Color Conversion - Electron

Convert colors between sRGB, CMYK, and spot color spaces programmatically in CE.SDK.

Color Conversion example showing color blocks with different color spaces

10 mins

estimated time

CE.SDK supports three color spaces: sRGB, CMYK, and SpotColor. When building color interfaces or preparing designs for export, you may need to convert colors between these spaces. The engine handles the mathematical conversion automatically through the convertColorToColorSpace() API.

import type { EditorPlugin, EditorPluginContext } from '@cesdk/cesdk-js';
import packageJson from './package.json';

// Type guard helpers for identifying color types
function isRGBAColor(
  color: any
): color is { r: number; g: number; b: number; a: number } {
  return 'r' in color && 'g' in color && 'b' in color && 'a' in color;
}

function isCMYKColor(
  color: any
): color is { c: number; m: number; y: number; k: number; tint: number } {
  return 'c' in color && 'm' in color && 'y' in color && 'k' in color;
}

function isSpotColor(
  color: any
): color is { name: string; tint: number; externalReference: string } {
  return 'name' in color && 'tint' in color && 'externalReference' in color;
}

class Example implements EditorPlugin {
  name = packageJson.name;
  version = packageJson.version;

  async initialize({ cesdk }: EditorPluginContext): Promise<void> {
    if (!cesdk) {
      throw new Error('CE.SDK instance is required for this plugin');
    }

    // Enable spot color feature for the UI
    cesdk.feature.enable('ly.img.spotColor');

    await cesdk.addDefaultAssetSources();
    await cesdk.addDemoAssetSources({
      sceneMode: 'Design',
      withUploadAssetSources: true
    });
    await cesdk.createDesignScene();

    const engine = cesdk.engine;
    const page = engine.block.findByType('page')[0];

    // Set page dimensions
    engine.block.setWidth(page, 800);
    engine.block.setHeight(page, 600);

    const pageWidth = engine.block.getWidth(page);
    const pageHeight = engine.block.getHeight(page);

    // Calculate block sizes for three columns
    const margin = 40;
    const spacing = 30;
    const availableWidth = pageWidth - 2 * margin - 2 * spacing;
    const blockWidth = availableWidth / 3;
    const blockHeight = pageHeight - 2 * margin - 80; // Leave space for labels

    // Define a spot color with RGB approximation for screen preview
    engine.editor.setSpotColorRGB('Brand Red', 0.95, 0.25, 0.21);

    // Create three blocks with different color spaces

    // Block 1: sRGB color (for screen display)
    const srgbBlock = engine.block.create('//ly.img.ubq/graphic');
    engine.block.setShape(
      srgbBlock,
      engine.block.createShape('//ly.img.ubq/shape/rect')
    );
    const srgbFill = engine.block.createFill('//ly.img.ubq/fill/color');
    engine.block.setColor(srgbFill, 'fill/color/value', {
      r: 0.2,
      g: 0.4,
      b: 0.9,
      a: 1.0
    });
    engine.block.setFill(srgbBlock, srgbFill);
    engine.block.setWidth(srgbBlock, blockWidth);
    engine.block.setHeight(srgbBlock, blockHeight);
    engine.block.appendChild(page, srgbBlock);

    // Block 2: CMYK color (for print workflows)
    const cmykBlock = engine.block.create('//ly.img.ubq/graphic');
    engine.block.setShape(
      cmykBlock,
      engine.block.createShape('//ly.img.ubq/shape/rect')
    );
    const cmykFill = engine.block.createFill('//ly.img.ubq/fill/color');
    engine.block.setColor(cmykFill, 'fill/color/value', {
      c: 0.0,
      m: 0.8,
      y: 0.95,
      k: 0.0,
      tint: 1.0
    });
    engine.block.setFill(cmykBlock, cmykFill);
    engine.block.setWidth(cmykBlock, blockWidth);
    engine.block.setHeight(cmykBlock, blockHeight);
    engine.block.appendChild(page, cmykBlock);

