Image Quality
Simple Gal encodes all output images -- responsive sizes and thumbnails -- in AVIF format. The quality setting controls the tradeoff between file size and visual fidelity.
Configuration
[images]
quality = 90
The value is an integer from 0 to 100. Higher values produce larger files with fewer compression artifacts. Lower values produce smaller files with more visible degradation.
Choosing a quality value
The default of 90 is a good starting point for fine art photography. At this level, compression artifacts are invisible at normal viewing distances, and the files are roughly half the size of equivalent JPEGs.
| Quality | Use case | Notes |
|---|---|---|
| 95-100 | Archival, print-resolution work | Minimal compression. Large files. Diminishing returns above 95. |
| 85-90 | Portfolio display (default range) | Visually lossless for web viewing. Good balance. |
| 70-80 | Documentation, travel snapshots | Noticeable softening on close inspection. Significantly smaller files. |
| Below 70 | Not recommended | Visible artifacts, especially in gradients and fine detail. |
For most photography portfolios, values between 85 and 90 are the sweet spot. Going above 90 increases file size substantially with no perceptible improvement on screen.
AVIF vs JPEG
AVIF achieves better compression than JPEG at the same visual quality. As a rough guide:
- AVIF quality 90 is comparable to JPEG quality 95 in perceived sharpness
- AVIF files at quality 90 are typically 40-60% smaller than the equivalent JPEG
Simple Gal uses the rav1e encoder, a pure Rust AV1 implementation. This means no system dependencies -- the encoder is built into the binary. The tradeoff is that encoding is slower than hardware-accelerated alternatives, but this is offset by parallel processing across CPU cores.
Per-gallery overrides
Quality can be overridden at any level of the config chain. A gallery of phone snapshots might use a lower quality to reduce output size:
# content/030-Snapshots/config.toml
[images]
quality = 75
This gallery uses quality 75 while other galleries inherit the root config's quality 90. The quality setting applies to both responsive images and thumbnails for that gallery.
File size impact
To give a sense of scale, here are approximate file sizes for a single 2080px-wide landscape image at different quality levels:
| Quality | Approximate size |
|---|---|
| 100 | 800-1200 KB |
| 90 | 200-400 KB |
| 80 | 100-200 KB |
| 70 | 60-120 KB |
Actual sizes vary with image content. Images with smooth gradients (skies, studio backdrops) compress better than images with fine detail (foliage, textured surfaces).