There is provided a signal processing apparatus including a first image generating unit, a second image generating unit, a first selecting unit selects at least one of the first image generating unit and the second image generating unit and outputs an image, an image signal processing unit that performs signal processing on the image and outputs the processed image, a second selecting unit that selects one of the first selecting unit and the image signal processing unit and outputs an image, a storing unit that stores information on operations of the second image generating unit and the image signal processing unit, and a third selecting unit that selects at least one of the second image generating unit and the image signal processing unit and connects the selected one to the storing unit, whereby the storing unit is shared between the second image generating unit and the image signal processing unit.