setImageSmoothingEnabled(imageSmoothingEnabled){
        this._imageSmoothingEnabled = !!imageSmoothingEnabled;
        this._updateImageSmoothingEnabled(this.context);
        this.viewer.forceRedraw();
    }
Turns image smoothing on or off for this viewer. Note: Ignored in some (especially older) browsers that do not support this property.

@function
@param {Boolean} [imageSmoothingEnabled] - Whether or not the image is
drawn smoothly on the canvas; see imageSmoothingEnabled in
{@link OpenSeadragon.Options} for more explanation.