public void unsetBitShift() {
            bitShiftSet = false;
        }
Suppresses the setting of the bit shift of a grayscale image.
Pixels in the source image will not be shifted prior to encoding.
plugins/svg-plugin/batik-codec-fix/src/main/java/org/apache/batik/ext/awt/image/codec/png/PNGEncodeParam.java