acb

Adobe Photoshop Color Book (ACB) encoder and decoder.

What

Adobe Photoshop's color picker allows you to pick colors from standard color libraries. These libraries reside as .acb files inside Photoshop's installation directory (e.g. /Applications/Adobe Photoshop/Presets/Color Books on macOS). This library allows you to decode and encode .acb files. You can extract color data from Photoshop's color books, as well as creating your own custom color books you can use them yourself or distribute them.

Install

npm install @atesgoral/acb
# Or:
yarn add @atesgoral/acb

Book structure

The output from the decoder and the expected input into the decoder looks something like this:

const book = {
  id: 42,
  title: 'Primary colors',
  description: 'Primary light colors, as perceived by humans.',
  colorNamePrefix: '',
  colorNamePostfix: '',
  pageSize: 3,
  pageKey: 1,
  colorModel: 'RGB',
  colors: [
    {name: 'Red', code: 'RED   ', components: [255, 0, 0]},
    {name: 'Green', code: 'GREEN ', components: [0, 255, 0]},
    {name: 'Blue', code: 'BLUE  ', components: [0, 0, 255]},
  ],
};

If you're using TypeScript, there is a ColorBook interface that is exported by the library:

import type {ColorBook} from '@atesgoral/acb';

const book: ColorBook = {
  // ...
};

All properties are mandatory:

field	description
id	The unique color book identifier. You must ensure that
	this does not conflict with an existing color book that
	exists in Photoshop's color book folder. Stock Photoshop
	color books seem to start at id 3000.
title	The color book title. Photoshop seems to show the
	filename instead of this.
description	The color book description. Photoshop doesn't show this
	anywhere. Use '^R' for the registered trademark symbol
	(®) and '^C' for the copyright symbol (©).
colorNamePrefix	The prefix to prepend to every color name.
colorNamePostfix	The suffix to append to every color name.
pageSize	The number of colors to show on every color page in the
	library color picker. The maximum that Photoshop allows
	is 9.
pageKey	Which color (by index) on a page to use as the color page
	key. For example, with 9 colors per page, 5 would be the
	middle of the page color.
colorModel	The color model of the color book. Valid values are:
	* 'RGB'
	* 'CMYK'
	* 'Lab'
	(import type {ColorModel} from '@atesgoral/acb';)
colors	And array of color records.

Each color record (import type {Color} from '@atesgoral/acb';) consists of the following mandatory properties:

field	description
name	The color name.
code	A 6-character unique code for the color.
components	An array of component values. For RGB, it's 3 values 0..255.
	For CMYK it's 4 values 0..100. For Lab the L component is
	0..100 while a and b are -128..127. (All ranges are inclusive.)

Decoding examples

Decoding from the standard input stream

import {AcbStreamDecoder} from '@atesgoral/acb';

const decoder = new AcbStreamDecoder();

decoder.on('book', (book) => {
  console.log(JSON.stringify(book, null, 2));
});

decoder.on('error', (error) => console.error(error));

process.stdin.pipe(decoder).pipe(process.stdout);

Decoding from a buffer

import {Readable} from 'stream';

import {AcbStreamDecoder} from '@atesgoral/acb';

const decoder = new AcbStreamDecoder();

decoder.on('book', (book) => {
  console.log(JSON.stringify(book, null, 2));
});

decoder.on('error', (error) => console.error(error));

const buffer = fs.readFileSync('./book.acb');

Readable.from(buffer).pipe(decoder).pipe(process.stdout);

Encoding examples

encodeAcb is a generator that yields Buffer chunks.

Encoding to the standard output stream

import {Readable} from 'stream';

import {encodeAcb} from '@atesgoral/acb';

const book = {
  // ...
};

const readable = Readable.from(encodeAcb(book));
readable.pipe(process.stdout);

Encoding into a single Buffer

import {encodeAcb} from '@atesgoral/acb';

const book = {
  // ...
};

const buffer = Buffer.concat([...encodeAcb(book)]);

Background

I reverse-engineered the ACB format back in 2003 before Adobe had it published publicly. I've been creating custom color books on the side for artists, printers and ink manifacturers. I've finally gotten around to publicly publishing a library that everyone can use.