video layer blending/stencilling

[Matt Ladkin]

hi there,

fairly new to video in qlab 3. im wondering if there is a way of creating a multilayered cue with a stencil effect of a layer.

I.E the bottom layer has a video file running on an output set to 100% opacity filling the screen and the layer above has a still image where i want the non-black image content to disappear showing the layer below (i.e the effect of putting a gobo into a lighting fixture)

I hope you understand what I am trying to achieve. In a PRG mBox media server it would be a digital gobo set to cut mode with the layer behind being draw onto stencil.

Thanks in advance,

Matt

[Christopher Ashworth]

Hi Matt,

You can use a still image with transparency to achieve this affect. For example, PNG images support transparency, and you can create an image with transparent sections to use as a stencil. Create a cue with it and you can use the cue's video layer to ensure it is always on top of other cues, and it will reveal the videos underneath it where the image is transparent.

Best,
Chris

[Joshua Langman]

You can also apply the image as a mask to the surface (or create a second surface that duplicates your "clean" version with this mask, and send any cues you want masked to that surface).

[Dave "luckydave" Memory]

On Thursday, July 18, 2013 at 11:18 PM, Joshua Langman wrote:

You can also apply the image as a mask to the surface (or create a second surface that duplicates your "clean" version with this mask, and send any cues you want masked to that surface). 

Note that surface image masks don't work with alpha channels, so in that image, use black and white for transparent/opaque areas. Black will be transparent, and white will show the cue.

-- 

luck...@figure53.com 

[Joshua Langman]

Perhaps one day all video cues can have Photoshop-style "blending modes," thereby letting you do on-the-fly chroma-keying and other compositing tricks. In this case, if you had a black and white image, you could set it to "multiply" and have an instant mask.

[micpool]

Unfortunately, as much as we all would wish it was so, there is currently no transparency in surface masks. As Los Bravos sang in 1967, "Black is Black, I want my underlying surface back"

On the plus side you can use greys in your jpeg so you can  do semi transparent bits, grads, and blur your masks for properly nice soft edges.

Mic