rowsPerStrip is meant to be a 32 bit unsigned integer, since we store it in an int, and real-world TIFF files use the value 2^32 - 1, it needs to be promoted to a long when calculating tile height with it.
commons/proper/sanselan/trunk/src/main/java/org/apache/commons/sanselan/formats/tiff/datareaders/DataReaderStrips.java