The Add Bloom Output AOV node can be used to add a halo around the sun, light source, or reflective material.of a composite or components of a composite node tree (figure 1).


Add Bloom

Figure 1: The Add Bloom Output AOV node used to add a bloom or halo effect to a composite node tree


Add Bloom Parameters

Enabled - Determines whether the effect is active or not.

Strength - The amount of bloom to apply. 0% means no bloom and 100% means the maximum bloom possible given the spread start and spread end values. 

Spread Start - The minimum blur radius, as a proportion of image width or height (whichever is larger).

Spread End - The maximum blur radius, as a proportion of image width or height (whichever is larger).

Colorize Strength - The strength with which to apply a rainbow-style color effect to the bloom.

Colorize Phase - Determines the hue of the colorize effect.