Hi Francois,
I am very grateful for your kind help. As there are two ways to get the ImageGridAmp data, I tried both of them.
Firstly, I tried to get the full source maps including ImageGridAmp in Brainstorm, and error reported: "index exceeds matrix dimensions". The details are shown in the picture below.

Secondly, I followed the step you put forward in another posts to calculate the ImageGridAmp using imagekernel, which is shown below.
- Right-click on the file to load > File > Copy file path to clipboard
- In the Matlab command window: ResultsFile = '....paste the file path with CTRL+V...';
- ResultsMat = in_bst_results(ResultsFile, 1);
Then Error message returned: "Cannot use this operation on source files attached to continuous RAW files."
In my case, the source data is sLORETA:MEG(Unconstr). What's wrong with my data and procedure? Just let me know if you need more details. I am so sorry for keeping bothering you and thanks very much for your time.
Best,
Junjie Ma
