Bloom extracts pixels exceeding a specified luminance threshold, blurs them, and composites the result back over the frame using additive blending. It is commonly used to produce halos around emissive surfaces, bright specular highlights, and neon lighting.
OriginalEffectControls
| Control | Range | Default | Effect |
|---|---|---|---|
| Bloom Type | Normal / Streak / Star | Normal | Soft omnidirectional halo, horizontal streaks, or star rays |
| Intensity | 0 – 10 | 0.1 | Brightness boost added back to the frame (~1 is typically quite bright) |
| Threshold | 0 – 5 | 0.75 | Minimum brightness required to trigger bloom; areas brighter than this will glow |
| Threshold Smoothness | 0 – 1 | 0 | Softness of the transition around the threshold cutoff (soft knee) |
| Radius | 0 – 6 | 3 | Spread radius of the diffused glow |
| Saturation | −1 – 1 | 0 | Color saturation of the generated glow |
| Color | Hex | #ffffff | Color tint applied to the bloom highlights |
| Opacity | 0 – 1 | 1 | Blend opacity of the bloom pass over the frame |
Bloom operates additively and only brightens the image. If no pixels in a frame exceed the threshold, the rendered output remains completely identical whether bloom is enabled or disabled.
Bloom Type
Normal: Produces a soft, diffuse glow that spreads naturally outward from bright areas, well suited for most scenes.
Streak: Simulates the horizontal lens flare characteristic of anamorphic lenses, stretching highlights horizontally into bright light bars.
Star: Simulates the diffraction spikes produced by lens aperture blades, scattering light rays outward in multiple directions. Enabling Star mode displays two additional controls:
| Control | Range | Default | Effect |
|---|---|---|---|
| Star Rays | 1 – 6 | 3 | Number of diffraction ray axes |
| Star Angle | 0 – 360° | 0° | Rotational angle of the starburst pattern |
Threshold
The default threshold of 0.75 targets prominent specular highlights and emissive surfaces. Lowering the threshold includes dimmer areas in the bloom calculation; approaching 0 causes broad surfaces such as character faces to glow.
Threshold Smoothness controls the transition curve around the threshold cutoff point. At 0, a hard cutoff applies — pixels exceeding the threshold glow immediately at full intensity, which can introduce abrupt boundaries or flickering during movement; increasing the value introduces a gentle ramp that stabilizes luminance changes smoothly.
The MToon Emissive multiplier for VRM models scales up to ×4, enabling specific materials to easily surpass the bloom threshold. Pair these controls to create glowing eyes or illuminated cyber visors.
Glowing Only Selected Colors
These controls appear only when bloom is used as a layer effect. Scene-level bloom does not include color filtering.
By default, any pixel exceeding the brightness threshold generates bloom. Enabling Select Colors restricts the glow exclusively to pixels matching designated hues — ideal for isolating neon signs, glowing irises, or specific accessories.
Five independent color channels can be configured through the Color Slot selector: choose a slot to adjust its toggle and target color.
| Control | Range | Default | Effect |
|---|---|---|---|
| Select Colors | Switch | Off | Restricts bloom generation to selected colors |
| Invert Selection | Switch | Off | Inverts the filter to glow all unselected colors |
| Color Tolerance | 0.01 – 1 | 0.5 | Allowed deviation across hue, saturation, and luminance |
| Color 1 – 5 | Hex | #ffffff | Target color values eligible for bloom |
| Use Color 1 – 5 | Switch | Slot 1 only (on) | Whether this slot participates in color matching |
Color 1 is enabled by default: if all five slots are disabled, the matching mask is empty, causing Select Colors to eliminate all bloom rather than restricting its range.
Increasing Color Tolerance expands the acceptance radius to include neighboring shades with minor saturation and brightness differences; setting it to the minimum requires an exact color match.
Processing Order
Bloom runs after chromatic aberration and before diffusion, allowing subsequent diffusion passes to soften the generated bloom highlights.
Last updated on November 3, 2026