Quick answer

JPEG is a compressed raster image format commonly used for photographs. Its lossy compression can create small files, but repeated or aggressive compression can remove visible detail.

Original example

A photograph and a diagram

A JPEG export can reduce a photograph efficiently because nearby tones often vary gradually. The same setting may create halos and smudged edges around text in a sharp diagram.

When JPEG fits

JPEG is broadly supported and works well for continuous-tone still images. It does not provide an alpha transparency channel.

Keep an editable original before repeated exports. Each lossy re-encoding can introduce additional changes.

Common misunderstandings

  • The .jpg and .jpeg extensions commonly refer to the same format family.
  • JPEG is not always the smallest or best format for every image.

Related answers

Sources

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