edge detection

#1

hi everyone,

since using edge mattes is important e.g. for blending edges of a foreground layer (after keying or when you use cg elements) into a background, there is suprisingly little information on the net about how to produce the best edge mattes. almost all compositing packages have some sort of edge detection that you can apply to your matte, but for some odd reason, you have no influence on the actual width of the edges they produce. I now about convolution kernel filters, but they are not very handy.

how do you create your edge mattes and how exactly do you make them thinner or thicker?
I sometimes use minimax or minimum, but I am sure there is a more elegant way.

I use combustion, after effects and fusion.

thanks

chris

#2

how about takeing your original matte shrink, extrude or erode it and subtract it from your original matte; or do some other logic operation with it. this gives you a lot of flexibility for your edge matte.

cheers,
-rayk

#3

Beyond of Hemmerli said you can use the Find Edges operator combined with others operators like matte controls (erode, dilate), minimax and Blur operators, in AE and Fusion (I believe) the procedure is “equal” or very close. You can obtain more control over edges gotten for this operators when you can select the algorithm used, possible in some softwares.

#4

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