fled.js

var paper = Raphael(0, 0, 400, 400);

var r  = 100;
var steps = 120;
var totLed = 48;
// Sets the fill attribute of the circle to red (#f00)
var circles =  [];
// Sets the stroke attribute of the circle to white

var alpha = 0;
var offsetX = 200;
var offsetY = 200;
for(var i = 0; i < 5700; i++) {
    
    if(i!=0 && i%totLed == 0) {
        alpha = (alpha+1)%steps;
    }
    var x = 4 * (totLed - (i%totLed)) * Math.cos(2*Math.PI/steps * alpha);
    var y = 4 * (totLed - (i%totLed)) * Math.sin(2*Math.PI/steps * alpha);
    
    var circle = paper.circle(x + offsetX,y + offsetY,2);
    circle.attr("fill", "#000");
    circle.attr("stroke", "transparent");
    circle.hover(function(e,a){
        this.attr("fill","#0f2");

        //e.toElement.attr("fill","#000");

    });
    
    circles.push(circle);    
    
}

function printBuffer() {
    console.log(circles.map(function(item){
        return (item.attr("fill") == "#000") ? 0 : 1;
    }));
}

window.printBuffer = printBuffer;

index.html

<button onClick="printBuffer()" style="position:absolute; bottom:0;">Press</button>