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Adjusting Alpha of Imported Image

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TKonings

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  • Joined: Thu Nov 08, 2018 3:43 pm
  • Real Name: Tom Konings

Adjusting Alpha of Imported Image

PostThu Nov 08, 2018 3:54 pm

Hi everyone,

Just getting started with Fusion, and loving it.

My question is this (and probably a very silly one at that): I dragged an image onto my Fusion workspace, which creates a MediaIn node.

How do I control the Alpha value of this image? I'd like it to be semi-transparent, so it shows the footage underneath this clip when I use it in the Edit Tab.

I suspect there's an easy answer to this, but I haven't been able to find it.

Thanks in advance.

Tom
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JP Docherty

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Re: Adjusting Alpha of Imported Image

PostThu Nov 08, 2018 5:10 pm

Add a Brightness/contrast node after the loader, uncheck Red, Green and Blue at the top then check Alpha. The gain control will then adjust only the alpha values - setting it to .5 will give you 50% transparency etc.
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TKonings

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  • Joined: Thu Nov 08, 2018 3:43 pm
  • Real Name: Tom Konings

Re: Adjusting Alpha of Imported Image

PostThu Nov 08, 2018 7:53 pm

Hmmm... I just tried that, but I must be doing something wrong.

I added the Brightness/Contrast Node after the MediaIn node that loads the image.
I unchecked the R, B and G channels and checked the A channel.

Unfortunately, lowering the gain control only brightens my image and does nothing to the transparency...

Am I missing something?
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Hendrik Proosa

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  • Location: Estonia

Re: Adjusting Alpha of Imported Image

PostThu Nov 08, 2018 8:40 pm

You must remove alpha premultiplication from RGB channels before messing with alpha and re-apply it afterwards, otherwise you turn linear blend into additive operation, thus brightened result. But as alpha stuff is kind of broken in Resolve, I wouldn't bet on it to work even if it should.
I do stuff.
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TKonings

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  • Real Name: Tom Konings

Re: Adjusting Alpha of Imported Image

PostThu Nov 08, 2018 8:52 pm

Alright, any tips on how to remove the aplha premultiplication? I'm still quite new to this...

Even so, this kinda sounds like a workaround to me - is there really no easy way to simply adjust the transparency of an image in fusion?

Thanks for the responses so far!
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Sander de Regt

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Re: Adjusting Alpha of Imported Image

PostThu Nov 08, 2018 9:17 pm

Tom, are you by any chance Dutch (or Flemish?) If so I'm considering offering Fusion assistance in Dutch for people who are just starting out with the program as a sort of private tutoring to help people get started with the immensely powerful program that is Fusion.
Let me know if this is something that might interest you.
Sander de Regt

ShadowMaker SdR
The Netherlands
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Frank Feijen

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  • Joined: Tue Dec 13, 2016 10:04 am
  • Location: Vilvoorde, Belgium

Re: Adjusting Alpha of Imported Image

PostThu Nov 08, 2018 10:30 pm

@Tom: you could merge it over a transparent background, in the merge-node you can then adjust the global transparancy of your mediaIn to taste?
Code: Select all
{
   Tools = ordered() {
      MediaIn1 = MediaIn {
         ExtentSet = true,
         CustomData = {
            MediaProps = {
               MEDIA_HEIGHT = 823,
               MEDIA_LAYER_DESC = {
               },
               MEDIA_MARK_IN = 0,
               MEDIA_MARK_OUT = 124,
               MEDIA_NAME = "vuilbak.png",
               MEDIA_NUM_FRAMES = 125,
               MEDIA_NUM_LAYERS = 0,
               MEDIA_PAR = 1,
               MEDIA_PATH = "E:\\00 Projecten\\Sputnik TV\\181026 Scheire onl slapen\\sources\\vectors\\vuilbak.png",
               MEDIA_SRC_FRAME_RATE = 25,
               MEDIA_START_FRAME = 0,
               MEDIA_WIDTH = 577
            },
         },
         Inputs = {
            GlobalOut = Input { Value = 124, },
            ["Gamut.SLogVersion"] = Input { Value = FuID { "SLog2" }, },
            Layer = Input { Value = "0", },
            ClipTimeEnd = Input { Value = 124, },
         },
         ViewInfo = OperatorInfo { Pos = { 110, 49.5 } },
      },
      Background1 = Background {
         Inputs = {
            GlobalOut = Input { Value = 124, },
            Width = Input { Value = 577, },
            Height = Input { Value = 823, },
            UseFrameFormatSettings = Input { Value = 1, },
            ["Gamut.SLogVersion"] = Input { Value = FuID { "SLog2" }, },
            TopLeftAlpha = Input { Value = 0, },
         },
         ViewInfo = OperatorInfo { Pos = { 110, 82.5 } },
      },
      Merge1 = Merge {
         Inputs = {
            Blend = Input { Value = 0.268, },
            Background = Input {
               SourceOp = "Background1",
               Source = "Output",
            },
            Foreground = Input {
               SourceOp = "MediaIn1",
               Source = "Output",
            },
            PerformDepthMerge = Input { Value = 0, },
         },
         ViewInfo = OperatorInfo { Pos = { 220, 82.5 } },
      },
      MediaOut1 = MediaOut {
         Inputs = {
            Index = Input { Value = "0", },
            Input = Input {
               SourceOp = "Merge1",
               Source = "Output",
            },
         },
         ViewInfo = OperatorInfo { Pos = { 330, 82.5 } },
      }
   }
}


@Sander: that sounds like a great plan to help the Fusion-growth in our low lands!
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TKonings

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  • Joined: Thu Nov 08, 2018 3:43 pm
  • Real Name: Tom Konings

Re: Adjusting Alpha of Imported Image

PostFri Nov 09, 2018 6:50 am

@Sander: I'm Dutch, and that sounds interesting. I'll get back to you on that (I'll send you a PM).

@Frank: Thanks, I'll give that a try!
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Sander de Regt

  • Posts: 963
  • Joined: Thu Nov 13, 2014 10:09 pm

Re: Adjusting Alpha of Imported Image

PostSat Nov 17, 2018 4:31 pm

Hi Tom,

DM/PM is fine. I'll be waiting for your message.
Sander de Regt

ShadowMaker SdR
The Netherlands

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