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Using A High Contrast Clip As A Matte In Resolve Fusion Tab
Hello there,
I’m on a slow journey of discovery with Resolve 15, and have been trying to figure out how use a high contrast video clip as a matte within Resolve’s Fusion tab. I’ve found a handful of tutorials – using effects like ‘Channel Booleans’ – but I’m not having much success.
It’s easy enough for me to create shapes to use as masks, but I can’t figure out how to make a video clip act as a matte. I can’t help feeling there’s something incredibly simple that I’m missing, but I could really use a hand from someone who knows this stuff better.
Thanks in advance,
Christopher -
10 Replies
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Probably the easiest way is to use a ‘luma keyer’ tool on the hicon video source – which will then allow you to tweak ‘low’ and ‘high’ to extract the luminance selection you want to use as the key.
The output of the luma keyer can then be dragged to a ‘mask’ input of a merge tool and the key output of that luma keyer tool will act as a mask between FG and BG of the merge tool.
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Thank you so much for taking the time to reply Trevor, and for the frame grab!
I’m coming at this from twenty-odd years on Avid, so plenty to learn, but things are starting to click now.
I’d thought it would simply be a case of taking the hicon source, then feeding that into the blue matte pipe, but obviously that didn’t work.
Anyway, thanks once again!
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Oh I’m old school Avid too & there’s probably loads of other ways of doing this in Fusion
I’ve found that you can switch which mask channels are used in the merge tool too – ‘Settings’ tab and change channel to ‘Luminance’ use Low & high for clip/gain.
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Although this method makes sense, it’s overkill and you don’t need a luma keyer. The mask input of any tool can use the luminance of the source matte image and there are built-in tools to clip the black and white values of the luminance.
Simon Ubsdell
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Thank you Simon,
Am I right in saying that I have to feed the merge node with the hicon matte as both background AND effect mask?
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No, the matte image only goes into the Merge tool’s Mask input like so:
Note that every Fusion image processing tool has a Mask input so you can use the same technique with all of them. For example here I am using the same matte to mask a Blur:
And here it is masking a Color Corrector:
Simon Ubsdell
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Aah – okay, now I see from your screenshots what I was doing wrong. I wasn’t giving Resolve anything to actually ‘cut out’ with the matte. I was just expecting Fusion to give me transparency, which would carry along the next pipe, rather than give it a foreground to cut out over the background.
Thanks for taking the time to illustrate things so very clearly Simon – must’ve taken you a while to put together.
Cheers,
Chris -
No problem. Always happy to help with any questions about Fusion. I know it can be confusing to start with.
Simon Ubsdell
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Just to put a full-stop under this one, I was almost there with my original assumption that feeding a hicon source into the effect matte would give the right result.
Where I came unstuck was that the effect won’t work at all if you don’t have something – even if it’s blank – feeding the background of the merge node. That, and making sure that the Channel that it takes transparency from is the luma channel.
So if I try the following:
Then the matte doesn’t work.If I do the same, attaching a blank text node to the background:
The matte now works, and creates transparency on my foreground.Hope that helps someone who’s in a similar situation!
Thanks again to those who helped!
Chris -
I’m sorry, I hadn’t quite understood what you were trying to do. The easiest way to create transparency for an image using a matte source is to:
Add a Bitmap tool to the matte image and set the Channel to Luminance.
Pipe the output of the Bitmap tool into the mask input of the image you want to mask.
In the Mask tab of the Image check the Multiply by Mask button.
You now have an image with the transparency of the matte.
You can use the controls in the Bitmap tool to adjust the matte levels.
There you go. Just one of the approved methods for achieving this.
I hope you don’t mind me saying that although your method works, it’s not one that I would recommend.
Simon Ubsdell
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