    // Block 3: Spot color (for specialized printing)
    const spotBlock = engine.block.create('//ly.img.ubq/graphic');
    engine.block.setShape(
      spotBlock,
      engine.block.createShape('//ly.img.ubq/shape/rect')
    );
    const spotFill = engine.block.createFill('//ly.img.ubq/fill/color');
    engine.block.setColor(spotFill, 'fill/color/value', {
      name: 'Brand Red',
      tint: 1.0,
      externalReference: ''
    });
    engine.block.setFill(spotBlock, spotFill);
    engine.block.setWidth(spotBlock, blockWidth);
    engine.block.setHeight(spotBlock, blockHeight);
    engine.block.appendChild(page, spotBlock);

    // Position all color blocks
    engine.block.setPositionX(srgbBlock, margin);
    engine.block.setPositionY(srgbBlock, margin);

    engine.block.setPositionX(cmykBlock, margin + blockWidth + spacing);
    engine.block.setPositionY(cmykBlock, margin);

    engine.block.setPositionX(spotBlock, margin + 2 * (blockWidth + spacing));
    engine.block.setPositionY(spotBlock, margin);

    // Create labels for each color space
    const labelY = margin + blockHeight + 20;
    const fontSize = 24;

    const labels = [
      { text: 'sRGB', x: margin + blockWidth / 2 },
      { text: 'CMYK', x: margin + blockWidth + spacing + blockWidth / 2 },
      {
        text: 'Spot Color',
        x: margin + 2 * (blockWidth + spacing) + blockWidth / 2
      }
    ];

    for (const label of labels) {
      const textBlock = engine.block.create('//ly.img.ubq/text');
      engine.block.replaceText(textBlock, label.text);
      engine.block.setTextFontSize(textBlock, fontSize);
      engine.block.setWidthMode(textBlock, 'Auto');
      engine.block.setHeightMode(textBlock, 'Auto');
      engine.block.appendChild(page, textBlock);

      // Center the label below each block
      const textWidth = engine.block.getWidth(textBlock);
      engine.block.setPositionX(textBlock, label.x - textWidth / 2);
      engine.block.setPositionY(textBlock, labelY);
    }

    // Convert colors to sRGB for screen display
    const srgbColor = engine.block.getColor(srgbFill, 'fill/color/value');
    const cmykColor = engine.block.getColor(cmykFill, 'fill/color/value');
    const spotColor = engine.block.getColor(spotFill, 'fill/color/value');

    // Convert CMYK to sRGB
    const cmykToRgba = engine.editor.convertColorToColorSpace(
      cmykColor,
      'sRGB'
    );
    console.log('CMYK converted to sRGB:', cmykToRgba);

    // Convert Spot color to sRGB (uses defined RGB approximation)
    const spotToRgba = engine.editor.convertColorToColorSpace(
      spotColor,
      'sRGB'
    );
    console.log('Spot color converted to sRGB:', spotToRgba);

    // Convert colors to CMYK for print workflows
    const srgbToCmyk = engine.editor.convertColorToColorSpace(
      srgbColor,
      'CMYK'
    );
    console.log('sRGB converted to CMYK:', srgbToCmyk);

    // Convert Spot color to CMYK for print output
    // First define CMYK approximation for the spot color
    engine.editor.setSpotColorCMYK('Brand Red', 0.0, 0.85, 0.9, 0.05);
    const spotToCmyk = engine.editor.convertColorToColorSpace(
      spotColor,
      'CMYK'
    );
    console.log('Spot color converted to CMYK:', spotToCmyk);

    // Use type guards to identify color space before conversion
    if (isRGBAColor(srgbColor)) {
      console.log(
        'sRGB color components:',
        `R: ${srgbColor.r}, G: ${srgbColor.g}, B: ${srgbColor.b}, A: ${srgbColor.a}`
      );
    }

    if (isCMYKColor(cmykColor)) {
      console.log(
        'CMYK color components:',
        `C: ${cmykColor.c}, M: ${cmykColor.m}, Y: ${cmykColor.y}, K: ${cmykColor.k}, Tint: ${cmykColor.tint}`
      );
    }

    if (isSpotColor(spotColor)) {
      console.log('Spot color name:', spotColor.name, 'Tint:', spotColor.tint);
    }

    console.log('Color Conversion example loaded successfully');
  }
}

export default Example;

This guide covers how to convert colors between sRGB and CMYK, handle spot color conversions, identify color types with type guards, and understand how tint and alpha values are preserved during conversion.

