HDR
HDR (High Dynamic Range)
An imaging technique that captures or represents a wider range of brightness levels than standard images, preserving detail in both the darkest shadows and brightest highlights of a scene.
技術的詳細
Standard Dynamic Range (SDR) images use 8 bits per channel (256 levels), while HDR uses 10-bit (1,024), 12-bit (4,096), or floating-point representations. HDR image formats include OpenEXR (ILM standard, 16/32-bit float), Radiance HDR (.hdr, RGBE encoding), AVIF (10/12-bit HDR support), and JPEG XL (lossless HDR). Tone mapping algorithms compress HDR data into SDR displays' limited brightness range. Modern displays (HDR10, Dolby Vision) can render HDR content directly with peak brightness exceeding 1,000 nits, compared to SDR's ~100-300 nits.
例
```javascript
// HDR: processing with Canvas API
const canvas = document.createElement('canvas');
const ctx = canvas.getContext('2d');
ctx.drawImage(sourceImage, 0, 0);
const imageData = ctx.getImageData(0, 0, canvas.width, canvas.height);
// Process pixels in imageData.data (RGBA array)
```