EOS digital SLRs can record each image as either a RAW image, JPEG image, or both simultaneously.
Like a digital negative, RAW images contain all the unprocessed data from the camera’s sensor. Recorded at up to 14 bits per pixel on selected models, RAW images provide the maximum post processing flexibility. Picture Style information is stored in the image header, so parameters can be adjusted after the shoot without affecting the original image data. Picture Style settings will only be fixed in the image if it is converted to a JPEG. Digital Photo Professional software is provided for RAW image handling.
JPEG images have compression and Picture Style processing applied and are designed to be more usable straight out of the camera. Depending on the desired file size, different levels of compression can be applied.