Something you don't know about Blending Mode, aka "matte-free" compositing

a. The blending operations below (1-4) are "SYMMETRICAL", which means you can swap the 2 input image without getting different results.

1. SCREEN MODE:
-double up the exposure (it shouldn't block the background)
-the Weighted Screen Operation (reduced the opacity of background, less opacity was seen, as the usual Screen operation might make the image looked pale and disaturated)
-good for lense flare, light glow, laser, light saber compositing


2. MULTIPLY:
-each image retain their "identity", a more punchy result is given


3. MAXIMUM (LIGHTEN):
-compare 2 image on a pixel by pixel basis. Whichever pixel is the maximum becomes the output
-good for fire (life footage) compositing


4. MINIMUM (DARKEN):
-the opposite of MAXIMUM

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b. COMPLEX BLENDING MODE:

SOME BASIC MATH AND EQUATIONS:

1. "A" (blend layer) over "B" (base layer)

"take complement of the base layer (B) and then multiply that by the blend layer (A)"

thus, the equation will be:

(1-B) x A

if "A" as "input 1", "B" as "input 2", the mythical math node as 3 channel equations will look something like this:

R channel out = (1- r1) x r1

G channel out = (1- g1) x g2

B channel out = (1- b1) x b2

2. "pseudo-code" is used here. you will have to convert the equations to the syntax for your package.

"*" for multiply

"+" for addition

"if/then" for square root

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1. OVERLAY:

- changes its behavior depending on its pixel value of the base layer color. if base layer color pixel is less then 0.5, it will do a Multiply operation; if more then 0.5, it switches to a Screen operation.

If (B <>

2 x A x B

else

1 - 2 x (1 - A) x (1 - B)

2. HARD LIGHT:

- changes its behavior depending on its pixel value of the blend layer color. if blend layer color pixel is less then 0.5, it will do a Multiply operation; if more then 0.5, it switches to a Screen operation.

If (A<0.5)>

2 x A x B

else

1 - 2 x (1 - A) x (1 - B)

3. SOFT LIGHT

- also changes its behavior depending on its pixel value of the blend layer color. Its visual result is similar to OVERLAY operation but the calculation is much more complicated:

If (A<0.5)>

2 x A x B + (B² x (1 - 2 x A)

else

sqrt(B) x (2 x A - 1) x 2 x B x (1 - A)

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more run down of other Photoshop blending modes, visit:

www.pegtop.net/dephi/blendmodes

UNKNOWN KEY WORD:
-Banding Effect

QUOTED FROM

DIGITAL COMPOSITING FOR FILM AND VIDEO, BY STEVE WRIGHT