The Unofficial Photoshop Color Book File Format Specification
Adobe Photoshop’s Color Picker has a Custom Colors dialog that offers a wide variety of colors from several industry-standard color catalogs such as ANPA, DIC, Focoltone and Pantone.
Adobe Photoshop’s Custom Colors Dialog
The color catalog data comes from Adobe Photoshop Color Book files. These file have the .ACB file extension on Windows and reside inside the “…/Presets/Color Book” folder in a typical installation.
Partly out of curiosity and partly because I needed the color data for a job, I went through reverse-engineering the file format since an official file format specification wasn’t readily available. I have put together what I’ve come up with into an unofficial file format specification. The plain text version can be downloaded from the link below:
Also see:
January 18th, 2007 at 2:14 pm
Hi! Thanks for this doc. Any idea what the ’spflspot’ stands for at the end of the acb files?
January 20th, 2007 at 11:46 am
Olivier: None of the acb files that I’ve check on my PC had “spflspot” at the end. Could it be just a color name in one your color books? Are you using a PC or a Mac? I have no evidence that the Mac format is exactly the same as the PC format (can someone please confirm if this is the case). Maybe there’s something specific to Macs…
January 28th, 2007 at 11:26 am
I was actually diving into the CS2 and CS3 color books because Photoshop CS3 is the only software I know has the latest Pantone pastel colours. These files end with spflspot for spot colors and spflproc for process colors. I’m now wondering what the spfl means…
January 28th, 2007 at 4:46 pm
I’ve checked a couple of ACB files from CS2 and, you’re right, they’re either trailed by a “spflspot” or a “spflproc”. It seems like Adobe has simply appended those to the ACB files based on whether they are spot or processes color books. A binary comparison between files from 7.0 and CS2 shows that the rest of the ACB file structure seems to be exactly the same. Thanks for pointing this out.
July 15th, 2007 at 7:56 pm
Thank you for your work. I really appreciate your determination in reverse engineering. Could you write an ACB compiler in your free time? That would be a great utility. Greetings from Poland!
July 16th, 2007 at 10:24 am
Marek: I do actually have an ACB generator that I wrote in C++, but it’s far from being a complete product. I also had started working on a PHP version but couldn’t get around to finish the UI code yet. Thanks a lot for your positive feedback!
Update: Check out the AdobeColorBook Java class by Mehmet D. Akin. It can be used for generating color books.
October 18th, 2007 at 9:03 am
Thanks. This is a big help for me. This adds my knowhow in Photoshop operation.
Kris