var canvas = new fabric.Canvas("canvas", {
backgroundColor: "white"
});
fabric.Image.fromURL("https://live.staticflickr.com/65535/51283215722_e949fa76c8_k.jpg", function(img) {
img.filters.push(new fabric.Image.filters.Vibrance({
vibrance: 0
}));
img.filters.push(new fabric.Image.filters.Saturation({
saturation: 0
}));
img.applyFilters()
img.scaleToWidth(350)
img.set({
left: 20,
top: 20
});
canvas.add(img)
}, {
crossOrigin: 'anonymous'
});
function setVibrance(value) {
var img = canvas.item(0);
img.filters[0].vibrance = value;
img.applyFilters();
canvas.renderAll();
}
function setSaturation(value) {
var img = canvas.item(0);
img.filters[1].saturation = value;
img.applyFilters();
canvas.renderAll();
}
(function(global) {
var fabric = global.fabric || (global.fabric = {}),
filters = fabric.Image.filters,
createClass = fabric.util.createClass;
filters.Vibrance = createClass(filters.BaseFilter, {
type: 'Vibrance',
fragmentSource: 'precision highp float;\n' +
'uniform sampler2D uTexture;\n' +
'uniform float uVibrance;\n' +
'varying vec2 vTexCoord;\n' +
'void main() {\n' +
'vec4 color = texture2D(uTexture, vTexCoord);\n' +
'float max = max(color.r, max(color.g, color.b));\n' +
'float avg = (color.r + color.g + color.b) / 3.0;\n' +
'float amt = (abs(max - avg) * 2.0) * uVibrance;\n' +
'color.r += max != color.r ? (max - color.r) * amt : 0.00;\n' +
'color.g += max != color.g ? (max - color.g) * amt : 0.00;\n' +
'color.b += max != color.b ? (max - color.b) * amt : 0.00;\n' +
'gl_FragColor = color;\n' +
'}',
vibrance: 0,
mainParameter: 'vibrance',
applyTo2d: function(options) {
if (this.vibrance === 0) {
return;
}
var imageData = options.imageData,
data = imageData.data,
len = data.length,
adjust = -this.vibrance,
i, max, avg, amt;
for (i = 0; i < len; i += 4) {
max = Math.max(data[i], data[i + 1], data[i + 2]);
avg = (data[i] + data[i + 1] + data[i + 2]) / 3;
amt = ((Math.abs(max - avg) * 2 / 255) * adjust);
data[i] += max !== data[i] ? (max - data[i]) * amt : 0;
data[i + 1] += max !== data[i + 1] ? (max - data[i + 1]) * amt : 0;
data[i + 2] += max !== data[i + 2] ? (max - data[i + 2]) * amt : 0;
}
},
getUniformLocations: function(gl, program) {
return {
uVibrance: gl.getUniformLocation(program, 'uVibrance'),
};
},
sendUniformData: function(gl, uniformLocations) {
gl.uniform1f(uniformLocations.uVibrance, -this.vibrance);
},
});
fabric.Image.filters.Vibrance.fromObject = fabric.Image.filters.BaseFilter.fromObject;
})(typeof exports !== 'undefined' ? exports : this);
<script src="https://cdnjs.cloudflare.com/ajax/libs/fabric.js/4.5.0/fabric.min.js"></script>
<span>Vibrance</span>
<input type="range" value="0" min="-1" max="1" step="0.1" onchange="setVibrance(this.value)"/>
<span>Saturation</span>
<input type="range" value="0" min="-1" max="1" step="0.1" onchange="setSaturation(this.value)"/>
<canvas id="canvas" width="400" height="200"></canvas>