EXIF data

Your photo files actually contain hidden information. EXIF stands for Exchangeable Image File Format, and is a standard for storing interchange information in image files, especially those using JPEG compression. Most digital cameras now use the EXIF format to ecord of the settings a camera used to take a photo or video. This information is embedded into the files the camera saves.

Most of it is pretty innocuous but not all. EXIF data includes the date and time the photo was taken. The model and serial number of the camera are recorded. And depending on the camera, the settings you used may also be stored.

Keep in mind that some smartphones store the location where the picture is taken to the picture EXIF data. This can be a good or bad depending how sensitive the location information is and how you use the picture. Remeber that there could be GPS location information is stored in the EXIF data. The data goes with your photos when they’re uploaded to photo-sharing sites. Don’t panic just yet. Photo navigation is still limited. The most important thing is to know exactly what is geotagged, although worrying about turning geotagging on and off is a little annoying. Check Javascript EXIF Reader example page to see this in use.

Typically you have needed special programs to read the EXIF data. Read EXIF data with Javascript article describes how to make small EXIF reader library capable of reading EXIF info from JPEG images. jQuery EXIF data plugin article describes a jQuery plugin that makes using EXIF data a matter of adding just a few lines of code.