byte[] gbuf = new byte[ (int)gl ];
long gl2 = lut.GetLUT( LookupTable.LookupTableType.GREEN, gbuf );
assert gl == gl2;
long bl = lut.GetLUTLength( LookupTable.LookupTableType.BLUE );
byte[] bbuf = new byte[ (int)bl ];
long bl2 = lut.GetLUT( LookupTable.LookupTableType.BLUE, bbuf );
assert bl == bl2;
colorModel = new IndexColorModel(8, (int)rl, rbuf, gbuf, bbuf);
// For code below
imageType = BufferedImage.TYPE_BYTE_GRAY;
}