Blackmagic Forum

Very new to fusion and comping in general. I'm trying to put this city shot in the background and the girl standing on the hill in the foreground, I used the lumakeyer and spline tool to mask where I need. It looks pretty good but now I have this checkerboard in the background from the mask. How do I fix this?

Okay so the checkerboard thing was a viewing option...so now that's sorted, however the masked city is a lot brighter than the rest of the image, when applying a color corrector the whole image changes instead of just the city. Any Ideas?

Under options, you can check the Pre-divide/Post-multiply box.

Frank Feijen wrote:Under options, you can check the Pre-divide/Post-multiply box.

I did check that but there's still a glow around the mask compared to the rest of the image, faint, but I see it.

I'm trying to add smoke/fire to the buildings, don't know where to go from here..

First of all you need to put the citys background over another solid background - possible a sky. You shouldn't then have to premultiply the image. Also, where you have blurred the mask around the city you may find you get a slight black edge to the left and right of you background image. Personally I would use delta keyer on the city image to put it over a sky background and then copy some of the trees in the foreground to build up/hide the left side of the scene. Hope that helps.