Camera Image File Format

» see ciff-forum.com as it lived, on the wayback machine

~ the goodbye ~

The Camera Image File Format specification was published on 12 February 1997, which puts it three years ahead of the first camera that would ever write a file in it. It came in two documents, one describing the image data file and one describing how files and directories were organized on the card, and the second of those stopped being revised on 9 February 1998. Canon wrote it and maintained it, with input from an industry body called the CIFF Forum.

In practice CIFF was the thing inside a .crw file. Every Canon DSLR from the EOS D30 in 2000 through to the 300D wrote its raw files in it, as did the PowerShot Pro1 and the G-series compacts. If you shot raw on a Canon in the first four years of the century, this was the container your photograph was sitting in.

Then Canon built a new one. CR2 was based on TIFF, which meant it inherited a tag structure that other software already knew how to walk, and it arrived with the EOS-1D Mark II in 2004. The last cameras to write CRW were compacts announced the same year. There was no deprecation notice and no sunset date. A new body shipped, the extension on the memory card changed, and that was the entire funeral.

~ the chronicle ~

~ the container trick ~

CIFF had a second job almost nobody noticed. Canon also used it as a metadata container stuffed into the APP0 segment of ordinary JPEG files, which is the slot where a JPEG normally keeps its JFIF header. So a plain camera JPEG off a Canon could be carrying a block of CIFF structure around with it, invisible unless you went looking, which is why ExifTool still carries parsing code named after a format nobody has written to in two decades.

~ the committee and its domain ~

The CIFF Forum is the ghost in this story. Its website answered at ciff-forum.com from April 1999 and served the same 420-byte page every time the crawler came by, right up to January 2002, and then the captures stop. By 2020 the domain was answering with a Chinese content farm, several thousand bytes of auto-generated pages under directory names like 651zsd. The specification PDF itself was last hosted on a personal site at xyrion.org and now exists only as an archived file.

~ what still reads it ~

CRW is in better shape than most dead formats, because free software kept reading it. ExifTool and dcraw both handle it, and so does every raw developer built on top of LibRaw, which means a photograph taken on an EOS D30 in 2001 can still be decoded on a laptop in 2026 by code whose authors reverse-engineered the parts Canon never documented.

I never wrote a single file in this format. In 2001 I was on a 33.6k modem in Turkey and a raw frame off an early Canon ran to several megabytes, which is twenty minutes of a phone line you were sharing with the household. The whole first era of digital raw photography happened at a file size my connection treated as an insult, and by the time broadband arrived at my desk around 2006 Canon had already moved everybody to CR2.

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