I found Arduino don't accept long string format like "ABC\x00\x01....", but accept array like: {65,66,67,0,52,...}, the first 2 bytes are the data length in INT, so the total length of array is data length+2. The output format can be copy->paste to new welcome screen and micro commands data on Digole COLOR OLED module, this module not only accept bitmap but also accept all internal commands in welcome screen data. This tool also can convert binary file to string/array, and array to string/binary file
Load Binary File:

C format string Input/Output

C array Input/Output (Dec)