Example (custom GIF header):
GIF89a (47 49 46 38 39 61)
I want to read this file and transfer its hexadecimal content (- ++ pattern)
FHG98` (46 48 47 39 38 60)
File.WriteAllBytes("output.dat", File.ReadAllBytes("input.dat") .Select((b,i)=> (byte)(i%4 < 2 ? b-1 : b+1)) .ToArray());