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TOPIC: blend effect and alpha channel png picture movie

chrome keys alpha channel anomaly. 8 months, 2 weeks ago #192510

  • something cool
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In the picture are two pictures that both have a transparency alpha channel made in blender3d ( png ) What i wonder is that the cloud like ( dust ) picture that has a yellow color should be in the front but it stays on the backround at least the chrome key is set to foreground, but it still should have transparency and non-transparency in it so i wonder is there something lightworks could make to make it to be on the front as a dust cloud.
-if you look in the chore key editor the cloud stands out form the black so it should be non transparent, but why isisn´t the whole cloud in the front of the layers ?.
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Re: chrome keys alpha channel anomaly. 8 months, 2 weeks ago #192514

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Not sure what's going on from your image - Chroma Key uses a FG on a generally green or blue BG. Can't see that in the image.

If material has a valid alpha channel (LW supports embedded alpha in a video file and image file) then perhaps just using a blend tool will do the job.

Seems from what one can understand of your components the material is not suitable for a luma Key.
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Last Edit: 8 months, 2 weeks ago by RWAV.

Re: chrome keys alpha channel anomaly. 8 months, 2 weeks ago #192517

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Hello,

The results depend surely on the areas of transparency which are unknown to us and I wouldn't use Chromakey for that either. Why using a keyer for a simple blend? However, what happens if you cycle inputs in order to switch foreground with background, does that looks as you expect?

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Last Edit: 8 months, 2 weeks ago by hugly.

Re: chrome keys alpha channel anomaly. 8 months, 2 weeks ago #192531

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Render out your Blender image or sequence with a transparent background and an alpha channel. DON'T use a chromakey, but as briandrys suggests, simply use a blend effect. A chromakey is highly inappropriate in this context. It isn't designed to do what you need.

It's called chromakey because it uses chroma to generate the key, not the alpha channel.
Last Edit: 8 months, 2 weeks ago by jwrl.

Re: chrome keys alpha channel anomaly. 8 months, 2 weeks ago #192556

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thank you all for the answers, im not very familiar with all the effect options and now when i tryed blend it worket.

blend effect and alpha channel png picture movie 8 months, 1 week ago #192921

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I have two from png pictures forming movie clips that i try to layer on each other.
both have a alpha channel and at least what i have tested the pictures in blender3d they should really have a transparent and non-transparent areas within them.
I tryed to connect them usign blend as someone here suggested me to .
But no matter how i try i try the goldish cloud that is in the other picture , it will not go on top of the other layer no matter how i try to switch what picture is on front and what not. What could be the solution, should i use a blend mask in some way to make it use the alpha channel or is there a specific way i should install the blend to the png movie tracks ? .
Im missign somethign , but what is it ?
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Re: blend effect and alpha channel png picture movie 8 months, 1 week ago #192926

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Hello again,

Could it be that the black plane in V1 the car stands on is solid black?

Please cycle inputs to find out.
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Last Edit: 8 months, 1 week ago by hugly.

Re: blend effect and alpha channel png picture movie 8 months, 1 week ago #192927

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Another thought, one step back.

What format did you select for rendering in Blender?
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Re: blend effect and alpha channel png picture movie 8 months, 1 week ago #192947

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I have combined your two threads. They really are about the same topic.

It really doesn't look like either of those images is transparent. Here's what I suggested that you do. The image of the small boy has transparency, the image of the surf museum doesn't. The routing is like this.

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That gives a result like this.

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Those are screen grabs that I have just done to demonstrate this, so it should work for you too.

There are two immediate reasons that I can think of that you could be having problems. The first, as I suggested above, is that the foreground image isn't really transparent. If you can definitely rule that out, the second is that your routing needs adjustment. You may have the transparent video connected to the bg input of the blend effect. That seems unlikely, given the nature of your two images.

You should be able to blend those anyway, even without transparency. Try using the screen mode in the blend effect.
Last Edit: 8 months, 1 week ago by jwrl.

Re: blend effect and alpha channel png picture movie 8 months, 1 week ago #192988

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The pictures should have an alpha transparency channel in them, i can make the cloud be
seen behind the other picture , but not the other way around.
Here i show one picture that has free channel´s to be seen in blenders wiew window,
1 tranparent 2 color 3 green . some one on some forum sayed that it has the alpha channel IF it´s seen in the blender color wiew layer.as seen here in the middle picture .
in this other picture you can see that the cloud is on the back seen throw the tranparent image , but i can´t get be seen when adding it to the front.
Im beginnign to doupt that the other picture with the cloud has not an tranparency on it even if it´s seen
in blender´s color wiew mode . little confusing ,
how do i use blend sreening.
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Re: blend effect and alpha channel png picture movie 8 months, 1 week ago #192989

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here is the car picture , and under it is the cloud ? Im starting to wonder if the cloud png is just somehow wrong.

Re: blend effect and alpha channel png picture movie 8 months, 1 week ago #192992

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You have mentioned multiple times, starting from the headline, that the pictures should have transparency, but do they?

Things would be easier to understand if you would answer questions.

Do you use a format which is supported by Lightworks to contain alpha channel?

What happens if you cycle inputs (a screenshot would be helpful)?
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Re: blend effect and alpha channel png picture movie 8 months, 1 week ago #192993

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If one has two images with alpha and combines then with a single blend tools - one will be the BG and one the FG only the FG alpha will be used.

To use both alpha images one needs to daisy-chain the standard LW blend tool with the alpha image being the FG in both instances.

Please see the attached.


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Possibly jwrl may point you at a user VFX tools capable of double-alpha in one hit.
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Re: blend effect and alpha channel png picture movie 8 months, 1 week ago #192998

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RWAV wrote:
Possibly jwrl may point you at a user VFX tools capable of double-alpha in one hit.

I do have an effect that combines multiple layers with alpha which I haven't posted because there really isn't much point. I threw it together to meet an immediate need. It really doesn't work any better than having daisy chained blends would.

However I don't really think that any of us can help much more without knowing a lot more about what's going on. Try just editing one of your graphics into V1 over any background you wish on V2. Add a blend effect to V1. If it has a valid alpha channel the two images will blend. Add a new V1, and edit your other graphic into that then add a blend effect.

Once you've done that tell us what happened.

Re: blend effect and alpha channel png picture movie 8 months, 1 week ago #193023

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I tryed to give you the answer in reply 192988 .
and my other picture has tansparency if you look at the first picture at this session. the car picture is on the front and the cloud is seen at the back.
And i have managed to make tranparent picture composition on lightworks bewore, i even got an shadow catcher picture to work.
But the cloud is a point dencity from blender , but as in answer 19288 someonw sayed to me that if i can get the picture be shown in blenders wiewer in the color mode as i try to represent it in answer 192988, then there should be an working alpha channel and tranparency.
I tryed to answer directly to your question but as i attached a picture to the answer my answer got thrown in a un-noticaple place.
In my pictures i use png as a format and i have got them working bewore, but to get them work from blender you have to turn the png:s jrpg channel on this way it can contain the channel. THIS ASWER WAS FOR HUGLY 192992 I DID USE IT AS A QUICK REPLY BUT IT LANDET HERE .
Last Edit: 8 months, 1 week ago by something cool.
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