What Is an ACB File?

Screenshot of several ACB files in Windows 10 that open with Photoshop

 Screenshot

A file with the ACB file extension is an Adobe Photoshop Color Book file. They're used to provide an easy way to comply with particular color standards, like for if you're printing an image versus using it for on-screen purposes.

AutoCAD Color Book files use the ACB extension too. Files of this type store collections of colors that the AutoCAD computer-aided design software can use to fill in surfaces and lines. They're useful for creating a template of colors that a company can use across all of their designs.

ACB is also the extension used for an archive file format utilized by AOL for software installations. ACB, in this case, stands for AOL Cab Launcher.

How to Open an ACB File

Adobe Photoshop Color Book ACB files are used with Adobe Photoshop, as well as Adobe's InDesign and Illustrator software programs. Photoshop stores several ACB files in its default installation directory under ...\Presets\Color Books\.

Some of the color catalogs included with Photoshop are FOCOLTONE, HKS, TRUMATCH, TOYO, and PANTONE. To use one of these ACB files, or any other in the aforementioned folder, open Photoshop's Color Picker tool. Choose the button called Color Libraries and then select the ACB file from the Book: drop-down menu.

You can also open Color Picker from either the foreground or the background color swatch on the Tools panel... it's the tool with the two overlapping colors.

Autodesk AutoCAD opens the AutoCAD Color Book ACB files used by that program. You can create your own ACB file for AutoCAD using the AutoCAD Color Book Editor. Just place the ACB files in the ...\Support\Color\ folder of AutoCAD's installation directory.

AutoCAD Color Book files are stored in the XML format, which means you can use any text editor to see the RGB values for each color.

As for AOL Cab Launcher files, it's likely that it's just an archive format, like ZIP or RAR, that AOL software utilizes during a program's installation phase. If you think your ACB file is used for this purpose, you can try to open it with a file extraction utility like 7-Zip.

Considering that there are several relatively common formats that use the ACB extension, you may find that the program that Windows is configured to open when you double-click or double-tap on these types of files isn't the one you'd like. If this is the case, it is possible to change the file associations in Windows to change it to the program you want.

How to Convert an ACB File

The free command-line tool ACB2XML for Windows can generate an XML file from an Adobe Photoshop Color Book file so that you can see each color book's lightness and chrominance values.

To do this, once you've downloaded and extracted ACB2XML to its own folder, execute this command in this manner from the same folder:

acb2xml.exe file.acb > file.xml

Be sure to swap out the file.acb file name with the right name for your ACB file. You can name the XML file whatever you like.