Besides providing information about position and orientation of the camera IMU will be responsible for correcting ERS distortion when the camera is moving fast or rotating and images will be scewed. Sensor with Electronic rolling shutter as evident from it's name doesn't take a snapshot image but scans lines one by one like a scanner. This is why we see such distortion in a fast moving object, or when the camera is moving. Since the IMU takes about 2500 samples per second and image sensor scans about 2000 lines in 15 miliseconds, every 50th line is tagged with IMU measurment. This way we can compensate for the ERS distortions when camera is moving fast in the post-processing knowing position and orientation of the camera at each 50th line of the image scan.