trim-image-data

Function for trimming surrounding pixels of an ImageData-instance.

Usage no npm install needed!

<script type="module">
  import trimImageData from 'https://cdn.skypack.dev/trim-image-data';
</script>

README

trim-image-data

💇‍♀️ Function for trimming/cropping transparent pixels surrounding an image. Very similar to trim-canvas, but accepts and returns an ImageData-instance instead. Also allows specifying custom colors to trim.

Demo

https://trim-image-data.netlify.app

Installation

npm yarn
npm install trim-image-data yarn add trim-image-data 

Usage

trimImageData(imageData, trimOptions)

Creates a trimmed version of an ImageData-instance. Trims fully transparent pixels by default. Does not mutate the recieved instance.

Parameters:

  • imageData - the ImageData-instance instance to crop

  • cropOptions - optional, an object specifying the amount of pixels to crop from each side

    • trimColor({ red, green, blue, alpha }) => boolean
      Callback function used to determine if a value should be trimmed or not. Receives an object of RGBA channels and should return a boolean.

Return value:

A new, trimmed ImageData-instance.

Examples:

import trimImageData from 'trim-image-data';

// trim surrounding fully transparent pixels
const trimmedTransparent = trimImageData(imageData);

// trim surrounding white pixels
const trimmedWhite = trimImageData(imageData, {
  trimColor: ({ red, green, blue, alpha }) => {
    return red === 255 && green === 255 && blue === 255 && alpha === 255;
  };
});

// trim any pixel without max alpha
const trimmedDim = trimImageData(imageData, {
  trimColor: ({ alpha }) => alpha === 255
});

Related packages

  • crop-image-data - crops ImageData by specified number of pixels. Used as a dependency in trim-image-data.

Credits

A lot of the code in this repo is based on trim-canvas, I just had a need for the same functionality without passing a canvas.