An image signal processor, an operating method thereof, and an image processing system are provided. The image processing system includes: a control processor configured to generate and output setting information corresponding to N (where N is an integer of 2 or more) image frames; and an image signal processor configured to perform image processing on the N image frames received from an image sensor based on the setting information, and generate an interrupt signal and transmit the interrupt signal to the control processor based on completion of the image processing performed on the N image frame.