What is the difference between ASE and ACO?
Both are Adobe palette formats. ACO is Photoshop’s own swatch file; ASE (Adobe Swatch Exchange) is the one Adobe made for sharing swatches between Photoshop, Illustrator and InDesign. Other apps support one, the other or both, which is why converting between them comes up.
| .aco (Photoshop Color Swatches) | .ase (Adobe Swatch Exchange) | |
|---|---|---|
| Made by | Photoshop | Photoshop, Illustrator, InDesign |
| Color values | 16-bit whole numbers per channel | 32-bit decimals per channel |
| Color models | RGB, HSB, CMYK, Lab, grayscale, plus color book references | RGB, CMYK, Lab, grayscale |
| Color names | Only in the version 2 section | Yes |
| Groups | No | Yes |
| Read by | Photoshop, Clip Studio Paint, Krita, GIMP, Procreate | Photoshop, Illustrator, InDesign, Affinity, Krita, GIMP, Procreate |
The .aco layout is from Adobe’s Photoshop File Formats Specification, section “Color Swatches”. The .ase layout is documented at selapa.net. The app list comes from each app’s manual: Clip Studio Paint imports .aco but not .ase, Krita and GIMP import both, Procreate imports both with New from File, and Affinity imports .ase.
Which formats does it read and write?
| Format | Reads | Writes | Color names |
|---|---|---|---|
Adobe Swatch Exchange .ase |
RGB, CMYK, Lab, grayscale; all groups | RGB, one group | Kept |
Photoshop swatches .aco |
Versions 1 and 2; RGB, HSB, CMYK, Lab, grayscale | Versions 1 and 2, RGB | Kept |
GIMP palette .gpl |
Yes, including Aseprite’s RGBA variant | Yes | Kept |
Krita palette .kpl |
sRGB, RGB, CMYK, Lab, grayscale; all groups | sRGB | Kept |
Procreate .swatches |
Yes | Up to 30 colors per file | Procreate has none |
Photoshop color table .act |
Yes | No | None in the format |
JASC / Paint Shop Pro .pal |
Yes | No | None in the format |
| Hex codes (text, CSS, pasted) | Yes | Hex list and CSS variables | CSS variable names kept |
.zip of any of these |
Yes | All formats as ZIP |
Colors without a name, such as those from a Procreate palette or a hex list, are named after their hex code in the files that store names.
Is it an Adobe .ase or an Aseprite .ase?
Aseprite, the pixel art editor, saves its sprites as .ase or .aseprite. The two kinds of file have nothing else in common, so Photoshop can’t open an Aseprite file and Aseprite can’t load an Adobe palette from it. The converter tells them apart by their first bytes: an Adobe palette starts with the letters ASEF, and an Aseprite sprite has the number A5E0 at byte 4. When you drop an Aseprite sprite, it reads the palette stored in the sprite’s first frame, says that it was a sprite, and lets you save those colors as a palette for any app.
What happens to CMYK and Lab colors?
They are converted to RGB, because every format this page writes stores RGB. CMYK uses the plain formula without an ink profile, and Lab is converted from the D50 white point Adobe files use to sRGB with the Bradford chromatic adaptation method. Photoshop converts CMYK through a color profile, so a CMYK swatch can look a little different here than in Photoshop. The palette card says how many colors were converted. Colors stored only as a reference to a color book, such as Pantone entries in an .aco file, carry no color values and are left out.
What it doesn’t do
- It doesn’t keep CMYK, Lab or spot colors as they are. Everything is saved as RGB. For print work with exact CMYK or spot swatches, keep the original file.
- It doesn’t keep groups. Groups in an .ase or .kpl file are merged into one palette in their original order.
- It doesn’t read other apps’ own formats such as Clip Studio Paint
.cls, macOS.clror Adobe color books.acb.
How this page was tested
On 15 October 2026 we dropped five files at once on this page in headless Chrome on a Linux desktop:
- An .ase file written by a separate script from the format description, with two groups and colors in RGB, CMYK, Lab and grayscale.
- An .aco file with version 1 and version 2 sections, three named colors, one of them stored as HSB.
- A 16-color GIMP palette shipped with Aseprite.
- An Aseprite sprite from Aseprite’s MIT-licensed test files, saved as
.ase. - A Procreate 5
.swatchesfile from the MIT-licensed procreate-swatches project.
All five opened, with the color names stored in the .ase, .aco and .gpl files. The CMYK cyan came out as #00FFFF, Lab white as #FFFFFF, 50% gray as #808080 and the HSB red as #FF0000, and the sprite was labeled as an Aseprite file. We downloaded .aco, .ase, .gpl, .kpl and .swatches files from them and read each back with separate readers written from the format descriptions: colors and names matched. A 64-color GIMP palette saved as .swatches became three files of 30, 30 and 4 colors, with all 64 in order. The converter’s automated tests also write every format and read it back, with each color within 1/255 of the original.
We have not yet tested .ase or .aco files saved by Photoshop or Illustrator themselves, and have not imported the downloads into Photoshop, Clip Studio Paint, Krita, GIMP, Affinity or Procreate.