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TOPIC: blend effect and alpha channel png picture movie

Re: blend effect and alpha channel png picture movie 1 month ago #193112

It should look like that scrauber, i chached the version to a newer one and it started to work ( did not realize it was THAT old )
Thank you for everyone that answered .

Re: blend effect and alpha channel png picture movie 1 month ago #193113

  • schrauber
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hugly wrote:
I don't understand what alpha construction that is, which shows content in Lightworks somehow, but not in Photoshop, premultiplied?

I only see that 0127.png is completely transparent in Lightworks.
With this configuration (in the previous example) of the Blend effect, the alpha values at the background input of the Blend effect seem to be ignored.


If the transparency of the dust in the blend effect should be adjustable:
I created a simple test effect that creates new alpha values. The alpha values are generated from the maximum values of the respective RGB values. The original alpha values are ignored.
Effect Download:
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Black creates Alpha 0.
White creates Alpha1.
Gray creates intermediate alpha values.

Example:
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Edit: Probably it would be useful if the user could switch the effect so that the alpha value is always 1 if the color is different from black. Or an adjustable threshold, offset, etc.
But I think in this particular case the simple version seems sufficient?
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Last Edit: 1 month ago by schrauber.

Re: blend effect and alpha channel png picture movie 1 month ago #193114

  • schrauber
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Another possibility is the "Lumakey" effect.
Disadvantage: Due to the wrong alpha values of 0127.png , the effect also outputs wrong alpha values, which could cause problems in possibly following effects.
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Re: blend effect and alpha channel png picture movie 1 month ago #193117

  • jwrl
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something cool wrote:
JWRL ...i tryed to install it but as i have never done it bewore it failed and gave me this error-code

That error code appeared because you are running an older version of Lightworks. Since the problem that ClampToEdge addresses won't occur in this effect I've reset the addressing to the default values for future users. If you download it now it will compile on older versions of Lightworks as well as current versions.

schrauber wrote:
Another possibility is the "Lumakey" effect.

Probably the simplest fix is to use the blend effect set to "Screen" mode. I wouldn't use a luma key because you can also get contouring and edge problems unless you're very lucky.

hugly wrote:
I think the only way to fix this (if it shows an undesired result) is to go back to Blender.

I agree. There definitely is something wrong with that image. It doesn't behave consistently in Lightworks, and it doesn't in Photoshop.
Last Edit: 1 month ago by jwrl.

Re: blend effect and alpha channel png picture movie 1 month ago #193118

  • RWAV
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Personally prefer working with discrete alpha - mush easier to manage and manipulate. And yes, it is strange Photoshop sees nothing in one of the files - will look at it in Affinity later - all my Photoshop installations are pre-cloud based versions - so a bit dated perhaps.

Possibly irrelevant to the current user and issue, but over time there have been problems with embedded .png alpha - can't recall the details other than khaver pointing to (I think) incorrect bit depth in source .png files - the attached is a fix-up for a user at that time, four plus years ago, using Fusion to make a new alpha from the .png's oddity.


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Re: blend effect and alpha channel png picture movie 1 month ago #193120

  • schrauber
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jwrl wrote:
Probably the simplest fix is to use the blend effect set to "Screen" mode..

Yes, the result is similar to the one in add mode, as shown in my post "
# 193108 ".
"something cool" is apparently happy with that.
However, when using the blend effect alone, the transparency of the dust cannot be changed in the blend effect, because this image only works at the background input (the dust and the black background both have alpha 0).
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Windows 10, 64 Bit
Intel i5-4440 (3,1 GHz) ; Intel HD Graphics 4600
Last Edit: 1 month ago by schrauber.

Re: blend effect and alpha channel png picture movie 1 month ago #193121

  • jwrl
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"Screen" will give a softer result than "Add", but it's all a matter of personal preference.

RWAV wrote:
Possibly irrelevant to the current user and issue, but over time there have been problems with embedded .png alpha - can't recall the details other than khaver pointing to (I think) incorrect bit depth in source .png files

It may very well be relevant. If so, it reinforces the belief that the problem stems from the original Blender render.
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