Looking for a Node Js developer who can fix the issue am facing with .raw base64string to .bmp base64 string conversion

I have added a pdf here which states exact issue and testapp.zip folder where the codes are . You can find the .raw base64 string in a text file and my present code generate a wrong model of .bmp which u can see in output.bmp. My expectation is i should get a single iris image of 640x480 resolution and 96 dpi when i convert from .raw base64 string to .bmp base64 string. I need the out put in 4hrs