Many visitors ask me for informations about inner format of bitmaps in structure of distributive files with firmware. That is why this rather overloaded page with one big mad sketch is here. If your fw is in file *.xbi instead *.exe, you must to subtract from offsets length of loader code. And if you have other version of fw than 1804, offsets are not valid at all and cyrillic alphabet is propably missing. But naturally - principles are the same.
Firmware is in distributive files divided into blocks with following structure. Every block begins with information about flash address and number of date bytes. Only data bytes are stored into phone. Last check byte of block is computed from all previous bytes using lengthways bit operation XOR.
Reason, why in my example just cyrillic is used, must to be obvious for anyone, who at least on moment choose language C35 at Russian. Cyrillic font "made by Siemens" is really exceptional. If you want, you can to see Siemens' Cyrillic crimes corrected by Anthony.