1 Additive Key
ADDITIVE KEY is not an actual keyer but it is an image blending technique used to recover fine detail in difficult areas such as wispy hair, soft trasparencies and motion blur
If combined with a good matte, edge treatment and despill can create very good results to better integrate your plate to the bg
Additive Key manipulates lightness values in the fine details and ADDS it to the bg under the foreground plate
Additive Key/Divide/Mult
BG
For additive key we play with lightness
Lightness is NOT to be confused with Luminance
Lightness is the average of minimum and maximum values
Luminance is the sum of RGB
Change Linear color space to HSL whic is a 3 channel space
Shuffle the L (lightness) into Blue channel
Using colorplace and shuffle，shuffle lightness to B channel.
Obtain the detail by minus the despill from an average constant of the BG
We want to obtain opnly lightness so remove color information by playing with saturation
Use gain in grade node to control the lightness value information
Plus the Lightness value information together
mask the area of interest
Plus it over BG to merge lightness detail over bg and under fg
Den
Despill
Adjust the matte
Transparency multiply
2 Multiplied Trasparencies
By minus Original from despill plate you get the luminosity lost by removing green
- Desaturate that values to remove
unwanted colors
-Multiply the bg over those luminosity
values - Plus it over original to add
bg in the trasparencies
Matte
Use IBKcolor, select screen type, and adjust size
Adjust color grade and blur edges
3 – Color Correct Trasparencies
Hard inverted matte no soft trasparency
Color look up is like curves in photoshop
Select with roto areas of interest
Adujust Trasparency Grade
Difference key
