HTML5 Canvas RGB filter Image Tutorial

To apply filter to an Konva.Image, we have to cache it first with cache()
function. Then apply filter with filter() function.

To change rgb components of an image with Konva, we can use the `Konva.Filters.RGB.

Instructions: Slide the controls to change rgb values.

For all available filters go to Filters Documentation.

Konva RGB Image Demoview raw
<!DOCTYPE html>
<html>

<head>
<script src="https://cdn.rawgit.com/konvajs/konva/2.1.3/konva.min.js"></script>
<meta charset="utf-8">
<title>Konva RGB Image Demo</title>
<style>
body {
margin: 0;
padding: 0;
overflow: hidden;
background-color: #F0F0F0;
}

#controls {
position: absolute;
top: 20px;
left: 20px;
}
</style>
</head>

<body>
<div id="container"></div>
<div id="controls">
Red:
<input id="red" type="range" min="0" max="256" step="1" value="150"> Green:
<input id="green" type="range" min="0" max="256" step="1" value="150"> Blue:
<input id="blue" type="range" min="0" max="256" step="1" value="150">
</div>
<script>
Konva.Image.fromURL('../../../assets/lion.png', function (lion) {
var stage = new Konva.Stage({
container: 'container',
width: window.innerWidth,
height: window.innerHeight
});

var layer = new Konva.Layer();

lion.position({
x: 50,
y: 50
});
lion.cache();
lion.filters([Konva.Filters.RGB]);
layer.add(lion);
stage.add(layer);

var sliders = ['red', 'green', 'blue'];
sliders.forEach(function (attr) {
var slider = document.getElementById(attr);
function update() {
lion[attr](parseFloat(slider.value));
layer.batchDraw();
}
slider.oninput = update;
update();
});
});
</script>

</body>

</html>