fastnoise alpha behaviour

im trying to create a starfield with the fastnoise tool. i just cant get the alpha right. if i check the fastnoise tool it all looks good, also the alpha channel, but when i merge it with a background it all looks wrong, as if the alpha is partly inverted/ignored.

Code: Select all

{
   Tools = ordered() {
      FastNoise1_1 = FastNoise {
         Inputs = {
            GlobalOut = Input { Value = 124, },
            Width = Input { Value = 5000, },
            Height = Input { Value = 2000, },
            Depth = Input { Value = 3, },
            ["Gamut.SLogVersion"] = Input { Value = FuID { "SLog2" }, },
            Detail = Input { Value = 10, },
            Contrast = Input { Value = 5, },
            Brightness = Input { Value = -3.44, },
            XScale = Input { Value = 170, },
         },
         ViewInfo = OperatorInfo { Pos = { 1391.99, 58.3041 } },
      },
      Background2_1 = Background {
         Inputs = {
            GlobalOut = Input { Value = 124, },
            Width = Input { Value = 5000, },
            Height = Input { Value = 3000, },
            ["Gamut.SLogVersion"] = Input { Value = FuID { "SLog2" }, },
            Type = Input { Value = FuID { "Corner" }, },
            TopLeftRed = Input { Value = 0.011764707043767, },
            TopLeftGreen = Input { Value = 0.235294133424759, },
            TopLeftBlue = Input { Value = 0.584313750267029, },
            TopRightRed = Input { Value = 0.00392156885936856, },
            TopRightGreen = Input { Value = 0.231372565031052, },
            TopRightBlue = Input { Value = 0.521568655967712, },
            BottomLeftRed = Input { Value = 0.36823844572569, },
            BottomLeftGreen = Input { Value = 0.26004, },
            BottomLeftBlue = Input { Value = 0.591, },
            BottomRightRed = Input { Value = 0.184313729405403, },
            BottomRightGreen = Input { Value = 0.160784319043159, },
            BottomRightBlue = Input { Value = 0.333333343267441, },
         },
         ViewInfo = OperatorInfo { Pos = { 1204.18, 242.755 } },
      },
      Merge5_1 = Merge {
         CtrlWZoom = false,
         Inputs = {
            Background = Input {
               SourceOp = "Background2_1",
               Source = "Output",
            },
            Foreground = Input {
               SourceOp = "FastNoise1_1",
               Source = "Output",
            },
            SubtractiveAdditive = Input { Value = 0, },
            PerformDepthMerge = Input { Value = 0, },
         },
         ViewInfo = OperatorInfo { Pos = { 1390.19, 242.953 } },
      }
   }
}

i tried to pre divide/post-multiply, or make the alpha black and screen it in the merge, invert/subtract it with channel booleans, but without succes so far.

what am i missing?

I think you're geting negative values or something?
Switching your imagedepth to int16 instead of float16 seams to help. Alternatively, put a bitmapnode after your fastnoise.

Switching the imagedepth didn't work for me, but the bitmap did. thanks