import OpenImageIO
exr_filPath = 'x:/project/testfolder/testImage.exr'
def edit_exr( exr_filPath):
#renames Channels
newimg = OpenImageIO.ImageBuf(exr_filPath)
#adds metadata
newimg.specmod().attribute("subRound","r2")
newimg.specmod().attribute("nukeRef","0000")
#writes image
newimg.write(exr_filPath)