Media type · image/jpeg
image/jpeg
image/jpeg is the media type for JPEG photographs and other lossy raster images.
Key facts
| Type | image/jpeg |
|---|---|
| Extensions | .jpg, .jpeg, .jpe |
| Standard | ISO/IEC 10918; JFIF |
| Text or binary | Binary |
| Transparency | No |
What image/jpeg is
JPEG is a lossy raster format tuned for photographs. It compresses well because it discards detail the eye is less likely to notice. The quality setting controls that trade-off: around 75–85 is usually visually indistinguishable from the original at normal viewing sizes, while smaller values produce visible blocking.
The image/jpg mistake
The registered type is image/jpeg. image/jpg is not registered; browsers often tolerate it, but strict clients and APIs may reject it. Use the file extension .jpg freely — extension and media type are different namespaces. JPEG has no alpha channel, so transparent areas become black or white depending on the encoder.
Frequently asked questions
Is image/jpg a real MIME type?
No. The registered type is image/jpeg. Some software accepts image/jpg, but it is not standard.
Does re-saving a JPEG reduce quality?
Yes. Each lossy re-encode discards more detail. Keep the original and encode once at the final size.