File compression is how your camera — or editing app — shrinks image file size to make photos easier to store, upload, and share. There are two main types:
- Lossy compression: permanently removes data to shrink file size (e.g., JPG, WebP)
- Lossless compression: reduces file size without deleting any image data (e.g., PNG, some RAW formats)
Most everyday photos — especially from smartphones — use lossy formats like JPG to save space. But every time you save or resave a JPG, it loses a little more data. Over time, this can create visible issues like:
- Blocky or smeared areas
- Reduced sharpness
- Color banding in gradients
RAW files, on the other hand, store the full sensor data with no loss — but they’re much larger and require special software to open or edit.
Choosing the right format depends on your goal:
- Sharing online: JPG or WebP at medium-high quality is usually fine
- Archiving originals: Use RAW or PNG to preserve detail
- Editing repeatedly: Avoid re-saving in JPG between steps
Compression isn't bad — it’s essential — but knowing when and how it’s used gives you control over quality and file size.