What it does
Makes bright areas bloom with soft halos, like lights glowing through a hazy lens.
Bloom is an artifact before it is an effect. Light scatters inside lens glass, diffracts through the aperture, and bleeds between photosites on a sensor, so any sufficiently bright source smears a veil of light around itself. Eyes do it too, which is why headlights halo at night. Rendering borrowed the artifact for a practical reason: a screen cannot show anything brighter than white, so the halo became the standard cue that a pixel is far past white. When something glows, you read it as luminous rather than merely pale.
The difference between glow that reads as light and glow that reads as haze comes down to two decisions most filters get wrong. Blurring in the gamma-encoded image dims and muddies the falloff, because the math is averaging display values rather than light; convincing bloom blurs in linear light, where energy adds the way photons do. And a single blur size cannot describe scattered light, which has a tight hot core and a very long soft tail at the same time. The technique modern game engines settled on sums a whole pyramid of blur scales, from fine to frame-wide, and Modulate’s Glow is built exactly that way.
In use, the craft is in what gets to glow. A high threshold lifts only the speculars and light sources, which is how restrained cinematic bloom works; a low one pulls the whole frame into radiance, the diffusion-filter look of dream sequences and music videos. The halo can be tinted, pushed from a few-pixel rim to a wash that crosses the frame, and driven hard enough that cores blow out to clean white, which is correct behavior for light. The glow also escapes the silhouette of transparent layers, so type and cutouts can halo onto nothing.
Signature looks
Neon night
Signage and city lights flaring into tinted halos against the dark. The cores stay hot and crisp while the spill runs long and soft.
Dream haze
The whole frame lifted into a soft radiance, highlights melting outward. The diffusion-filter look of memory sequences and slow songs.
Glowing type
Bright lettering bleeding light past its own edges onto a dark ground, neon signage without the glass tubes.
Try it on your own footage
This effect runs live in the Modulate editor, with layers, effect chains, masks, and keyframes. Free, no signup, nothing to install.
Common questions
What is the bloom effect?
Bloom is the fringe of light that spreads around very bright areas of an image, imitating what strong light does inside real lenses, sensors, and eyes. Digitally it is produced by isolating pixels above a brightness threshold, blurring them, and adding the result back over the image. Games and film rendering lean on it because a display cannot exceed white, so the halo is what tells you a light source is intensely bright rather than just light gray.
Are glow and bloom the same effect?
Effectively yes. Photographers and colorists tend to say glow or halation, real-time rendering says bloom, and editors name the tool either way. All of them describe the same phenomenon: bright regions bleeding light past their edges. The quality bar is also shared, since a glow only reads as light when its falloff behaves like scattered light instead of a flat blur.
Why does a cheap glow effect look muddy?
Two reasons. Most filters blur the gamma-encoded image, which averages display values instead of light energy, so the halo goes dim and gray as it falls off. And most use a single blur radius, which can produce a tight rim or a wide wash but never both, while real scattered light has a hot core and a long tail simultaneously. Bloom done properly works in linear light and sums many blur scales, which is why good glow looks luminous all the way through its falloff.
Should everything glow, or only the highlights?
Both are legitimate looks with different jobs. Gating the glow to just the brightest speculars and sources keeps the image grounded and reads as cinematography. Letting the midtones bloom too turns the whole frame soft and radiant, which is a stylistic statement, the classic dream or flashback treatment. The threshold between them is the single most expressive decision in the effect.
Can you add a glow effect to video?
Yes. Glow is computed fresh for every frame from that frame’s brightness, so it tracks moving lights naturally, flaring and settling as sources enter and leave. In Modulate the Glow effect runs live on images and video in the browser, and stacks with grain, vignettes, and color adjustments in the editor.
Related effects
Star glow effect
Turns bright points into star glints with radiating rays and a hot glowing core, like a cross-screen filter on a lens.
Lens blur
Blurs like a real camera lens, with out-of-focus highlights blooming into soft bokeh shapes.
Threshold effect
Reduces the image to two colors with a hard cutoff between light and dark, with optional outlined edges.
CRT effect
The look of an old tube monitor: glowing phosphor stripes, slight color fringing, and a darkened vignette.