COL File

What are COL files and how to open them

Are you having problems opening a COL file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your COL files.

What is a COL file?

COL files have multiple uses, and Buze Color Theme is one of them. Read more about the other uses further down the page.

Buze Color Theme

We have not yet analyzed in detail what these files contain and what they are used for. We're working on it.

How to open COL files

Important: Different programs may use files with the COL file extension for different purposes, so unless you are sure which format your COL file is, you may need to try a few different programs.

While we have not verified the apps ourselves yet, our users have suggested ten different COL openers which you will find listed below.

Last updated: September 2, 2026

All known file formats using extension .COL

While Buze Color Theme is a popular type of COL-file, we know of 9 different uses of the .COL file extension. Different software may use files with the same extension for different types of data.

Capture One Session File

Capture One Session Files with the .COL extension are legacy project-oriented files used by Capture One before newer formats. They accompany sessions as the "session database," storing information about how a project is organized - such as which albums or favorites exist, which images are selected, where session folders are located - and session-level metadata. These files do not contain the image adjustments or rendered previews themselves.

Capture One writes .COL (and variants like .COL50, .COL60) files when creating a Session in older versions. Adjustments, previews, thumbnails, masks and other developed data are saved separately in sidecar files in the CaptureOne/Settings and CaptureOne/Cache subfolders alongside the RAW or source images. Later versions of Capture One replaced .COL-based session files with .COSESSIONDB files, though older .COL sessions remain readable.

The .COL file is binary and proprietary. It does not itself include image-raw or preview data; it holds structural metadata only. The adjustment data resides in .cos files (and other sidecar files) located in CaptureOne/Settings* folders.

COL opener for Windows

We have identified one COL opener that is compatible with this specific type of COL file.

Dark Legions Color Palette

Dark Legions Color Palette files specify the palette used in the 1994 strategy/action game Dark Legions by Silicon Knights. They store 256 colours that the game uses when displaying graphics, so that sprites and terrain appear in the intended hues. Each file provides a full VGA-style palette with red, green and blue components.

These palette files are created by the game itself or by tools modifying its assets. Game graphics stored elsewhere (archives or bitmap data) use these palette files to map colour indices to actual RGB values when shown on screen. That means changing a palette file alters the appearance of many graphics without touching the graphics data itself.

Files always begin with a small header: first a 32-bit little-endian file length (always 776 bytes for official files), then a magic signature value of 0xB123. After that comes the palette data: 256 entries, each consisting of three bytes (one each for red, green and blue), where each component takes the full 0-255 range.

Grand Theft Auto 3 Collision Data

Files that contain the .col file extension are most commonly associated with the Grand Theft Auto video games. These files contain collision information for objects within the associated video game. The COL files used by these video game applications determine the location and the extent of the object damage during a gameplay collision.

HTML Help Collection

HTML Help Collection files store metadata that ties together multiple already-compiled HTML Help files (CHM files) into a single merged help set called a collection. These collections are used when programs combine several distinct CHM help sets - such as plug-ins or snap-ins - into one unified help system with a shared table of contents, index, and search features.

Microsoft Management Console (MMC) is the primary software that creates these collection files when it builds the help content for a console file including multiple snap-ins. Each collection file points to each contributing CHM file, arranges their hierarchy via folder titles and ordering, and assigns language identifiers. The collection file is interpreted at runtime by the HTML Help system so that help entries in different CHMs appear as if part of one resource.

These collection files are structured as XML. The root element is HTMLHelpCollection. It begins with metadata elements including masterchm (the base CHM file name), masterlangid (language ID), collectionnum, refcount, version, and samplelocation. Then a nested Folders element appears, containing Folder elements that specify the visible titles via TitleString attributes, their order via FolderOrder, possible subfolders, and individual CHM entries via terminal Folder elements that include LangId when relevant.

The file begins with an ASCII signature ("<XML>…<HTMLHelpCollection>") at offset zero. Among internal identifiers are tags and attributes named SAMPLELOCATION, COLLECTIONNUM, VERSION, FOLDERORDER, TITLESTRING, REFCOUNT, LANGID, FOLDERS, and FOLDER elements.

Jeskola Buzz Theme

We know that one COL format is Jeskola Buzz Theme. We have not yet analyzed in detail what these files contain and what they are used for. We're working on it.

Lotus Notes Colum Descriptor File

The Lotus Notes software application has also been known to use the .col file suffix. Lotus Notes is a collaboration software created by the Lotus Development Corp, which IBM later acquired. The COL files used by this program contain column description files referenced by the Lotus Notes software.

Makkoya Palette

We know that one COL format is Makkoya Palette. We have not yet analyzed in detail what these files contain and what they are used for. We're working on it.

PPrint Color Map File

We know that one COL format is PPrint Color Map File. We have not yet analyzed in detail what these files contain and what they are used for. We're working on it.

Various apps that use files with this extension

These apps are known to open certain types of COL files. Remember, different programs may use COL files for different purposes, so you may need to try out a few of them to be able to open your specific file.

Help us help others

File.org helps thousands of users every day, and we would love to hear from you if you have additional information about COL file formats, example files, or compatible programs. Please use the links below or email us at submit@file.org to discuss further.