Is there any verifying in the system.img image.

[yushaye]

I have extracted system.img from V8-SCT05.bin(TCL 55V6), and repacked it to the .bin file after modified, but error occured when flashing it.
To locate the question, I have tried to only replace the sparse system.img files and modify the address and offset in header_script ,after all, recaculate two crc32s. But error still appeared when it comes to system.img in the flashimg process.
So I was wondering is there any verifying in system.img and how to manage it?