CG Education

Specular Bloom (also called Diffuse Glow, Bloom, Glow, Ghosts, Flare, Glares) is what we call it when the bright objects in your scene glow.

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Photoshop

Using a program such as photoshop to do your glows can be a much faster way than doing it from inside 3dsmax, since you never need to rerender your 3d element. The general procedure is as follows...

Take your image, duplicate the image as a layer



Heighten the contrast and reduce the brightness to get just an image that only represents the bright parts of your image (for my test I changed the brightness to -30 and the contrast to 90)



Desaturate the layer (you can experiment with only desaturating it slightly or modifying the hue of this image to achieve colored glows)



Blur it with a "Gaussian Blur" filter (for this test, I used a value of 15)



Note: You can also experiment with the "Lens Blur" filter instead of the "Gaussian Blur", which will give you a more defined defocusing effect similar to a Bokeh effect.

Then set the mode of the layer to linear dodge (this is an additive blend, see my Photoshop Tips lesson for more discussion on linear dodge and it's relation to an additive mode). Now your have a glow layer sitting on top of your original image. Playing with the layer's Opacity controls how much of the glow is mixed with the original image.



Here's what the layers look like for this effect...



And here's an experiment with adding color to the blurred layer...

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