the black from the output image, if you want. This might be useful, for example, if you get blue/green artifacts in your composite.

Step-by-Step Guides

Image-Based Keying

Video Tutorials

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