The "JavaScript Image Manipulation Program" :-)
An image processing library written entirely in JavaScript for Node, with zero external or native dependencies.
Example usage:
var Jimp = require("jimp"); // open a file called "lenna.png" var lenna = new Jimp("lenna.png", function () { this.resize(220, 220) // resize .write("lenna-small.png") // save .quality(60) // set JPEG quality .write("lenna-small.jpg") // save as JPEG .greyscale() // set greyscale .write("lena-small-bw.png") // save again .crop(80, 100, 80, 50) // crop .write("lena-small-bw-cropped.png"); // save again }); The Jimp constructor takes two arugments, the path to a JPEG or PNG image and an optional call back for when the image is parsed:
var image = new Jimp("./path/to/image.jpg", function () { // ready }); Once the callback has fired the following methods can be called on the image:
image.crop( x, y, w, h ); // crop to the given region image.invert(); // invert the image colours image.greyscale(); // remove colour from the image image.sepia(); // apply a sepia wash to the image image.opacity( f ); // apply an opacity of 0-1 to the image image.resize( w, h ); // resize the image image.scale( f ); // scale the image by the factor f image.blur( r ); // fast blur the image by r pixels image.gaussian( r ); // Gaussian blur the image by r pixels (VERY slow) (Contributions of more methods are welcome!)
The image can be written to disk in JPEG or PNG format using:
image.write( path, cb ); // callback will be fired when write is successful The quality of saved JPEGs can be set with:
image.quality( n ); // set the quality of saved JPEG, 0 - 100 The library enables low-level manipulation of images in memory through the bitmap property of each Jimp object:
image.bitmap.data; // a buffer of the raw bitmap data image.bitmap.width; // the width of the image image.bitmap.height // the height of the image This can be manipulated directory, but remember: garbage in, garbage out.
A helper method is available to scan a region of the bitmap:
image.scan(x, y, w, h, cb); // scan a given region of the bitmap and call cb on every pixel Example usage:
image.scan(0, 0, image.bitmap.width, image.bitmap.height, function (x, y, idx) { // x, y is the position of this pixel on the image // idx is the position start position of this rgba tuple in the bitmap buffer var red = this.bitmap.data[idx]; var green = this.bitmap.data[idx+1]; var blue = this.bitmap.data[idx+2]; var alpha = this.bitmap.data[idx+3]; // rgba values run from 0 - 255 // e.g. this.bitmap.data[idx] = 0; // removes red from this pixel }); Jimp is licensed under the MIT license.