Exploring EXIF (2023)

My favourite thing about EXIF is its role in Hollywood and the news, e.g. "The geolocation from the metadata of this image verifies that this happened at this place and at this time", and other such nonsense nonsense. Always makes me chuckle.

My least favourite thing is colour profiles and how those can confuse grown adults and bring them to tears.

Fun fact: EXIF is simultaneously JPEG format (EXIF spec describes compressed image file format which is based on JIF, the base JPEG file format described in JPEG spec, also EXIF is for "EXchangeable Image File format", suggesting that authors saw it as new file format) and TIFF format (EXIF metadata is actually embedded TIFF which can be parsed with tiffdump, also EXIF spec describes uncompressed image file formats which are TIFF with embedded EXIF metadata which is also TIFF...)

Exif data is really fascinating, and exiftool is really worth playing around with for an afternoon. The metadata on color space, focal distance, aperture are all really useful tools for making photos look correct on an arbitrary display surface, and it is pretty fun to swap them out to see the effects on rendering.

As an aside, the location/time data is useful for somethings but also kind of creepy and I really wish there were more privacy considerations in how these pieces of meta data are handled. There was a period where I routinely set these fields to be taken in Pyongyang, North Korea, 100m below sea level and one day in the future.

exiftool -GPSLatitude=39.0738-GPSLatitudeRef=N -GPSLongitude=125.8198 -GPSLongitudeRef=E -GPSAltitude=-6 -GPSAltitudeRef="Below Sea Level" -AllDates="$(date -v +1d '+%Y-%m-%d %H:%M:%S')" FILENAME.jpg

Discussed at the time:

Exploring EXIF - https://news.ycombinator.com/item?id=37409524 - Sept 2023 (33 comments)