Image Transmutation 🧙💫

This is a helper script built with NodeJS that automatically converts and resizes your images based on the given arguments. It uses Sharp to do the necessary conversions.

It is usable via command line, so you can add it to your package.json scripts after installing the NPM package.

I have written a blog post about optimizing images, which includes usage of this script, if you'd like to read more about use cases for it.

Why transmutation? Transmutation is the action of altering the properties of an object or being (or an image file). It is also a school of magic in many fantasy universes! 🎲

Installation

Simply run

npm install -D image-transmutation

to install it as a development dependency on your project.

How to use

1. Once you install the NPM package, you can use it with the image-transmutation command.
2. I recommend adding it to your package.json scripts, like so:

"scripts": {
  "optimize-images": "image-transmutation --run --sourceFolder \"./source\" --targetFolder \"./target\" --inputFormats \"jpg\" --inputFormats \"jpeg\" --inputFormats \"png\" --outputFormats \"webp\" --outputFormats \"avif\" --widths 500 --widths 1000 --enlarge"
}

3. Run npm run optimize-images to execute the script.
4. You can add it to a "postbuild" script, so it runs automatically after your build process.

Available arguments

  --help, -h        Displays this help text

  --run, -r         Executes the script
    --sourceFolder      REQUIRED - The relative or absolute path to the folder where the images currently are.
    --targetFolder      REQUIRED - The relative or absolute path to the destination folder where the converted images will be saved at. Warning: all contents in the folder will be deleted prior to execution.
    --inputFormats      REQUIRED - The existing formats that the script will look for, like jpg and png.
    --outputFormats     REQUIRED - The formats the script will convert to.
    --widths            Optional - The widths to which the images will be resized to. If not declared, images will be kept at their original size.
    --enlarge           Optional - Defines if images should be enlarged in case their original width is smaller than the target size defined on --widths.
    --clearTarget       Optional - Defines if the targetFolder should be cleared (all files deleted) before the optimization runs.

Example command

This command runs using the folders built-in to this repository. It takes jpg, jpeg and png images and converts them into webp and avif, with widths of 500px and 1000px.

image-transmutation --run --sourceFolder "testing-room/source" --targetFolder "testing-room/target" --inputFormats "jpg" --inputFormats "jpeg" --inputFormats "png" --outputFormats "webp" --outputFormats "avif" --widths 500 --widths 1000 --enlarge

As a result:

/testing-room
  /source
    fluid.png

generates

/testing-room
  /target
    fluid-500w.avif
    fluid-500w.webp
    fluid-1000w.avif
    fluid-1000w.webp