.img file not read in Snaphu-unwrapping

I am trying to run Snaphu-unwrapping tool after Snaphu Export on .img format of phase file as shown in the screenshot and also in the video (Link: https://www.youtube.com/watch?v=kaZLp8JGlXc) attahced here. However, while giving the phase file in .img format as input to Source Product in Snaphu-unwrapping, it could not read the .img file.