Format Support
This page details the image formats supported by @cross/image, their features, and runtime compatibility.
Format Support Matrix
This table shows which image formats are supported and their implementation status:
| Format | Read | Write | Pure-JS Decode | Pure-JS Encode | Native API Decode | Native API Encode | Notes |
|---|---|---|---|---|---|---|---|
| PNG | ✅ | ✅ | ✅ Full | ✅ Full | ✅ ImageDecoder | ✅ OffscreenCanvas | Complete pure-JS implementation |
| APNG | ✅ | ✅ | ✅ Full | ✅ Full | ✅ ImageDecoder | N/A | Animated PNG with multi-frame support |
| BMP | ✅ | ✅ | ✅ Full | ✅ Full | ✅ ImageDecoder | ✅ OffscreenCanvas | Complete pure-JS implementation |
| ICO | ✅ | ✅ | ✅ Full | ✅ Full | ✅ ImageDecoder | ✅ OffscreenCanvas | Windows Icon format |
| DNG | ✅ | ✅ | ✅ Full | ✅ Full | N/A | N/A | Linear DNG (Uncompressed RGBA) |
| PAM | ✅ | ✅ | ✅ Full | ✅ Full | N/A | N/A | Netpbm PAM (Portable Arbitrary Map) |
| PPM | ✅ | ✅ | ✅ Full | ✅ Full | N/A | N/A | Netpbm PPM (Portable PixMap) P3/P6 formats |
| PCX | ✅ | ✅ | ✅ Full | ✅ Full | N/A | N/A | ZSoft PCX (RLE compressed) |
| ASCII | ✅ | ✅ | ✅ Full | ✅ Full | N/A | N/A | Text-based ASCII art representation |
| JPEG | ✅ | ✅ | ⚠️ Baseline & Progressive | ⚠️ Baseline & Progressive | ✅ ImageDecoder | ✅ OffscreenCanvas | Pure-JS decode: baseline & progressive (spectral selection + successive approximation). Encode: baseline (native) + basic progressive (pure-JS) |
| GIF | ✅ | ✅ | ✅ Full | ✅ Full | ✅ ImageDecoder | ✅ OffscreenCanvas | Complete pure-JS implementation |
| WebP | ✅ | ✅ | ⚠️ Lossless | ⚠️ Quantized | ✅ ImageDecoder | ✅ OffscreenCanvas | Pure-JS VP8L with quality-based quantization |
| TIFF | ✅ | ✅ | ⚠️ Basic | ⚠️ Basic | ✅ ImageDecoder | ✅ OffscreenCanvas | Pure-JS for uncompressed, LZW, PackBits, Deflate; grayscale & RGB/RGBA |
| HEIC | ✅ | ✅ | ❌ | ❌ | ✅ ImageDecoder | ✅ OffscreenCanvas | Requires runtime API support |
| AVIF | ✅ | ✅ | ❌ | ❌ | ✅ ImageDecoder | ✅ OffscreenCanvas | Requires runtime API support |
Legend:
- ✅ Full support - Complete implementation with all common features
- ⚠️ Limited support - Partial implementation with restrictions
- ❌ Not supported - Feature not available in pure-JS, requires native APIs
- Pure-JS - Works in all JavaScript runtimes without native dependencies
- Native API - Uses runtime APIs like ImageDecoder (decode) or OffscreenCanvas (encode)
Format Specifications Supported
This table shows which format standards and variants are supported:
| Format | Specification/Variant | Support Level | Implementation |
|---|---|---|---|
| PNG | PNG 1.2 (ISO/IEC 15948) | ✅ Full | Pure-JS |
| - Interlaced (Adam7) | ❌ Not Yet | - | |
| - Color types: Grayscale, RGB, RGBA | ✅ Full | Pure-JS | |
| - Metadata: pHYs, tEXt, iTXt, eXIf | ✅ Full | Pure-JS | |
| APNG | APNG (Animated PNG) | ✅ Full | Pure-JS |
| - acTL, fcTL, fdAT chunks | ✅ Full | Pure-JS | |
| - Multi-frame animation decode | ✅ Full | Pure-JS | |
| - Multi-frame animation encode | ✅ Full | Pure-JS | |
| - Frame disposal methods | ✅ Full | Pure-JS | |
| - Metadata: pHYs, tEXt, iTXt, eXIf | ✅ Full | Pure-JS | |
| BMP | Windows BMP (BITMAPINFOHEADER) | ✅ Full | Pure-JS |
| - 24-bit RGB | ✅ Full | Pure-JS | |
| - 32-bit RGBA | ✅ Full | Pure-JS | |
| - Compressed variants (RLE) | ❌ Not Yet | - | |
| ICO | Windows Icon (ICO/CUR) | ✅ Full | Pure-JS |
| - Multi-image support | ✅ Full | Pure-JS | |
| - PNG-encoded images | ✅ Full | Pure-JS | |
| JPEG | JPEG/JFIF Baseline DCT | ✅ Full | Pure-JS |
| Progressive DCT (SOF2) | ✅ Full | Pure-JS | |
| - Spectral selection | ✅ Full | Pure-JS | |
| - Successive approximation | ✅ Full | Pure-JS | |
| - Progressive encoding (SOF2 output) | ⚠️ Basic | Pure-JS | |
| - EXIF metadata | ✅ Full | Pure-JS | |
| - JFIF (APP0) with DPI | ✅ Full | Pure-JS | |
