Plugin Solutions For Final Cut Pro, Color, & Motion

G RGB Colour Mixer

G RGB Colour Mixer is a new way of manipulating the colours and tones of an image without using look-up tables (LUTs). It is especially suitable for creating the look of old film processes as well as very subtle film effects. The filter is fully Y’CbCr even though it works with RGB, and also has the option of working in linear gamma, which can produce different and better results than working in the normal gamma of video which is around 0.45. However in the initial code for G RGB Colour Mixer, the linearisation of the gamma in FCP was being done using LUTs, and these were producing artifacts. I changed the linear gamma mode to use instead a close approximation to the linearisation which gives many of the benefits of working in linear gamma, but also imparts a beautifully subtle S-shaped curve onto the video's tonal look, enhancing this filter’s use for creating Film Effects.

The filter works in three parts, the Gamma Controls, the + Channel Mixer and Overall Controls:

Gamma Controls
The Gamma Controls offer a new way of tonally balancing an image. The general method is to increase the Bright Strength and Dark Strength to around 100 or so, and then adjust the Mid-Tone Point until the image looks balanced. For effect you can change the Bright / Dark Blending to harshen or soften the transition from dark to bright. To finally tweak the effect, change the Bright and Dark Strength and the other controls until you are happy.

+ Channel Mixer
The + Channel Mixer allows you to change the balance and composition of the Red, Green and Blue channels that make up the image. Normally these channels are kept separate, but with the mixer you can add in, say, the blue channel to the red by increasing the +Blue Mix in the +Red Properties section. You can also select from a number of presets so that you can get the feel of what kinds of effects can be created with this filter. The Brightness Balance control will adjust the relative brightness of the new Red, Green and Blue channels you have created to help you keep the effect producing the overall tonal look you want. By adjusting the Inter Channel Balance you can allow more or less of the effect to come through, and this will also aid in keeping the overall colour balance of the effect correct.


Overall Controls
The Overall Controls effect the entire image after both gamma and channel mixing. The Original Luma control will allow the original luma of the image before it has been filtered through to be seen in the final result. This can tone back an effect, or limit the effect to the chroma of the image. Overall brightness is just that, a brightness control. Fine Phase is a control that adjusts the colour balance of the entire image with a fine degree of control, and finally, Saturation will either saturate or de-saturate the image.
Because this filter works so well to create a Film Effect, it has been combined with G Film to produce G Film Extra so that you can use it conveniently.

Work In Linear Gamma
Selects whether you’d like this effect to work in linear gamma or not. See above - this is nor precisely linear and does impart a very nice S shaped gamma curve onto the video as part of it’s operation.
Bright Strength
-100% to 200%
Controls the strength of the brightening of the image - negative values darken.
Mid-Tone Point
0% to 100%
Increase or decrease to balance the tones of the image.
Bright / Dark Blending
0% to 100%
Harshen or soften the transition from the bright to the dark areas of the image.
User Control
These presets govern the +Red Properties, +Green Properties and +Blue Properties only. They can be altered with the Brightness Balance and Inter Channel Balance controls. User Control allows you to make your own mix of R, G and B.
Brightness Balance
-200% to 200%
Controls the relative brightnesses of the RGB mix.
Inter Channel Balance
-400% to 400%
Controls the RGB mix to help you preserve colour balance.

Red Properties
+ R Mix
+ G Mix
+ B Mix

0% to 200%

Set the relative mix of RGB that makes up the final Red channel of the mix.

Green Properties
+ R Mix
+ G Mix
+ B Mix

0% to 200%

Set the relative mix of RGB that makes up the final Green channel of the mix.

Blue Properties
+ R Mix
+ G Mix
+ B Mix

0% to 200%

Set the relative mix of RGB that makes up the final Blue channel of the mix.
Original Luma
0% to 100%
Blend back into the final result the luma of the original un-effected image.
Overall Brightness
0% to 400%
Controls the overall brightness of the image.
Fine Phase
-100% to 100%
Controls the phase of the image with a very fine degree of control.
0% to 500%

Controls the saturation of the image.
100% leaves the saturation alone.
0% is fully de-saturated.
200% is very saturated.
500% is extremely saturated.


©2007 Nattress Productions Inc.