JPG

Generated by scripts/gen-format-pages.py from docs/data/format-metadata/, FILE_FORMATS.csv and docs/formats-master.csv. Do not edit by hand: change the source, then run the script.

JPEG Markers Preview.

At a glance


Original creator	The Joint Photographic Experts Group (ISO/IEC JTC 1/SC 29/WG 10), with the ITU-T
First published	1992
Purpose	The same JPEG files as the JPEG entry, listed under the .jpg spelling.
Extensions	`.jpg`, `.jpeg`
Poka parser	`poka-jpeg`
Viewer	`poka-image-with-meta-viewer`
Depth tier	Parser with a shared viewer (see Depth tiers)
Breadth tier	B2 Broad (see Breadth tiers)

How much Poka reads

B2 Broad. The common content of the current and the common older versions is decoded. Some named features or versions are not, and are listed.

Confidence: medium (the reviewer read the code). Basis: Reviewed 2026-10-16: the .jpg spelling of the JPEG entry, served by the same crate (parsers/poka-jpeg plugin.json file_extension .jpg, alias .jpeg), so the tier and evidence are identical to JPEG: lib.rs, meta.rs, unit tests, tests/samples.rs, corpus SOF scan. Pixels are decoded in the module (#451).

What Poka does not read

12-bit, lossless, arithmetic-coded and differential modes are drawn only if zune-jpeg decodes them
EXIF limited to about 30 tags (no flash, metering, MakerNote, thumbnail); GPS position, artist, owner, serial numbers and user comment are among them and are always shown
UserComment in the JIS character code is named but not converted
XMP and IPTC contents not decoded (flagged present)
ICC profile name only
files whose decode would pass the decode budget get header facts only, no picture

Background

FILE_FORMATS.csv has two rows for JPEG, both served by poka-jpeg for .jpg and .jpeg; see the JPEG page for the history and what Poka draws. Poka reports the marker segments up to the frame header (the "JPEG Markers" in this row's description) and decodes the pixels in the module.

Libraries

Libraries Poka uses or has assessed for this format, with the status, licence and language the registry records.

zune-jpeg (candidate; MIT OR Apache-2.0 OR Zlib; Rust; https://github.com/etemesi254/zune-image)
jpeg-decoder (candidate; MIT OR Apache-2.0; Rust; https://github.com/image-rs/jpeg-decoder)
image (candidate; MIT OR Apache-2.0; Rust; https://github.com/image-rs/image)
ITU-T T.81 (JPEG) (candidate; public spec; spec; https://www.w3.org/Graphics/JPEG/itu-t81.pdf)

Sources

https://loc.gov/preservation/digital/formats/fdd/fdd000017.shtml
parsers/poka-jpeg/src/lib.rs