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I'm trying to add parts of a blurred picture over the crisp version of the picture. I want to create a blurred corners effect.

This is the original picture: Original

This is the vignette I want to overlay: Vignette

I tried to combine the two using Alpha Over, but the blurred version doesn't show: Alpha Over

I tried using Mix with a variety of modes (Add, Overlay, Multiply), but I don't get the right results. Multiply is closest but too dark: Mix

I tried adding a Set Alpha node in various places, but if that's the solution, I don't know where to put it.

How can I layer the vignetted image over the original image?

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It's super easy. Just use the mask as the factor in a mix node.

Mask as a mix factor

*) Keep in mind that a masked mix will never look like a proper Depth of Field effect. If that's your intention, I'd recommend you to try cycles DoF instead.

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  • $\begingroup$ When I do that, I get this: i.stack.imgur.com/OowYN.jpg If I put the ellipse mask directly as the factor, it works, but I want to blur the ellipse. (Noted about DoF; at this point, I'm just trying to do the mask.) $\endgroup$ – Aubrie Oct 17 '16 at 3:43
  • $\begingroup$ (Finally got around to taking a closer look at your suggestion today) Got this: i.stack.imgur.com/avF9O.jpg Had to adjust my mask settings because the black-and-white gradient preview wasn't true to the actual effect, but otherwise works great. Thank you! $\endgroup$ – Aubrie Oct 19 '16 at 3:30
  • $\begingroup$ @Aubrie: Glad you solved it. btw, I'm curious about your node setup. It seems to have a couple of redundant nodes that can be optimized, unless you have a reason for them. For instance, don't load the image twice, just plug two noodles from the same socket. Also, why the passes render? The effect you're trying to achieve works fine if you pull the defocused and the "normal" version of the render from the combined socket. Also, check where your composite node is placed. In your setup it means that only the combined socket will be saved to disk from the render output when you save animation $\endgroup$ – Gez Oct 20 '16 at 14:44
  • $\begingroup$ Oh, sorry. I was looking at the first one. The only issues in the final one are the placement of the composite node and the unnecessary pass compositing (maybe you reserved them for some adjustment later, idk) $\endgroup$ – Gez Oct 20 '16 at 14:46
  • $\begingroup$ Thanks for asking! I am unequivocally a Blender noob, so I was working on an exercise to learn compositing: cgcookie.com/exercise/compositing-a-coffee-scene That's what the unnecessary passes are for. I'll be sure to redirect everything to the composite node before I export. Now to try Cycles DoF as you suggested. Thanks again! :) $\endgroup$ – Aubrie Oct 22 '16 at 18:50
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Use the blurred ellipse mask as alpha with the set alpha node.

I guess you wanted the white to be none blurred, hence the following Invert node with Alpha checked.

enter image description here

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  • $\begingroup$ This solution is correct, although it's a bit over-complicated for this particular case. The default mix node IS an alpha over, and using the mask to control the mix factor does the same with less nodes. $\endgroup$ – Gez Oct 17 '16 at 2:16
  • $\begingroup$ Now that you added the alternative OP can choose. I tried to extend, what was tried already, but you are right nevertheless. $\endgroup$ – Leander Oct 17 '16 at 2:25

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