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Inverted Luma Matte in Boris RED

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Daniel SkrobowskiInverted Luma Matte in Boris RED
by on Oct 28, 2012 at 8:08:52 pm

Hi, I am a Boris RED user, and I am wondering how to set an inverted luma matte (called "Luma Matte Inverted" in After Effects) as a track matte for any media. In After effects, all that you have to do is go down to the track that you are interested in, go to the "TrkMat" options, and select "Luma Matte Inverted." How would I do the same thing in Boris RED?

My purpose is to do some depth compositing with some z-pass material. By the way, does anybody know of a good tutorial/walk through of how to do depth compositing with RED?

Any help is appreciated.

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peter mcauleyRe: Inverted Luma Matte in Boris RED
by on Oct 29, 2012 at 4:11:11 pm

Hi Daniel,

In Boris RED, you will find that you can twirl open any track to reveal what we refer to as sub-tracks. When you do this you will see the following sub-tracks in this order, from bottom to top:

Media - Mask (face mask) - Face - Transformations group - Mask (shape mask) - Track Shape

The two mask sub-tracks are used to apply a matte / mask either pre transform or post transform. Here's how it works ... you can drag any track containing a media element (a binary bitmap mask shape or a soft/hard pixel matte or any combination thereof) onto either the pre or post transform mask tracks. If you place the mask media track on the face mask then the mask will move as the media is transformed. If you place the mask on the shape mask track, then the mask will remain static, regardless of any transforms that you apply to that shape track.

To invert the matte, you can click on the invert mask toggle button, which is located at the far right of the mask track, beside the keyframe control section of the timeline.

For depth compositing, you might want to experiment with the BCC Z-Blur filter - it was designed specifically for this task. If you load the filter and click on the Help button, this will launch a detailed PDF that will walk you through how to use the filter.



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Daniel SkrobowskiRe: Inverted Luma Matte in Boris RED
by on Oct 30, 2012 at 4:22:03 pm

Awesome! Thanks Peter,

I experimented with the Z-Blur filter. It is useful, but it does blur instead of straight mask, even when you have the blur amount set to the max.

I appreciated the help on tracks. I was able to set my z-pass image as a mask/matte for a track. I applied a color choker to the image so that I had contrasting white and black. However when the image is acting as a matte for a track, it doesn't recognize black as alpha/transparent and white as opaque. How do I fix this.

The reason that I know that the matte was working was because the z-pass image that i was using as a matte already had some alpha channel information/regions on it. Therefore I was able to see my masked media behind the portion of the image that was alpha/transparent.

What I am trying to do is take away the initial alpha channel info and set the highly contrasted white and black as opaque and transparent (respectively).

...any suggestions?

Thanks again,

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peter mcauleyRe: Inverted Luma Matte in Boris RED
by on Oct 31, 2012 at 2:28:03 pm

Hey Daniel,

Glad that helped.

So regarding the alpha issue ... keep this rule in mind: any track that is outputting alpha can be nested in the mask track of any other track (pre or post transform) to act as an alpha matte for that track. With that, I'd suggest the following steps:

• click on the monitor icon on the track with alpha to view the output of this track in another viewer so that you can ensure that this track is indeed outputting alpha / transparency. (if you have not done so already, you might want to enable the checkerboard option to view alpha information or you can set the viewer mode to alpha instead of rub)

• once you have confirmed that the track has alpha, you can move forward and nest this in the mask track of the track that you need to have the track matte. TO do this, just drag the track with alpha onto the mask sub-track of the second track

• if you need to invert the matte, you can click on the invert mask button, which is at the far right of the mask track

Please let me know if this helps.



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Daniel SkrobowskiRe: Inverted Luma Matte in Boris RED
by on Nov 2, 2012 at 2:48:41 am

Hey Peter,

Again, I appreciate any help that I can get with RED. Unfortunately, the ammount of help, documentation, and tutorials that you can get a hold of for RED is miniscule compared to what you can get for After Effects, but these forums are a good remedy for this situation.

I thought that I would post a summary of what I did for some simple depth compositing in RED for anybody else who might have the same needs.... My goal at this point would be to figure out whether or not the way I did things was the most effective way to do them.

My original goal was to do some depth compositing in Boris RED. I had some main/background footage, some z-depth footage, and some other footage that I wanted to depth composite (some smoke/dust in this case). Since I had the z-pass footage already, I didn't really need to use the BCC Z-Blur filter. However in order to use the z-depth footage, I had to raise the contrast of the luma information (crush it so that it showed highly contrasted whites and blacks only...), create alpha information for it, and, eventually, set it (the crushed z-depth with new alpha...) as a matte/mask for my dust media. Fortunately, there is a filter that does the first two things for you-BCC Make Alpha Key. This filter will basically crush the image for you, set alpha information for white vs. black, and provide additionally useful capabilities such as feathering your contrasting whites and blacks.
Once the z-depth footage had been edited with the BCC Make Alpha Key filter, I used it as a matte for my dust footage by dragging it (the z-depth...) onto the track mask (the first mask track that you see when you twirl down/expand a main track).

This is what worked for me (in my first test project). I might be a little wrong in my usage of some of the terms. If anyone wants to correct it, feel free.

Thanks again for all of the help. If anyone wants to add anything that they think would be helpful, please do. I would also be interested in knowing if there are more effective ways of doing RED.

Happy compositing,


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Trevor AsquerthianRe: Inverted Luma Matte in Boris RED
by on Oct 31, 2012 at 5:46:07 pm

If you need to convert color channels of a video track to an alpha channel then apply bcc make alpha to the video track that you want to work as a hicon.

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