rescale(pixelData) {
        for (let i = 0; i < pixelData.length; ++i) {
            pixelData[i] = this.rescale_factor * pixelData[i];
        }
    }
Rescale the image' pixel values by `this.rescale_factor`.
@param {Float32Array} pixelData The pixel data to rescale.
@returns {void}