Look closer at the bitsAllocated = 1 case for BigEndian Data.

[suyashkumar]

In #212, the implementation assumes LittleEndian order on reading the data in the code, but the tests with data written out using BigEndian data (written using binary.Write) pass with no issues (perhaps because the reader is BigEndian aware and running on a LittleEndian machine?). Either way, this is a placeholder to remind me to take a closer look at this.