| WebP | WebP Lossless (VP8L) | ⚠️ Basic | Pure-JS |
| - Simple Huffman coding | ✅ Full | Pure-JS | |
| - LZ77 backward references | ❌ Not in encoder | - | |
| - Color cache | ❌ Not in encoder | - | |
| - Transforms (predictor, etc.) | ❌ Not Yet | - | |
| WebP Lossy (VP8L with quantization) | ✅ Quality-based | Pure-JS | |
| - Color quantization for lossy | ✅ Full | Pure-JS | |
| WebP Lossy (VP8) | ⚠️ Native only | ImageDecoder | |
| - EXIF, XMP metadata | ✅ Full | Pure-JS | |
| TIFF | TIFF 6.0 - Uncompressed RGB/RGBA | ✅ Full | Pure-JS |
| TIFF 6.0 - LZW compressed RGB/RGBA | ✅ Full | Pure-JS | |
| TIFF 6.0 - PackBits compressed | ✅ Full | Pure-JS | |
| TIFF 6.0 - Deflate compressed | ✅ Full | Pure-JS | |
| TIFF 6.0 - Grayscale (0, 1) | ✅ Full | Pure-JS | |
| - JPEG compression | ⚠️ Native only | ImageDecoder | |
| - Multi-page/IFD (decode & encode) | ✅ Full | Pure-JS | |
| - EXIF, Artist, Copyright metadata | ✅ Full | Pure-JS | |
| GIF | GIF87a, GIF89a | ✅ Full | Pure-JS |
| - LZW compression/decompression | ✅ Full | Pure-JS | |
| - Color quantization (encoding) | ✅ Full | Pure-JS | |
| - Transparency support | ✅ Full | Pure-JS | |
| - Interlacing support | ✅ Full | Pure-JS | |
| - Animation (multi-frame decode) | ✅ Full | Pure-JS | |
| - Animation (multi-frame encode) | ✅ Full | Pure-JS | |
| - Comment extensions, XMP | ✅ Full | Pure-JS | |
| DNG | Adobe DNG 1.6.0.0 (Linear) | ✅ Full | Pure-JS |
| PAM | Netpbm PAM (Portable Arbitrary Map) | ✅ Full | Pure-JS |
| PPM | Netpbm PPM (Portable PixMap) | ✅ Full | Pure-JS |
| - P3 (ASCII) format | ✅ Full | Pure-JS | |
| - P6 (Binary) format | ✅ Full | Pure-JS | |
| - Comments in header | ✅ Full | Pure-JS | |
| - Maxval scaling (1-255) | ✅ Full | Pure-JS | |
| PCX | ZSoft PCX Version 5 (3.0) | ✅ Full | Pure-JS |
| - 24-bit RGB (3 planes) | ✅ Full | Pure-JS | |
| - 8-bit Palette (1 plane) | ✅ Decode only | Pure-JS | |
| ASCII | Text-based ASCII art | ✅ Full | Pure-JS |
| - Multiple character sets | ✅ Full | Pure-JS | |
| - Configurable width & aspect ratio | ✅ Full | Pure-JS | |
| - Brightness inversion | ✅ Full | Pure-JS | |
| HEIC | HEIC/HEIF (ISO BMFF) | ✅ Runtime only | ImageDecoder |
| - Brand: heic, heix, hevc, hevx | ✅ Full | ImageDecoder | |
| - Brand: mif1, msf1 | ✅ Full | ImageDecoder | |
| - EXIF metadata extraction | ✅ Full | Pure-JS | |
| AVIF | AVIF (AV1 Image File Format) | ✅ Runtime only | ImageDecoder |
| - Brand: avif, avis, avio | ✅ Full | ImageDecoder | |
| - EXIF metadata extraction | ✅ Full | Pure-JS |
Runtime Compatibility by Format
| Format | Deno 2.x | Node.js 18+ | Node.js 20+ | Bun | Notes |
|---|---|---|---|---|---|
| PNG | ✅ | ✅ | ✅ | ✅ | Pure-JS works everywhere |
| APNG | ✅ | ✅ | ✅ | ✅ | Pure-JS works everywhere |
| BMP | ✅ | ✅ | ✅ | ✅ | Pure-JS works everywhere |
| ICO | ✅ | ✅ | ✅ | ✅ | Pure-JS works everywhere |
| DNG | ✅ | ✅ | ✅ | ✅ | Pure-JS works everywhere |
| PAM | ✅ | ✅ | ✅ | ✅ | Pure-JS works everywhere |
| PPM | ✅ | ✅ | ✅ | ✅ | Pure-JS works everywhere |
| PCX | ✅ | ✅ | ✅ | ✅ | Pure-JS works everywhere |
| ASCII | ✅ | ✅ | ✅ | ✅ | Pure-JS works everywhere |
| GIF | ✅ | ✅ | ✅ | ✅ | Pure-JS works everywhere |
| JPEG | ✅ | ✅ | ✅ | ✅ | Pure-JS baseline & progressive DCT with spectral selection |
| WebP | ✅ | ⚠️ Lossless | ✅ | ✅ | Node 18: pure-JS lossless only, 20+: full |
| TIFF | ✅ | ✅ | ✅ | ✅ | Pure-JS uncompressed, LZW, PackBits, Deflate; grayscale & RGB/RGBA |
| HEIC | ✅ | ⚠️ Runtime | ✅ | ✅ | Requires ImageDecoder API support |
| AVIF | ✅ | ⚠️ Runtime | ✅ | ✅ | Requires ImageDecoder API support |
Note: For maximum compatibility across all runtimes, use PNG, APNG, BMP, ICO, GIF, ASCII, PCX, PPM or DNG formats which have complete pure-JS implementations.
Implementation Details
For detailed technical information about specific format implementations: