Can you run the example code the ENVIGainOffsetRaster help? https://www.harrisgeospatial.com/docs... If it works for the example file, can you tell me what sort of file you are trying to add gain/offset information? Is it an ENVI format file or another file type? This information can only be written to ENVI format files in the .hdr.

I ran it's example and it is done but when I opened metadata file for output I saw that there is not any coefficient for gains and offsets. And also when I run it's code for another data, this situation happens for them. Do you have any suggestion for solve this problem? could you help me please? because this code is very very applicable and useful. thanks for your attention.