RAW文件本身是不可以修改的。Save As 成DNG的时候，META DATA就会指出不是原片。
".... DNG. The format also removes unrecognized metadata from RAW files, making it virtually impossible to retrieve such data from DNG files in the future. Finally, since any alteration is written directly into the DNG file, you have to back up the entire file each time a change is made.".
