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I'm working on Blender VFX and I'm using a blur node. This weakens the colors and I am trying to use a Math:Multiply node to strengthen the colors. However, when I use this node, it turns the transparent background to black. Is there a node that strengthens colors but does not change the background, or a node that changes transparency based on how dark the image is.

EDIT:: Unfortunately, palkomino's answer doesn't really help. The RGB Curves node does nothing!

I need a result like the Math:Multiply node, but with a transparent background.

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  • $\begingroup$ Much thanks cegaton. I don't know what the problem was. $\endgroup$ – Nobodyknows2202 Jul 26 '16 at 14:08
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The problem is that the math node uses a value (=> grey dot) and not a color (=> yellow dot). You'd rather use a RGB Curves node (ShiftA => Color => RGB Curves) and change it's C value. This will give you what you want.

enter image description here Look at how the backdrop changes. The first time it's the normal render without any compositing. It still has an alpha channel. The second time it's with the math note. The alpha channel disappears. The third time it's with the RGB Curves node. The colors get strengthen but the alpha channel stays.

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  • $\begingroup$ You can also raise the rgb values of the rgb curves node. This lightens up your image as well. Just make sure they are all raised the same amount otherwise some colors will change. If this still doesn't work you can try raising the brightness value of the brightness node or lowering the gamma value of the gamma node (all to be found in the color menu). You can also use the mix node and set it to overlay. Plug your blur node into the first input and choose white as the second color. Note that the factor can go higher than 1.000 when you type your desired value in. $\endgroup$ – palkonimo Jul 26 '16 at 14:27
  • $\begingroup$ I also tried that. Messing with the RGB Curves doesn't change anything. $\endgroup$ – Nobodyknows2202 Jul 26 '16 at 15:15
  • $\begingroup$ Did you also try the other suggestions I made? Like mix node, gamma node or brightness node? $\endgroup$ – palkonimo Jul 26 '16 at 15:42

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