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The HDR Guide

What HDR actually means, how it differs from SDR, and how to tell a real HDR image from a fake one.

Color Spaces Explained

sRGB, Display P3, Rec. 2020 — what a color space actually controls, and which gamut your display can show.

Fundamentals

What Is HDR, Actually?

HDR without the jargon: what dynamic range means, and why it's not the same as your phone's HDR camera mode.

HDR vs. SDR

A side-by-side comparison: reference brightness, transfer functions, gamut, and what actually changes.

What's a Nit?

How screen and image brightness gets measured, with real reference points from starlight to daylight.

What Is Bit Depth?

8-bit vs. 10-bit: how many brightness levels a channel can store, and why gradients sometimes band.

What Is Tone Mapping?

The math that squeezes or stretches a scene's real brightness to fit whatever screen is showing it.

HDR standards

What Is PQ (SMPTE ST 2084)?

The Perceptual Quantizer transfer function behind most HDR video and images, and how it differs from gamma.

What Is HLG?

Hybrid Log-Gamma — the broadcast-friendly HDR transfer function built to look reasonable on SDR screens too.

What Is Rec. 2020?

The huge color gamut standardized for UHD television, and why almost no real display fully covers it.

What Is Rec. 2100?

The full HDR television standard — Rec. 2020 color plus the PQ or HLG transfer function that carries brightness.

What Is HDR10?

The open, royalty-free HDR standard almost every HDR TV and streaming service supports as a baseline.

What Is Dolby Vision?

The proprietary, dynamic-metadata HDR format built on PQ — and why it's mostly a video-pipeline concern.

What Is Display P3?

The wide-gamut color space behind most modern phone and monitor screens, and how it differs from sRGB.

What Is an ICC Profile?

What tells software exactly which colors an image's numbers actually mean — and why colors can look different.

HDR photo formats

What Is a Gain Map?

The trick behind most HDR photos you've actually seen — one file, two images, and a normal-looking fallback.

What Is Ultra HDR?

Google's gain-map-based HDR photo format, used by Android's camera and Google Photos — how it's structured.

HDR Image Formats, Honestly Compared

JPEG, PNG, WebP, AVIF, JPEG XL, HEIF — which actually support HDR today, and which we can encode locally.

Every guide, in one place