Doom9's Forum - View Single Post - is there a function to ADD two clips (blend)

waka · 2nd November 2003, 12:16

Speaking from a yuv perspective.

Layer will average the two clips or (a+b)/2. Multiply the resulting values by two and you get the clips "added together".

a=????
b=????
layer(a,b,"fast")
coloryuv(gain_y=256,gain_u=256,gain_v=256)

However, chroma values are relatively close to 128 usually, so if you add them together you'll likely end up with values 200+ which will be a purple/orange mess. Also, "black" can have a significant luma value, ~16. Adding two "black" clips can result in a dark grey. Without knowing what you are trying to accomplish, the following might be suitable.

a=????
b=????
layer(a,b,"fast")
coloryuv(off_y=-16)
coloryuv(gain_y=256)
coloryuv(off_y=16)

2nd November 2003, 12:16	#4 \| Link
waka Registered User Join Date: Jul 2002 Posts: 29	Speaking from a yuv perspective. Layer will average the two clips or (a+b)/2. Multiply the resulting values by two and you get the clips "added together". a=???? b=???? layer(a,b,"fast") coloryuv(gain_y=256,gain_u=256,gain_v=256) However, chroma values are relatively close to 128 usually, so if you add them together you'll likely end up with values 200+ which will be a purple/orange mess. Also, "black" can have a significant luma value, ~16. Adding two "black" clips can result in a dark grey. Without knowing what you are trying to accomplish, the following might be suitable. a=???? b=???? layer(a,b,"fast") coloryuv(off_y=-16) coloryuv(gain_y=256) coloryuv(off_y=16) Last edited by waka; 2nd November 2003 at 12:21.