The best image compression starts with the right dimensions and format, then lowers quality only as far as the real viewing size allows. The goal is not the smallest possible file; it is the smallest acceptable file for its use.
Start with display dimensions
A 4,000-pixel-wide camera photo is unnecessary in a 1,200-pixel-wide article column. Resize oversized images before aggressively lowering quality. Fewer pixels often save more space with less visible damage.
Choose a format that matches the image
| Image type | Good starting format | Reason |
|---|---|---|
| Photograph | WebP or JPEG | Efficient lossy compression for continuous colour |
| Screenshot with text | PNG or lossless WebP | Keeps edges and small text clearer |
| Transparent graphic | WebP or PNG | Supports transparent areas |
| Simple logo or icon | Original vector when available | Scales cleanly without raster pixels |
A practical compression workflow
- Keep an untouched copy of the original.
- Crop away unused edges and resize to the largest needed display size.
- Choose the output format based on photo, text, transparency, and compatibility needs.
- Start with a moderate quality setting and download a test.
- Compare the result at its actual display size, then lower quality gradually if needed.
Where compression damage appears first
- Small text and sharp interface details.
- High-contrast edges around products or logos.
- Smooth gradients such as skies, shadows, and studio backgrounds.
- Fine textures including hair, fabric, grass, and foliage.
Avoid repeated lossy exports
Reopening and recompressing an already compressed JPEG or WebP can add new artifacts. Return to the original whenever you need a different size or quality level, and create each delivery version from that source.
Privacy and format reference
Entwicklera's image compression runs locally in your browser and creates a local download. For a deeper comparison of JPEG, PNG, WebP, AVIF, and other web formats, see MDN's image file type guide.