JFIF

File Format
Name	JFIF
Ontology	Electronic File Formats Graphics JFIF
Extension(s)	.jpg .jpeg .jpe .jfif .jfi
MIME Type(s)	image/jpeg
PRONOM	fmt/44

Overview

JFIF (JPEG File Interchange Format) is a standard that defines a portable subset of the JPEG interchange format. Most of the JPEG files in existence conform to JFIF.

JFIF defines JPEG application segments which serve to identify JFIF files, and to store a small amount of metadata: the pixel density, and a thumbnail image.

The presence of a JFIF segment implies that:

• If the image has three components, its color format is YCbCr. If it has one component, its color format is grayscale.
• The image has a particular orientation.
• If the image is subsampled, it uses a particular subsampling position.

Identification

Valid JFIF files begin with FF D8 FF E0 ?? ?? 'J' 'F' 'I' 'F' 00. Some technically-invalid files exist in which the JFIF segment has been relocated, and for them this signature will not match.

History

• JFIF 1.00 (PRONOM: fmt/42) was the original version.

• JFIF 1.01 (December 10, 1991; PRONOM: fmt/43) may have changed the subsampling position to centered.

• JFIF 1.02 (September 1, 1992; PRONOM: fmt/44) added an optional JFXX segment, capable of storing a compressed thumbnail image.

Specifications

• JFIF version 1.01
• JFIF version 1.02
• ITU Recommendation T.871