The file extension acb is used by the image editing software Adobe Photoshop for so-called Color Swatches files. In these color palettes are stored. These consist of a collection of color codes, names and color space specifications such as RGB, LAB or CMYK.
ACO Color palette files are used, for example, in image editing to save color palettes for reuse or to match a particular color standard. Depending on the intended use of the image (screen, print, etc.), certain color catalogs are better suited than others.
You can access the color palettes in Photoshop by clicking on the small arrow in the Swatches window. Photoshop already offers a number of different libraries included, including ANPA, FOCOLTONE, PANTONE and TRUMATCH.
With such ACO color files, colors of an image can also be saved as a color palette. In addition, there are thematically sorted ACO files on the Internet for download. To be able to use your own ACO file, you have to save it under 'Preferences / Swatches' in the Photoshop program folder.
Most often resolving problems with opening ACO files is very simple. Just install an appropriate program that supports such files. All of the listed programs support ACO files, but may vary in offered function and purpose. Some programs may be capable only of viewing contents of ACO files or offer file conversion options, but may not be capable of editing such files.
It is possible that although a compatible program has been installed on user’s system, it is not used by the system to open it. This may happen because no default application was associated with this type of files. To associate ACO files with given application, select "Open with" from drop-down menu (accessed by right-clicking on the file). Then select from the list the program or application you want to be used to open this type of file. If the Adobe Photoshop applications is not on the list, select "Browse" option in order to manually locate the directory where Adobe Photoshop has been installed.
Sometimes problems with opening ACO files may not lie with the application itself, but can arise due to other causes, such as: