Image processing controller for performing image processing in cooperation with image forming apparatus, image forming system including image processing controller, method of controlling image forming system, and storage medium

An image processing controller capable of preventing an image forming apparatus from being caused to return from a power saving state inefficiently, and wastefully consuming electric power. The controller acquires the status of the apparatus. When the apparatus has received a job in the power saving state, the controller determines whether or not to cause the apparatus to return from the power saving state based on the acquired status of the apparatus. The controller stores the job when there is no need to cause the apparatus to return from the power saving state, and transmits raster image data generated based the stored job to the apparatus when it has returned from the power saving state. When there is need to cause the apparatus to return from the power saving state, the controller transmits raster image data generated based on the received job to the apparatus.