processImage(processor, size, quality) {
    let canv = BunnyImage.cropByCursor(this.UI.getImage(processor), this.UI.getCursor(processor));
    canv = BunnyImage.resizeCanvas(canv, size);
    const base64 = canv.toDataURL('image/jpeg', quality);
    return base64;
  }
Process an image - crops by selected region, resize to $size x $size
makes an image/jpeg with $quality
and returns a base64 string can be used in src attribute or for further custom file processing

@param processor
@param size
@param quality
@returns {string}