CG Jam

Bokeh image input

Whats it for??- Bokeh image input node.

we’ve seen the bokeh blur node, so what the hell is this for??

Whats it for?- Bokeh image input.

In our last episode we looked at what is bokeh and how the camera aperture can affect the shape of light sources. well this node is what we can use to re create the shape of the aperture. this is useful if your using blenders 3d camera to render an image and you need your background image to be blurred the same way.or if you are compositing several images together and you want the bokeh effects to match up. this node makes it fairly simple.

To use this node it simply plugs in to the bokeh socket of the bokeh blur filter that we looked at last time.

by default this will give you a pentagon shape, which you can adjust and tweak to your liking.

The Flaps slider corresponds to the number of flaps in your imaginary camera  aperture and it increases the number of sides on your bokeh shape.

this number goes from a simple three sided triangle to an almost perfect circle of twenty flaps.

The angle simply rotates the bokeh shape.

The Roundness slider bulges the edges of your shape to give you a more rounded appearance. you can adjust this from no roundness to a perfect circle.



Catadioptrics is a slightly weird setting. it refers to the effect that you get from certain lenses that have something blocking the front of the lens from letting light directly onto the sensor, such as a mirror, as an example, Youtuber Christopher Burress achieved this effect by connecting his sony A6500 to a telescope… check out his channel for lens reviews and other camera related stuff!


The final setting on this node is the lens shift, and all this does is to help approximate a bit of chromatic aberration in your bokeh. by increasing the value you can give a blue fringe to your shape, if you decrease the valueinto the negative numbers the shift will go towards the yellow and reds. If you are using the catadioptrics though, the inner circle will take on the shift opposite to the value you have chosen as you can see in the image below.

so that’s it, and obviously once you have the settings you like then you can adjust the values in the bokeh filter to get the perfect look for your scene. In this example, we cranked up the blur amount and raised the size of the bokeh to get a compley blurred image with some nice large bokeh shapes, ready for us to composite our foreground image over the top.


so thats it for the bokeh. but dont forget, this is still an image node so you can use this in any image input to give yourself a shape. ok maybe it doesnt sound useful but if you insert some keyframes you could use it as an animated mask for transitions and such like.

except it will eat your CPU, so bear that in mind when it comes to using this node 😉

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