Supported Color Spaces#

CE.SDK supports conversion between three color spaces:

Color Space	Format	Use Case
sRGB	`RGBAColor` with `r`, `g`, `b`, `a` (0.0-1.0)	Screen display, web output
CMYK	`CMYKColor` with `c`, `m`, `y`, `k`, `tint` (0.0-1.0)	Print workflows
SpotColor	`SpotColor` with `name`, `tint`, `externalReference`	Specialized printing

Setting Up Colors#

Before converting colors, you need colors in different spaces. This example creates blocks with sRGB, CMYK, and spot colors.

First, define a spot color with its RGB approximation for screen preview:

// Define a spot color with RGB approximation for screen preview
engine.editor.setSpotColorRGB('Brand Red', 0.95, 0.25, 0.21);

Create an sRGB color block for screen display:

// Block 1: sRGB color (for screen display)
const srgbBlock = engine.block.create('//ly.img.ubq/graphic');
engine.block.setShape(
  srgbBlock,
  engine.block.createShape('//ly.img.ubq/shape/rect')
);
const srgbFill = engine.block.createFill('//ly.img.ubq/fill/color');
engine.block.setColor(srgbFill, 'fill/color/value', {
  r: 0.2,
  g: 0.4,
  b: 0.9,
  a: 1.0
});
engine.block.setFill(srgbBlock, srgbFill);
engine.block.setWidth(srgbBlock, blockWidth);
engine.block.setHeight(srgbBlock, blockHeight);
engine.block.appendChild(page, srgbBlock);

Create a CMYK color block for print workflows:

// Block 2: CMYK color (for print workflows)
const cmykBlock = engine.block.create('//ly.img.ubq/graphic');
engine.block.setShape(
  cmykBlock,
  engine.block.createShape('//ly.img.ubq/shape/rect')
);
const cmykFill = engine.block.createFill('//ly.img.ubq/fill/color');
engine.block.setColor(cmykFill, 'fill/color/value', {
  c: 0.0,
  m: 0.8,
  y: 0.95,
  k: 0.0,
  tint: 1.0
});
engine.block.setFill(cmykBlock, cmykFill);
engine.block.setWidth(cmykBlock, blockWidth);
engine.block.setHeight(cmykBlock, blockHeight);
engine.block.appendChild(page, cmykBlock);

Create a spot color block for specialized printing:

// Block 3: Spot color (for specialized printing)
const spotBlock = engine.block.create('//ly.img.ubq/graphic');
engine.block.setShape(
  spotBlock,
  engine.block.createShape('//ly.img.ubq/shape/rect')
);
const spotFill = engine.block.createFill('//ly.img.ubq/fill/color');
engine.block.setColor(spotFill, 'fill/color/value', {
  name: 'Brand Red',
  tint: 1.0,
  externalReference: ''
});
engine.block.setFill(spotBlock, spotFill);
engine.block.setWidth(spotBlock, blockWidth);
engine.block.setHeight(spotBlock, blockHeight);
engine.block.appendChild(page, spotBlock);

Converting to sRGB#

Use engine.editor.convertColorToColorSpace(color, 'sRGB') to convert any color to sRGB format. This is useful for displaying color values on screen or when you need RGB components for CSS or other web-based color operations.

// Convert colors to sRGB for screen display
const srgbColor = engine.block.getColor(srgbFill, 'fill/color/value');
const cmykColor = engine.block.getColor(cmykFill, 'fill/color/value');
const spotColor = engine.block.getColor(spotFill, 'fill/color/value');

// Convert CMYK to sRGB
const cmykToRgba = engine.editor.convertColorToColorSpace(
  cmykColor,
  'sRGB'
);
console.log('CMYK converted to sRGB:', cmykToRgba);

// Convert Spot color to sRGB (uses defined RGB approximation)
const spotToRgba = engine.editor.convertColorToColorSpace(
  spotColor,
  'sRGB'
);
console.log('Spot color converted to sRGB:', spotToRgba);

When converting CMYK or spot colors to sRGB, the engine returns an RGBAColor object with r, g, b, a properties. The tint value from CMYK or spot colors becomes the alpha value in the returned sRGB color.

Converting to CMYK#

Use engine.editor.convertColorToColorSpace(color, 'CMYK') to convert any color to CMYK format. This is essential for print workflows where you need to ensure colors are in the correct space before export.

