.CTG File Extension

A CTG file is an index file created by Canon digital cameras. It contains information used to organize images stored on a camera's memory card. For example, CTG files record the number of images stored in a memory card folder and the dates on which those images were taken.

You're most likely to encounter CTG files when you've connected your Canon digital camera to a computer using a USB cable. They are stored in the following directory on your camera's memory card:

CANONSMC

CTG files are not image files; they contain no image data. Instead, they contain metadata your camera uses to organize and show photos on your camera and computer. Each CTG file corresponds to a specific image directory within your memory card. For example, the file 382.CTG contains information related to the images in the 382CANON directory.

You should not open, edit, or manually delete CTG files. Canon digital cameras automatically delete CTG files after the corresponding images are removed from a memory card.