Extract Dominant Image Colors in JavaScript – major-color-picker

major-color-picker is a lightweight JavaScript utility that extracts the most dominant color from an image.

The library uses the HTML Canvas API to read pixel data from an image and calculates the average color. It then returns this color as a HEX string, which can be used to dynamically style your UI elements.

For instance, you could adjust a container’s background to match a user’s uploaded profile picture.

How to use it:

1. Install major-color-picker and import the getDominantColorFromImage function into your project.

# NPM
$ npm install major-color-picker

import { getDominantColorFromImage } from 'major-color-picker';

2. Connect it to a file input element:

<input type="file" id="image-picker" accept="image/*">
<div id="color-box" style="width: 100px; height: 100px; margin-top: 10px;"></div>
<p id="color-value"></p>

const imagePicker = document.getElementById('image-picker');
const colorBox = document.getElementById('color-box');
const colorValue = document.getElementById('color-value');
imagePicker.addEventListener('change', async (e) => {
  const file = e.target.files?.[0];
  if (file) {
    try {
      const color = await getDominantColorFromImage(file);
      colorBox.style.backgroundColor = color;
      colorValue.textContent = `Average color: ${color}`;
    } catch (error) {
      console.error('Error getting color:', error);
    }
  }
});

Best practices We Learned:

• Always handle errors: Large images or corrupted files can trigger rejections. Wrap calls in try/catch like the example.
• Throttle rapid inputs: If users spam-upload images, add a debounce (e.g., 300ms) to avoid canvas overload.
• Avoid processing huge images: This analyzes pixel data directly. For >2MB images, resize first using a library like browser-image-compression.
• Don’t use in loops: Processing multiple images sequentially? Add await between calls to prevent UI freezing.

FAQs

Q: Does it find the most frequent color or the average color?
A: The library calculates the average color of the sampled pixels, not the most frequent one (the statistical mode). This is faster but can sometimes result in a muddy brown or gray if the image has many contrasting colors that average each other out.

Q: Can I use this with an image URL?
A: The library is designed to accept a File object from a file input. To use a URL, you would need to first fetch the image, convert the response to a Blob, and then pass that blob to the function. Keep in mind cross-origin (CORS) policies can block you from analyzing images from other domains.

Q: Why is the extracted color sometimes a dull brown?
A: This is a common outcome of color averaging. If you have an image that is half bright blue and half bright yellow, the average color will be a dull, grayish-green. The library isn’t looking for the most vibrant or most used color, but the mathematical mean of all the colors it samples.

Q: How accurate is the dominant color detection?
A: The library samples every 10th pixel and averages the RGB values, which provides a good representation of the overall image color. This method works well for images with clear dominant colors but may not capture subtle color variations in complex images.

Q: Can I adjust the sampling rate for better accuracy?
A: The current version uses a fixed sampling rate of every 10th pixel. You would need to modify the source code to change the step value if you require different sampling behavior.

Q: What happens with transparent or mostly transparent images?
A: The library analyzes RGB values but doesn’t account for alpha transparency. Transparent pixels contribute their RGB values to the average, which might produce unexpected results for images with significant transparency.

Related Resources:

• Extracting The Average Color From Images Or Videos – Fast Average Color
• Generate Gradients From Dominant Colors In An Image – Grade.js
• Adaptive Image Background Color – Adaptive Backgrounds
• Extract The Dominant Color of An Image – Primarycolor.js
• jQuery Plugin For Grabbing Image Color – imgcolr
• Image Color Palette Generating Plugin – Color Thief
• jQuery Plugin For Adaptive Image Background Color