$TileData is still a string instead of a number, so it doesn't work with the bitwise operators.
Well, of course it doesn't since my suggestions related to the file handling aspects of your code only (as I thought I made clear in my original response) because BrowserUk had already answered the bitwise operator aspects of your problem. Please re-read his answer and study the documentation for pack and unpack then show us your code and explain precisely why it doesn't do what you want it to.

In reply to Re^5: Question about binary file I/O by eyepopslikeamosquito
in thread Question about binary file I/O by TheMartianGeek

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