.CTG

Open CTG File

Canon Catalog / ChessBase Opening Book

Quick Facts

Full NameCatalog / Chess Opening Tree

CategorySystem / Game Data

DeveloperCanon / ChessBase

MIME Typeapplication/octet-stream

⚠️ Important: This type Has Multiple Uses

The this format extension is used by two completely different applications. Identify your file type below to find the right solution.

What is a CTG File?

A CTG file can be one of two different file types:

📷 Canon Digital Camera Catalog

Created automatically by Canon digital cameras to index photos on memory cards. Stored in the CANONMSC folder.

Contains folder/image count information
Not meant to be opened by users
Automatically managed by camera
Do NOT delete manually

♟️ ChessBase Opening Book

Chess opening theory database used by ChessBase, Fritz, and other chess engines. Contains millions of positions and moves.

Stores opening moves and statistics
Requires CTB, CTO, INI companion files
Used by chess software for analysis
Can be opened with chess GUIs

Canon CTG Files: What You Need to Know

If you found CTG files on your Canon camera's memory card, here's what you should know:

📁 Location

Canon CTG files are stored in:

[Memory Card]/CANONMSC/M0100the file
[Memory Card]/CANONMSC/M0200.CTG

Each CTG file corresponds to a folder in the DCIM directory (100CANON, 200CANON, etc.).

🚫 Do NOT Open or Delete

Canon CTG files are internal catalog files that:

Index how many images are in each folder
Help the camera navigate your photos
Are automatically created when you take photos
Are automatically deleted when you erase photos

⚠️ Warning: Manually deleting CTG files can cause indexing problems on your camera. Let the camera manage these files automatically.

✅ Your Photos Are Safe

CTG files do not contain your actual photos. Your images are stored as JPG, CR2, or CR3 files in the DCIM folders. If you're looking for your photos, check the DCIM/100CANON/ folder on your memory card.

ChessBase CTG Opening Books: How to Open

If you have a chess opening book in CTG format, here's how to use it:

📦 Required Files

A complete ChessBase opening book consists of 4 files:

File	Purpose	Required
bookthese files	Main opening data (positions, moves, stats)	✅ Yes
book.ctb	Bitmap index for free pages	✅ Yes
book.cto	Lookup table for fast access	✅ Yes
book.ini	Auxiliary configuration	✅ Yes

All four files must be in the same folder for the opening book to work.

Programs That Open CTG Chess Files

Program	Platform	Best For	Price
ChessBase 17	Windows	Professional analysis	€199+
Fritz 19	Windows	Playing & training	€79
HIARCS Chess Explorer	Windows, Mac	Cross-platform use	€49
Shredder Chess	Windows, Mac	Engine play	€49
Arena Chess GUI	Windows	Free alternative	Free

Free The format Opening Books

You can download free This file opening books from:

HIARCS: Free opening book downloads
The Week in Chess: Weekly updated CTG databases

Converting CTG to Other Formats

The CTG format is proprietary, but you can convert to Polyglot (.bin) format using:

the fileexporter - Open source CTG to Polyglot converter (GitHub)
ChessBase - Export to PGN (partial data only)

How to Identify Your This format File Type

If you found it...	It's probably...	What to do
On a Canon memory card in CANONMSC folder	Canon Camera Catalog	Leave it alone
With .ctb, .cto, .ini files	ChessBase Opening Book	Open with chess software
Downloaded from chess website	ChessBase Opening Book	Open with chess software
File size ~6KB	Canon Camera Catalog	Leave it alone
File size 10MB+	ChessBase Opening Book	Open with chess software

Frequently Asked Questions About Opening CTG Files

What is a These files file? +

A CTG file has two common uses: Canon Digital Camera Catalog files that index photos on memory cards, and ChessBase Opening Book files containing chess opening theory and statistics.

Can I open Canon CTG files? +

Canon CTG files are not meant to be opened manually. They are internal catalog files used by Canon cameras to index photos. Do not delete them as they are needed for the camera to function properly.

How do I open ChessBase The file files? +

ChessBase CTG opening books can be opened with ChessBase, Fritz, Shredder, HIARCS Chess Explorer, or any chess GUI that supports the This type format. The CTG file must be accompanied by CTB, CTO, and INI files.

Can I delete CTG files from my camera's memory card? +

No, do not manually delete Canon CTG files. They are automatically created and deleted by the camera when you take or remove photos. Deleting them may cause issues with your camera's indexing system.

Where are CTG files located on Canon cameras? +

Canon CTG files are stored in the CANONMSC folder on the camera's memory card. Each CTG file corresponds to a DCIM subfolder containing images.

Can I convert CTG chess opening books to other formats? +

Yes, you can convert CTG opening books to Polyglot (.bin) format using tools like ctgexporter. However, the CTG format is proprietary and conversion may result in some data loss.

Why does my These files file say "cannot open"? +

If it's a Canon CTG file, it's not designed to be opened. If it's a ChessBase This format file, make sure you have the companion .ctb, .cto, and .ini files in the same folder, and that you're using compatible chess software.

Are there free programs to open CTG chess files? +

Yes, Arena Chess GUI is a free Windows program that can read CTG opening books. For other platforms, you may need commercial software like ChessBase or HIARCS Chess Explorer.

Related File Types

Quick Summary: How to Open CTG File

To open CTG file: First identify the type. Canon camera CTG files should NOT be opened - they're internal catalog files. ChessBase CTG files (chess opening books) can be opened with ChessBase, Fritz, HIARCS, or Arena Chess GUI. Make sure you have all companion files (.ctb, .cto, .ini) in the same folder.