JPEG is a widely used photo format with lossy compression, developed in the 1990s, that greatly reduces image file sizes. It is well suited for the web, social media, and email, but is not ideal for intensive editing or repeated saving, since quality is lost each time the file is saved. The highest quality levels minimize artifacts such as blockiness and color fringing.
Category: Photography Basics > 6. Photo Formats & Files Article ID: 6.2 Created: May 2026
The Essentials at a Glance
- JPEG is the most widely used photo format – small, compatible, and ready to use
- JPEG uses lossy compression: image information is irreversibly lost each time the file is saved
- Ideal for: the web, social media, and email – not ideal for intensive editing or repeated saving
Explanation
What Is JPEG?
JPEG (Joint Photographic Experts Group) is a file format for digital photos – developed in the early 1990s by the Fraunhofer Institute. The file extension is .jpg or .jpeg.
Why was JPEG developed? Early digital cameras stored images without compression (bitmap format): A 2-megapixel photo took up approximately 6 MB – a problem at the time because memory cards held only 128–256 MB. JPEG solved this problem through drastic compression: the same image required only 250 KB–2 MB.
How Does JPEG Compression Work?
JPEG divides the image into 8×8-pixel blocks. Each block is mathematically simplified – fine details and subtle color transitions are reduced or removed in the process. In most cases, the human eye does not notice this simplification.
Result: When an image is saved as a JPEG, information is irreversibly lost – the original cannot be restored.
JPEG Quality Levels
The strength of the compression can be adjusted – most cameras and programs offer quality levels:
| Quality level | File size | Visible artifacts | Typical use |
|---|---|---|---|
| Low | Very small | Distinct (blockiness) | Web thumbnails, preview images |
| Medium | Medium | Barely visible | General use, web |
| High | Larger | Only at high magnification | Printing, archiving |
| Super Fine | Large | Virtually none | Professional use |
The JPEG Quality Problem: Generation Loss
Every time a JPEG image is opened, edited, and saved again, additional quality loss occurs. After multiple saves, the quality can become noticeably worse.
Solution: Always edit photos in a lossless format (TIFF, RAW) or as a Smart Object – save as a JPEG only when exporting the final version.
Typical JPEG Artifacts
When compression is too strong, visible distortions appear:
- Blockiness: The image appears to be divided into 8×8-pixel blocks
- Color fringing (ringing): Bright edges are surrounded by dark borders
- Color bleeding: Saturated colors bleed into adjacent areas
These artifacts occur particularly along high-contrast edges (e.g., text, sharp lines) and are barely visible at high JPEG quality.
When Is JPEG the Right Choice?
JPEG is ideal for:
- Web photos, social media, and email
- Photos with no intensive editing planned
- Everyday shots, snapshots
- When file size matters
JPEG is not ideal for:
- Intensive editing (→ preferably RAW or TIFF)
- Photos that will be saved/edited multiple times
- Professional print production
- Archiving original images
Practical Tip
Anyone who relies on JPEG in their camera should choose the highest quality level (Super Fine or Fine). The difference in file size is negligible with modern memory cards, but the difference in quality is significant – especially if the image may later need to be edited after all. Also: Never save JPEG images multiple times – keep the original and export only copies.