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For the life of me cannot get transparency right

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rincewind153

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For the life of me cannot get transparency right

PostTue Aug 13, 2019 1:12 pm

I'm using Studio 16.

I have one full-screen image of Earth from space and another, smaller image of a capsule. I'd like to animate a number of capsules going from the Earth to the moon in succession (imagine dots moving on a map to represent traveling). Both images are png files.

I've managed to create the animation in Fusion with the following:

- I've created a background node
- Created Paint node and connected background node to it
- In the Paint node, I've added a PolylineStroke for the path that I want and loaded the capsule image
- I've keyframed "Write On" under Stroke Controls to get the "animation" going

This all works great, but the issue I'm having is that when I try to merge this with the background image of the Earth, all the capsules appear as half-transparent.

Image

I've tried different ways of using the capsule image. In the Paint node under Brush controls, I've tried Clip first, but that didn't work. I've then created a brush and got the same result.

If I play around with Apply Mode settings (in the Paint node), it's even worse (i.e. burnt colors). The closest thing to what I want is if I use the stamp mode. The capsule is then rendered correctly, but with a black border:

Image

I've tried various things to try and get rid of the black part, but no luck. It either gets worse or back to half-transparent (with the black part included).

I've tried creating a separate compound (and later fusion) clip just for the animation part. I've then added the main image on the timeline and the compound clip above it. When I change the Composite mode to "Add", it goes back to half-transparent again.

I've also tried saving the capsule image differently, either with black or white background and then with alpha transparency, but couldn't get none of them to work.

I'm not that experienced with Resolve yet, so I'm sure I'm missing something obvious. It can't be that hard to overlay a simple image without it being semi-transparent. Am I approaching this correctly by trying to use Paint node?

Any and all help is very appreciated, thank you!
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Sander de Regt

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Re: For the life of me cannot get transparency right

PostTue Aug 13, 2019 2:29 pm

In the loader of your PNG check the post multiply by alpha button (or something similar to this, I'm not at my Fusion right now) and see if it makes a difference. PNGs are notoriously finicky in that respect.
Sander de Regt

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Bryan Ray

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Re: For the life of me cannot get transparency right

PostTue Aug 13, 2019 4:41 pm

The Paint node paints the new stroke on top of the existing pixels. I think the trouble you're having is that the existing pixels from the Background node are black with a solid alpha: [0,0,0,1]. So your capsule's own alpha is essentially being ignored. (But do make sure it actually has an alpha channel.) I suspect that you can solve your problem by reducing the Alpha of the Background node to 0, so you're painting on a completely empty canvas instead: [0,0,0,0]. With that set, you should be able to just use a default Merge—Apply Mode: Normal and Operator: Over, Subtractive/Additive: 1, Alpha Gain: 1, and Blend: 1.

As Sander mentioned, PNG can be a weird format—by spec it's not premultiplied, so you may need to premult it yourself, but that's not always the case, so try it both ways and see which looks more correct.
Bryan Ray
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http://www.musevfx.com
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rincewind153

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Re: For the life of me cannot get transparency right

PostTue Aug 13, 2019 7:09 pm

Sander de Regt wrote:In the loader of your PNG check the post multiply by alpha button (or something similar to this, I'm not at my Fusion right now) and see if it makes a difference. PNGs are notoriously finicky in that respect.


Thank you for the suggestions. I did have that set, but after your comment and what Bryan wrote, I went and redid the png from scratch, which seems to have solved it. Check my reply below for more info.

Thank you again, really appreciate it.
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rincewind153

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Re: For the life of me cannot get transparency right

PostTue Aug 13, 2019 7:13 pm

Bryan Ray wrote:The Paint node paints the new stroke on top of the existing pixels. I think the trouble you're having is that the existing pixels from the Background node are black with a solid alpha: [0,0,0,1]. So your capsule's own alpha is essentially being ignored. (But do make sure it actually has an alpha channel.) I suspect that you can solve your problem by reducing the Alpha of the Background node to 0, so you're painting on a completely empty canvas instead: [0,0,0,0]. With that set, you should be able to just use a default Merge—Apply Mode: Normal and Operator: Over, Subtractive/Additive: 1, Alpha Gain: 1, and Blend: 1.

