How to use the image-q.utils function in image-q

var num_pixels = width * height;
		
		this.logDebug(6, "Quantizing image", { colors: opts.colors, dither: opts.dither, width: width, height: height, pixels: num_pixels } );
		
		// get rgba pixels from canvas
		var imgData = this.context.getImageData(0, 0, width, height);
		
		// desired colors number
		var targetColors = parseInt( opts.colors || 0 );
		
		if (!targetColors || isNaN(targetColors) || (targetColors < 2) || (targetColors > 256)) {
			return this.doError('quantize', "Invalid palette size: " + targetColors);
		}
		
		// create pointContainer and fill it with image
		var pointContainer = iq.utils.PointContainer.fromImageData( imgData );
		
		// create chosen distance calculator (see classes inherited from `iq.distance.AbstractDistanceCalculator`)
		var distanceCalculator = opts.alpha ? 
			(new iq.distance.EuclideanRgbQuantWithAlpha()) : 
			(new iq.distance.EuclideanRgbQuantWOAlpha());
		
		// create chosen palette quantizer (see classes implementing `iq.palette.IPaletteQuantizer`) 
		var paletteQuantizer = new iq.palette[opts.quantizer](distanceCalculator, targetColors);
		
		// feed out pointContainer filled with image to paletteQuantizer
		paletteQuantizer.sample(pointContainer);

		// generate palette
		var palette = paletteQuantizer.quantize();

		// get color array

images.forEach(image => {

        const imageBuf = image.bitmap.data;
        const inputBuf = new ArrayBuffer(imageBuf.length);
        const inputArray = new Uint32Array(inputBuf);
        for (let bi = 0, ai = 0; bi < imageBuf.length; bi += 4, ++ai) {
            inputArray[ai] = imageBuf.readUInt32LE(bi, true);
        }
        const inputContainer = ImageQ.utils.PointContainer.fromUint32Array(
                inputArray, image.bitmap.width, image.bitmap.height);
        quantizer.sample(inputContainer);
        inputContainers.push(inputContainer);
    });