Complex sentence: Some digital SLRs have systems that remove dust from the sensor by vibrating or knocking it, sometimes in conjunction with software that remembers where dust is located and removes dust-affected pixels from images.
Split into simpler sentences: Some digital SLRs however, have systems that remove dust from the sensor by vibrating or knocking the sensor. Some cameras do this in conjunction with software that remembers where dust is located on the sensor and removes dust-affected pixels from images.