How do I allow insert picture in sheet when it is protected
 

I want to create a template and distribute it to employees wherein I want
some cells to be non editable. Hence I lock concerned cells and then protect
worksheet.
But then I want this file back from them after filling in required details
and inserting their scanned signature at bottom.
Here once sheet is protected, cannot insert picture from file even in
unlocked cells.
I have to tell them to copy and paste the picture wherein I want them to
insert picture.
How do i do it?