private IcnsHeader readIcnsHeader(final InputStream is) throws ImagingException, IOException {
        final int magic = read4Bytes("Magic", is, "Not a Valid ICNS File", getByteOrder());
        final int fileSize = read4Bytes("FileSize", is, "Not a Valid ICNS File", getByteOrder());

        if (magic != ICNS_MAGIC) {
            throw new ImagingException("Not a Valid ICNS File: " + "magic is 0x" + Integer.toHexString(magic));
        }

        return new IcnsHeader(magic, fileSize);
    }
Constructs a new instance with the big-endian byte order.
src/main/java/org/apache/commons/imaging/formats/icns/IcnsImageParser.java