.ACO File Extension

ACO files are useful for controlling colors for different publishing media, such as digital image files and paper prints. Several color swatch files are included with the Adobe Photoshop installation in the /​Presets/​Color Swatches/​ directory, which include colors for the ANPA, FOCOLTONE, HKS, PANTONE, TOYO, and TRUMATCH standards.

To open a .aco file, you need compatible software that supports this file format.