Post
Rendering light values beyond the normal range, then letting the brightest parts glow and bleed into surrounding pixels.
High Dynamic Range rendering means calculating light values that exceed the standard 0-to-1 range, allowing the engine to represent the true difference between a dim room and blinding sunlight. Tone mapping then compresses this range for your display. Bloom is a post-processing effect that makes bright areas glow by bleeding light into neighboring pixels, simulating how real cameras and eyes perceive very bright light sources. On HDR displays, games can actually show those extreme brightness differences rather than just simulating them, with specular highlights that genuinely pop off the screen.
Example
Gran Turismo 7 is one of the best HDR showcases on PS5, with car paint and track lighting that look genuinely three-dimensional on an HDR TV. Doom Eternal uses bloom aggressively on its weapon effects and demonic portals to create a hellish, oversaturated atmosphere. The bloom in early 2000s games like Oblivion was notoriously overdone, giving everything an ethereal vaseline-on-the-lens look that became a meme.
Why it matters
HDR on a capable display is one of the biggest visual leaps in gaming, often more impactful than resolution bumps. Bloom, when used tastefully, adds atmosphere and sells the illusion of bright light sources. Together they make the difference between a game that looks flat and one that feels like looking through a window into another world.
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