As Sander mentioned, PNG can be a weird format—by spec it's not premultiplied, so you may need to premult it yourself, but that's not always the case, so try it both ways and see which looks more correct.


Thank you, that was very helpful!

I went and double checked all the settings you've mentioned, and they were already set like that. So I figured it could only be something with PNG. So I deleted everything, all the nodes and began from scratch. I also made the image from scratch and saved it with a different software than what I used before - and it worked!

Now the capsules are no longer transparent and they show exactly as I want them to. So I guess something was going on with the PNG, although I've tried saving it before with different save settings and nothing helped.

If PNG files are finicky, is there a better solution for importing static images? I don't mind using some other format if it's more reliable to work with.

Thank you again, I'm really happy it's working now and you got me in the right direction
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Bryan Ray

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Re: For the life of me cannot get transparency right

PostWed Aug 14, 2019 3:35 pm

PNG is designed as a final export format for web and print publishing. It's not a good intermediate format. OpenEXR is the standard for VFX interchange, and most professional software supports it. If you lack the ability to save to EXR, probably the next best option is TIFF.

For a deep dive, I have this article:
http://www.bryanray.name/wordpress/anatomy-of-an-image/

The subhead "File Formats and Compression" starts about 60% of the way down the page. If you're unfamiliar with any of the terminology I use in that section, there's a good chance that the definitions are in the first part of the article.
Bryan Ray
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Chad Capeland

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Re: For the life of me cannot get transparency right

PostWed Aug 14, 2019 10:05 pm

rincewind153 wrote:I went and double checked all the settings you've mentioned, and they were already set like that. So I figured it could only be something with PNG. So I deleted everything, all the nodes and began from scratch. I also made the image from scratch and saved it with a different software than what I used before - and it worked!


Did you do this in both Fusion 16 and Fusion 9?
Chad Capeland
Indicated, LLC
www.floweffects.com
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rincewind153

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Re: For the life of me cannot get transparency right

PostThu Aug 15, 2019 4:14 pm

Chad Capeland wrote:Did you do this in both Fusion 16 and Fusion 9?


I only have Fusion 16, or do you mean something else with Fusion 9?
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rincewind153

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Re: For the life of me cannot get transparency right

PostThu Aug 15, 2019 4:21 pm

Bryan Ray wrote:PNG is designed as a final export format for web and print publishing. It's not a good intermediate format. OpenEXR is the standard for VFX interchange, and most professional software supports it. If you lack the ability to save to EXR, probably the next best option is TIFF.

For a deep dive, I have this article:
http://www.bryanray.name/wordpress/anatomy-of-an-image/

The subhead "File Formats and Compression" starts about 60% of the way down the page. If you're unfamiliar with any of the terminology I use in that section, there's a good chance that the definitions are in the first part of the article.


I'm using Photoshop for image editing. It doesn't seem to support VFX natively, but there seems to be a plugin for it.

Thank you for the article, it was a very good and informative read. Speaking of which, I've checked The book section on your page and most of the stuff seems to have been written for Fusion 9. How much of that is still applicable in Fusion 16?

Thanks again for all the help!
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Bryan Ray

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Re: For the life of me cannot get transparency right

PostThu Aug 15, 2019 8:36 pm

98% of it is still valid, but all of the screenshots and some of the hotkeys are outdated, thanks to the new UI. Most of it still applies to Fusion in Resolve, too, except for the I/O stuff near the beginning.

Once the iconography for the new interface has been sorted out, I'll get back to work on the second draft, but I'm not willing to spend the time on it until I know that my screenshots aren't going to be totally wrong just a few months later.
Bryan Ray
http://www.bryanray.name
http://www.musevfx.com

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