Adobe Photoshop Application File Extensions

Multiple Adobe Photoshop advanced features allow saving their setup and data in a feature specific data files. Special file extensions are used by each feature. They include:

ATN file extension. Actions from actions palette. Photoshop actions are series of steps recorded by designer or developer to create a certain effect.
AMP file extension. Arbitrary map effect file which adjusts brightness of an image layer according to the data stored in the file.
API file extension. CMYK color settings file.
ACB file extension. Photoshop color books. Used to load custom color books into Adobe Photoshop. These includes tables provided by known color swatches vendors including Pantone, Focoltone, Trumatch, Toyo, or HKS. Custom color books could be created by users.
ACT file extension. Photoshop color tables. Contains color table of 256 RGB colors. Color table file is 768- or 772-bytes longs. First color is indexed as zero.
ACO file extension. Photoshop color swatches palette. Similar to color books contains collection of colors from Pantone, Focoltone, Trumatch, Toyo, HKS, or custom color collection created by users.
SHC file extension. Contour settings files.
CRV file extension. Curves are used in multiple Adobe Photoshop dialog including Curves dialog, Duotone Curve dialog, and Print Transfer dialog. Curves are stored in 0 to 255 coordinates range.
ACF file extension. Photoshop Custom Filter dialog kernels.
ADO file extension. Duotone options file loaded and saved in the Duotone Options dialog.
AHS file extension. Halftone screen settings.
AHV file extension. Hue/saturations image settings. Stores master hue, saturation, lightness and colorization set in Photoshop Hue/Saturation dialog.
ALV file extension. Image levels settings.
AMS file extension. Monitor settings accessible from the Photoshop Color Settings dialog.
AXT file extension. Image replace color settings.
ASV file extension. Selective color settings.
AST file extension. Separation tables settings from the Separation Tables dialog.
ATF file extension. Photoshop transfer function settings.