Format Parameters¶
fm - Format Conversion¶
The fm parameter is used to convert the image to a specified format. The following image formats are supported:
- JPEG - Universal compatibility, excellent for photographs
- PNG - Transparency support, ideal for graphics with alpha channel
- GIF - Animation support, legacy format
- WebP - Modern format with superior compression
- AVIF - Next-generation format with excellent compression
- JXL - JPEG XL format for advanced compression
q - Output Quality¶
The q parameter controls the output quality of the image for lossy formats, including JPEG, WebP, AVIF, and JXL.
Type: integer or string
Range: 0 - 100 or quality strings
Default: 75 (or 45 with Save-Data client hint)
Quality Values¶
- 0-30: Low quality, smallest file size
- 30-60: Medium quality, balanced size/quality
- 60-85: High quality, larger file size
- 85-100: Maximum quality, largest file size
Quality Strings¶
The following quality strings are supported for automatic quality optimization:
auto- Automatic quality selectionauto:high- High quality automatic selectionauto:med- Medium quality automatic selectionauto:low- Low quality automatic selection
Usage¶
Format Conversion¶
Convert JPEG to WebP format.Quality Control¶
High quality JPEG output.Automatic Quality¶
Automatic quality optimization using the machine-learning quality predictor. The optimiser inspects the source image and selects the lowest acceptable quality setting within the requested band (auto, auto:low, auto:med, auto:high) to balance fidelity and byte size.
Next-Generation Formats¶
Convert to AVIF with 75% quality.Format Guide¶
JPEG¶
- Best for: Photographs, complex images
- Compression: Lossy
- Transparency: No
- Browser support: Universal
PNG¶
- Best for: Graphics, logos, transparency needed
- Compression: Lossless
- Transparency: Yes
- Browser support: Universal
WebP¶
- Best for: Web optimization, modern browsers
- Compression: Lossy/Lossless
- Transparency: Yes
- Browser support: Modern browsers (95%+)
AVIF¶
- Best for: Maximum compression efficiency
- Compression: Lossy/Lossless
- Transparency: Yes
- Browser support: Growing (80%+)
JXL (JPEG XL)¶
- Best for: Future-proof high efficiency
- Compression: Superior lossy/lossless
- Transparency: Yes
- Browser support: Limited (experimental)