public void setBitDepth(int bitDepth) {
            if (bitDepth != 8 && bitDepth != 16) {
                throw new RuntimeException();
            }
            this.bitDepth = bitDepth;
            bitDepthSet = true;
        }
Sets the desired bit depth for an RGB image.  The bit
depth must be 8 or 16.
plugins/svg-plugin/batik-codec-fix/src/main/java/org/apache/batik/ext/awt/image/codec/png/PNGEncodeParam.java