Bloom

The Bloom effect creates fringes of light extending from the borders of bright areas in an image, contributing to the illusion of an extremely bright light overwhelming the Camera.

You can also use Lens Dirt to apply a full-screen layer of smudges or dust to diffract the Bloom effect.

Properties

Bloom settings:

Property	Function
Intensity	Set the strength of the Bloom filter.
Threshold	Set the level of brightness to filter out pixels under this level. This value is expressed in gamma-space.
Soft Knee	Set the gradual threshold for transitions between under/over-threshold (0 = hard threshold, 1 = soft threshold).
Clamp	Set the value for clamping pixels to control the Bloom amount. This value is expressed in gamma-space.
Diffusion	Set the extent of veiling effects in a screen resolution-independent fashion.
Anamorphic Ratio	Set the ratio to scale the Bloom vertically (in range [-1,0]) or horizontally (in range [0,1]). This emulates the effect of an anamorphic lens.
Color	Select the color of the tint of the Bloom filter.
Fast Mode	Enable this checkbox to boost performance by lowering the Bloom effect quality.

Dirtiness settings:

Property	Function
Texture	Select a Dirtiness texture to add smudges or dust to the lens.
Intensity	Set the amount of lens dirtiness.

Details

With properly exposed HDR scenes, the Threshold should be set to ~1 so that only pixels with values above 1 leak into surrounding objects. Drop this value when working in LDR or the effect won’t be visible.

Performance

Lowering the Diffusion parameter will make the effect faster. The further away Anamorphic Ratio is from 0, the slower it will be. Enable Fast Mode if you are developing for mobile or low-end platforms to get a significant boost in performance.

Smaller lens dirt textures will result in faster lookup and blending across volumes.

Requirements

• Shader model 3

See the Graphics Hardware Capabilities and Emulation page for further details and a list of compliant hardware.