Img files extracted from the firmware after modified, once again after packaging binwalk found less a uImage header, the second original img file uImage what is the role of the header? How should generate


The modified img
0 0 x0 uImage header, the header size: 64 bytes, the header CRC: 0 xcf874149, created: the 2019-04-16 17:01:54, image size: 159744 bytes of Data Address: 0 x18a0000, Entry Point: 0 x1970000, Data CRC: 0 xd71c59f4, OS, Linux, CPU: ARM, image type: Standalone Program, compression will type: none, image name:
"custom"64 0 x40 Squashfs filesystem, little endian, version 4.0, compression will: xz, size: 157085 bytes, 10 inodes, blocksize: 1048576 bytes, created: the 2019-04-16 17:01:54

Before modifying img
0 0 x0 uImage header, the header size: 64 bytes, the header CRC: 0 x60f68522, created: the 2019-03-25 10:33:43, image size: 75960 bytes of Data Address: 0 x18a0000, Entry Point: 0 x1970000, Data CRC: 0 x1a0e8440, OS, Linux, CPU: ARM, image type: Standalone Program, compression will type: none, image name:
"custom"64 0 x40 Squashfs filesystem, little endian, version 4.0, compression will: xz, size: 70161 bytes, 6 inodes, blocksize: 1048576 bytes, created: the 2019-03-25 10:33:43
73816 x12058 uImage header, the header size: 64 bytes, the header CRC: 0 x597f1585, created: the 2019-03-25 10:33:43, image size: 73728 bytes, the Data Address: 0 x18a0000, Entry Point: 0 x1970000, Data CRC: 0 xb70de304, OS, Linux, CPU: ARM, image type: Standalone Program, compression will type: none, image name: "custom"