Alpha channel problems - alpha track appears "transparent"?

rkm82 wrote on 3/22/2019, 10:01 PM

Hello guys

I'm going crazy here - I've been trying to get an alpha channel to work but it seems like I'm making some sort of error.

I have a background track ("mixing desk" image), I have the "alpha track" (suit over black alpha).

I go to properties => select the alpha channel (I've tried premultiplied first, but tried basically everything else).

Then in the alpha track => compositing mode I go to "screen" (the only thing that yields a result) => and I DO get an overlaying image, unfortunately it appears "semi-transparent" (see last image).

I played with every setting I could think of, but nothing works... what am I doing wrong?

Vegas 16.0 / B 361

Thanks guys...
 

 

Comments

fr0sty wrote on 3/23/2019, 12:36 AM

You do not want to set it to screen. If that is the only thing yielding a result, your source footage does not have an alpha channel, assuming you've right clicked on the footage and specified premultiplied or straight alpha from that properties menu. Source alpha should work. (detection of a clip's alpha channel should be more automatic, Magix)

Last changed by fr0sty on 3/23/2019, 12:41 AM, changed a total of 4 times.

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Grazie wrote on 3/23/2019, 1:49 AM

@fr0sty Yes. screen will give you that.

@rkm82 How do you know “Black Suit” has got an ALPHA channel? Did you create it?

fan-boy wrote on 3/23/2019, 4:26 PM

@rkm82

No Chroma key is used . No other Blend Mode should be used , when the image has an Alpha Channel . Keep Blend Mode set to Default "Source Alpha" , ie : the alpha channel of the source image is used to "make the blend" . And keep all opacity sliders set to 100 % . sure ,if you want to blend differently , then choose a different Blend Mode . But , if you want Only the Alpha channel to do the Blending , then keep Blend Mode set to "Source Alpha" . The Alpha channel is used as a "Blend Map" .

rkm82 wrote on 3/24/2019, 12:10 AM

Thanks for the replies guys -

Hmmm... well to be quite frank, I was TOLD that this file does have an alpha channel - not sure if that's the case, though...

Does anyone happen to have a test file laying around that definitely DOES have an alpha channel, so I could test? That would be fantastic.... :-) Thanks guys

Grazie wrote on 3/24/2019, 12:27 AM

@rkm82 - I think/believe you’ve already done all the Tests 😉 . What type of file is Blue Suit? JPG, PNG or what? Or is it a VIDEO?

Grazie wrote on 3/24/2019, 2:09 AM
Hmmm... well to be quite frank, I was TOLD that this file does have an alpha channel - not sure if that's the case, though...

@rkm82 - OK, I tested a freshly made Video File (a newly Rendered QT with ALPHA Channel) against a file which I KNOW hasn't got any ALPHA. I interrogated with MediaInfo ( Free downloadable Utility. If you ain't got it, GET IT NOW!) and this is what I can see:

 

 

I can see that the QT render has RGBA and it's that all important "A" that confirms to me that there is an ALPHA= Transparent Channel within its creation.

Get MediaInfo . . . . 😉

Last changed by Grazie on 3/24/2019, 2:13 AM, changed a total of 2 times.

Grazie

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fan-boy wrote on 3/24/2019, 2:26 PM

@rkm82

my previous Post said how to verity if a clip has a mask in the Alpha channel .

use Mask Generator .

Mask Generator allows viewing of all 4 channels , RGBA Red Green Blue Alpha .

scroll down to select Alpha . if Alpha is Solid White , then the footage doesn't have a 4th channel(alpha ) and Vegas defaults to Solid White . Or , the footage has a 4th channel( alpha ) and it is Solid White . Thus , Solid White alpha channel can occur for those two reasons , When inspecting with Mask Generator . Just to be clear , technically Mask Generator doesn't verify a 4th channel( alpha ) is actually part of the footage . Mask Generator does show a Black and White Mask image when an alpha channel is present .

if all else fails , you could use Chroma key to "cut the Black"

is it possible someone spoke of the Black matte as if it was an alpha channel ? If so , you can cut the Black with Chroma Key . If so , the person and the black are all part of the main image RGB channels , and the image has No 4th channel . Mask Generator can verity that too . just inspect R G B channels , it will be obvious .

in other words , there are green screens , blue screens , and you have a black screen ( No 4th channel )

Grazie wrote on 3/24/2019, 3:08 PM

@fan-boy I’ll give your approach with my QT file. Thank you. As to doing the CHROMA for Black, could get messy.

fan-boy wrote on 3/24/2019, 3:34 PM

Grazie , Vegas does have some low level tools that are handy . Mask Generator is a biggie . Not just for making masks , as the name implies . Cutting Black is harder to do then cutting Green ? I thought maybe there could be an advantage to cutting Black , I don't really know .

I use Mask Generator more often to inspect channel content , then for making masks .

Grazie wrote on 3/26/2019, 6:43 AM

Grazie , Vegas does have some low level tools that are handy . Mask Generator is a biggie .

@fan-boy - I promised to check out MG with my QT file, knowing it DID have an ALPHA. According to MG it doesn’t. Here’s the thing: I HAD to reveal the file having an ALPHA in its Properties. So, I’m guessing, if I couldn’t reveal it as having an ALPHA channel in Properties, then it didn’t and thusly, no requirement to use MG 😉.

TAXI!