Learn how to generate an ascii art photo live with your camera web

How to generate an ascii art photo from the webcam with Javascript

Camera ASCII

Camera ASCII uses the HTML5 getUserMedia API to transform a video stream from your webcam into a real-time ASCII representation. You can use the library without camera, you can generate the same effect drawing a image on a canvas.

The demo works using 2 plugins, camera.js (a wrapper to get acces to the camera and display it on a canvas) and ascii.js, the most important piece of the demo. ascii.js is a tiny library that converts a canvas image to an art string.

How does it works

The library returns a global object named ascii , this object has only 1 property "fromCanvas". This function expects as first parameter the canvas which is going to be processed and as second parameter an object with the properties.

var canvas = document.getElementById("myCanvasId");
ascii.fromCanvas(canvas, {
     callback: function(asciiString) {
        // Do something with the asciiString
     }
});

The library will use the following characters in the ascii string ".,:;[email protected]".

var characters = (" .,:;[email protected]").split("");
var context = canvas.getContext("2d");
var canvasWidth = canvas.width;
var canvasHeight = canvas.height;
		
var asciiCharacters = "";

// calculate contrast factor
// http://www.dfstudios.co.uk/articles/image-processing-algorithms-part-5/
var contrastFactor = (259 * (options.contrast + 255)) / (255 * (259 - options.contrast));

var imageData = context.getImageData(0, 0, canvasWidth, canvasHeight);

Then it will use a loop with the retrieved pixel data using the getImageData function from the canvas and according to the brightness of every pixel (Color brightness is determined by the following formula: ((Red value X 299) + (Green value X 587) + (Blue value X 114)) / 1000) a character from the characters variable will be choosen to be drawn (appended to the asciiCharacters variable).

Note: the contrast of the image will be changed to get a better result, you can increment the contrast using the contrast parameter in the fromCanvas function.

Demo

You can test a live version from the plugin here.

Ascii camera demo

Note that you can use css to customize and give curious effects to the image. The previous image has been rendered using css : color:blue; to the pre element.

You can customize to changing the characters that are being rendered, for example :

Ascii color css

The previous image has been achieved changing the characters line in the ascii.js file:

var characters = {
        0:'<span style="background-color: yellow;"> </span>',
        1:".",
        2:",",
        3:":",
        4:";",
        5:"i",
        6:"1",
        7:"t",
        8:"f",
        9:"L",
        10:"C",
        11:"G",
        12:"0",
        13:"8",
        14:'<span style="color: red;">@</span>'
}

Note that the performance will decrease noticeably if you're using the camera instead of a image on a canvas.

Requirements

  • Your navigator needs to provide support for getUserMedia API
  • https connection as insecure connections doesn't allow access to the API

Have fun !


Interested in programming since he was 14 years old, Carlos is a self-taught programmer and founder and author of most of the articles at Our Code World.

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