How do I Open a CTG File online in Windows and MAC with a free .ctg opener

  • File type: Canon Catalog Index
  • MIME: application/binary


What is a CTG File extension

The CTG file extension is in the area of digital photography and video recording.

This particular format is part of the Canon brand of digital cameras and recorders. There it serves as the representation for catalog index files created in the canon digital cameras memory card of the device. And it normally resides within the folder CANONMSC.


Folder CanonMSC

The device in the memory card automatically creates this folder. It usually corresponds to other folders stored in the memory card used by the Canon devices. As a catalog, the CTG format file normally contains data on the number of images stored (or used to be stored) within the different folders created in the memory card.

The images commonly have a limit of 99 images associated with a catalog file. And anything that exceeds this number would prompt the creation of a new CTG format file.

One cannot open or edit this file manually. And it will be automatically deleted or erased by the camera device once the associated files are no longer present in the unit.

How to open CTG Files on Windows and MAC


  1. Search for the .ctg in your device.
  2. Double click on it
  3. Select open with option
  4. From the drop down list of apps and software select the viewer, app or program zoombrowser. If there is not any viewer installed you will have to download one of the programs we mentioned in the previous section.
  5. You can also try an hexadecimal editor like Ultraedit, HXD or Winhex



  1. Launch and Open one of the viewers installed: zoombrowser from cannon
  2. From the application go to the menu of files to open the .ctg file from your device.
  3. Now you can view the format in the app.

The image Size

Compared with JPG image file formats, the CTG extension is smaller in size but does not contain any image data which means that it cannot be transformed into any other image format.
Although closely identified with the Canon PowerShot digital camera series, this file format can also be utilized by other Canon photograph equipment. The bulk of the data contained in the catalog file primarily reference internal information associated with pictures taken with the camera and stored in its expanded memory.
This proprietary format of the Canon application is also for an archive collaboration between the index files and the component data. Data streams are normally differentiated based on the recording timestamps attached to the image files logged into the catalog file.
When formatting the memory card directly from the camera device, the CTG format file will install in the storage device by the camera.
This is not the case when the user initiates the format operation using a Personal Computer machine.
Usually the creation of the catalog files is in a series of increments. These are based on the last data stored by the camera unit in its storage card.
Other canon file formats are CIFF, CRW and CR2.


How do I convert CTG file to JPEG

The conversion is not possible. The CTG don’t have any image data inside.

Can I delete a CTG?

You can, but anytime you do it your canon camera will create it again.