// Convert colors to CMYK for print workflows
const srgbToCmyk = engine.editor.convertColorToColorSpace(
  srgbColor,
  'CMYK'
);
console.log('sRGB converted to CMYK:', srgbToCmyk);

// Convert Spot color to CMYK for print output
// First define CMYK approximation for the spot color
engine.editor.setSpotColorCMYK('Brand Red', 0.0, 0.85, 0.9, 0.05);
const spotToCmyk = engine.editor.convertColorToColorSpace(
  spotColor,
  'CMYK'
);
console.log('Spot color converted to CMYK:', spotToCmyk);

When converting sRGB colors to CMYK, the alpha value becomes the tint value in the returned CMYK color. For spot colors, define a CMYK approximation with setSpotColorCMYK() before converting.

Identifying Color Types#

Before converting a color, you may need to identify its current color space. CE.SDK provides type guard functions to check the color type.

// Use type guards to identify color space before conversion
if (isRGBAColor(srgbColor)) {
  console.log(
    'sRGB color components:',
    `R: ${srgbColor.r}, G: ${srgbColor.g}, B: ${srgbColor.b}, A: ${srgbColor.a}`
  );
}

if (isCMYKColor(cmykColor)) {
  console.log(
    'CMYK color components:',
    `C: ${cmykColor.c}, M: ${cmykColor.m}, Y: ${cmykColor.y}, K: ${cmykColor.k}, Tint: ${cmykColor.tint}`
  );
}

if (isSpotColor(spotColor)) {
  console.log('Spot color name:', spotColor.name, 'Tint:', spotColor.tint);
}

Import the type guards from @cesdk/cesdk-js:

isRGBAColor() - Returns true if the color is an sRGB color
isCMYKColor() - Returns true if the color is a CMYK color
isSpotColor() - Returns true if the color is a spot color

Handling Tint and Alpha#

The tint and alpha values represent transparency in different color spaces:

Source	Target	Transformation
sRGB (alpha)	CMYK	Alpha becomes tint
CMYK (tint)	sRGB	Tint becomes alpha
SpotColor (tint)	sRGB	Tint becomes alpha
SpotColor (tint)	CMYK	Tint is preserved

Practical Use Cases#

Building a Color Picker#

When displaying a color value from a block in a custom color picker, convert to sRGB to show RGB values:

const fillColor = engine.block.getColor(fillId, 'fill/color/value');
const rgbaColor = engine.editor.convertColorToColorSpace(fillColor, 'sRGB');
// Display: R: ${rgbaColor.r * 255}, G: ${rgbaColor.g * 255}, B: ${rgbaColor.b * 255}

Export Preparation#

Before PDF export for print, verify colors are in CMYK format:

const color = engine.block.getColor(blockId, 'fill/color/value');
if (!isCMYKColor(color)) {
  const cmykColor = engine.editor.convertColorToColorSpace(color, 'CMYK');
  // Log or display the CMYK values
  console.log(`C: ${cmykColor.c}, M: ${cmykColor.m}, Y: ${cmykColor.y}, K: ${cmykColor.k}`);
}

Troubleshooting#

Issue	Cause	Solution
Spot color converts to unexpected values	Spot color not defined	Call `setSpotColorRGB()` or `setSpotColorCMYK()` before conversion
Colors look different after conversion	Color gamut differences	Some sRGB colors cannot be exactly represented in CMYK
Type errors with converted colors	Wrong type assumption	Use type guards (`isRGBAColor`, `isCMYKColor`, `isSpotColor`) before accessing properties

API Reference#

Method	Description
`engine.editor.convertColorToColorSpace(color, colorSpace)`	Convert a color to the target color space. Returns an `RGBAColor` for ‘sRGB’ or `CMYKColor` for ‘CMYK’.
`engine.editor.setSpotColorRGB(name, r, g, b)`	Define a spot color with an RGB approximation. Components range from 0.0 to 1.0.
`engine.editor.setSpotColorCMYK(name, c, m, y, k)`	Define a spot color with a CMYK approximation. Components range from 0.0 to 1.0.

Type Guard	Description
`isRGBAColor(color)`	Returns true if the color is an `RGBAColor` object
`isCMYKColor(color)`	Returns true if the color is a `CMYKColor` object
`isSpotColor(color)`	Returns true if the color is a `SpotColor` object