Informazioni sui file JPEG

JPEG (JPEG Image · Formato immagine)

Rilasciato 1992 Di Joint Photographic Experts Group (ISO/IEC & ITU-T)

JPEG Image (.jpeg) è un formato di file standard supportato da KaijuConverter per l’archiviazione, la condivisione e la conversione multipiattaforma.

Famiglia

Raster & Vector Images

Estensione

.jpeg

Tipo MIME

image/jpeg

Utilizzabile come

Input

La storia

COME JPEG
È NATO.

1986

1992

JPEG stands for Joint Photographic Experts Group — the name of the committee, not the file. Formed in 1986 as a joint working group between ISO and ITU-T, it drafted a compression standard specifically for continuous-tone photographs. The final JPEG spec (ITU-T T.81) was published in 1992.

The trick that made JPEG win: discrete cosine transform (DCT). The algorithm divides an image into 8×8 blocks, converts each to frequency space, and aggressively discards high-frequency details the human eye barely notices. A decade later the web explosion turned JPEG into the default currency of digital photography. Despite being over 30 years old and technically outclassed by WebP, AVIF and JPEG XL, JPEG still accounts for roughly 75% of all images served on the open web — a testament to universal support trumping pure compression math.

CURIOSITÀ E
ANEDDOTI.

The official pronunciation is "JAY-peg" — confirmed by the committee itself. "JIFF" vs "GIF" is a different religious war.

JPEG was designed before the web existed — the committee was thinking about digital cameras and storage.

Progressive JPEGs load in successive passes (blurry → sharp). They were invented for slow dial-up modems and are still useful on 3G.

The default quality level in Photoshop is "12" (equivalent to ~92%). Below 85% most viewers start seeing artifacts.

A single JPEG can carry EXIF metadata, XMP, IPTC, and even a tiny embedded thumbnail — all in the same file.

PUNTI DI FORZA E
LIMITAZIONI.

Punti di forza

Universally supported — every camera, browser, OS, and editor reads JPEG.
Mature, deterministic, and fast to encode/decode.
Small file sizes for photographs — DCT compression shines on continuous-tone imagery.
Rich metadata ecosystem (EXIF for shooting data, XMP for editing, IPTC for captions).
Progressive variant enables perceived faster loading on slow networks.

Limitazioni

Lossy by design — every save further degrades quality ("generation loss").
No transparency channel. Logos and UI elements belong in PNG or WebP.
Terrible on flat colors, text, and sharp edges — blocking artifacts are visible.
Limited to 8-bit color — HDR and wide gamut need JPEG XL or AVIF.
Twice the size of WebP and 30-50% bigger than AVIF at comparable quality.

Dimensioni e pesi tipici

Thumbnail (400px)

20-60 KB

Web photo (1920px)

200-500 KB

Print-quality photo (3000px)

1-4 MB

DSLR JPEG (24 MP, quality 95)

6-12 MB

Specifiche tecniche

MIME type: image/jpeg
File extensions: .jpg, .jpeg, .jpe, .jfif
Standard: ITU-T T.81 / ISO/IEC 10918-1:1994
Compression: Lossy DCT (baseline); lossless mode exists but rarely used
Color depth: 8-bit per channel (24-bit RGB total)
Max dimensions: 65 535 × 65 535 px

CONVERTI DA
JPEG

jpeg jpg jpeg png jpeg webp jpeg avif jpeg gif jpeg bmp jpeg tiff jpeg ico jpeg svg jpeg pdf

Casi d'uso comuni

Legacy camera output, cross-platform compatibility.