user37788: Sorry I'm new, i can't find a tutorial to do this: i have a normal video and another one that i would like to use as an alpha mask to 'smooth borders' in davinci resolve, here is an example of my mask

Can i do it on DaVinci Resolve? I suppose i should do it in Fusion, but can't figure out how.
Thanks

user23732: You can simply add it to Fusion, and then pipe the alpha video into a MatteControl node. Alternatively, if your image does not have an alpha, but is just black to white gradients, you have to first go into a bitmap node like this:

Now configure the bitmap node to use Luminance instead of Alpha as the channel:

Now you can use the output of that bitmap as a mask in the blue inputs of nodes, or as mentioned in the MatteControl.
Or if you're using a Merge, you could also pipe it into the mask input of the merge node.
You could in theory also pipe it into the blue mask input of the source footage, but that makes it so every instance of that footage will have the mask applied, so it's not reusable, which we generally try to avoid.
So you can see the full setup here: (Note that Garbage mask of the MatteControl has to be set to invert)


37788: <p>Sorry I'm new, i can't find a tutorial to do this: i have a normal video and another one that i would like to use as an alpha mask to 'smooth borders' in davinci resolve, here is an example of my mask</p>
<p><a href="https://i.stack.imgur.com/twA9G.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/twA9G.png" alt="enter image description here" /></a></p>
<p>Can i do it on DaVinci Resolve? I suppose i should do it in Fusion, but can't figure out how.</p>
<p>Thanks</p>
 23732: <p>You can simply add it to Fusion, and then pipe the alpha video into a MatteControl node. Alternatively, if your image does not have an alpha, but is just black to white gradients, you have to first go into a bitmap node like this:</p>
<p><a href="https://i.stack.imgur.com/VWO6d.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/VWO6d.png" alt="Mask image piped into bitmap node" /></a></p>
<p>Now configure the bitmap node to use Luminance instead of Alpha as the channel:</p>
<p><a href="https://i.stack.imgur.com/1UGYW.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/1UGYW.png" alt="Setting channel to luminance for bitmap" /></a></p>
<p>Now you can use the output of that bitmap as a mask in the blue inputs of nodes, or as mentioned in the MatteControl.</p>
<p>Or if you're using a Merge, you could also pipe it into the mask input of the merge node.</p>
<p>You could in theory also pipe it into the blue mask input of the source footage, but that makes it so every instance of that footage will have the mask applied, so it's not reusable, which we generally try to avoid.</p>
<p>So you can see the full setup here: (Note that Garbage mask of the MatteControl has to be set to invert)
<a href="https://i.stack.imgur.com/aTr6a.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/aTr6a.jpg" alt="Full node setup" /></a></p>
