An image pick-up apparatus comprising: image shooting means for shooting a subject to generate an input image signal having an image shooting frame rate; main line image processing means for generating a main line image signal having a desired frame rate from said input image signal; and monitor image processing means for generating a monitor image signal having a frame rate independent of said frame rate of said main line image signal from said input image signal; wherein said main line image processing means performs frame addition on said input image signal and switches the number of additive frames in said frame addition, thus generating said main line image signal having said desired frame rate, said frame addition comprising adding together a plurality of frames of said input image signal; the main line image processing means comprising: a plurality of memory elements (414-1, 414-2, 414-3) with an associated input selector (412, 413) and an associated output selector (415, 416) to enable individual memory elements in the plurality to be selected for input and for output; an adder arranged to generate a sum frame by adding a frame of the input image signal to a frame stored in one of the memory elements selected by the output selector; the input selector arranged to select one of the memory elements and to store in that selected memory element either the sum frame or a frame of the input image signal; and the output selector further being arranged to output said main line image signal. image shooting means for shooting a subject to generate an input image signal having an image shooting frame rate; main line image processing means for generating a main line image signal having a desired frame rate from said input image signal; and monitor image processing means for generating a monitor image signal having a frame rate independent of said frame rate of said main line image signal from said input image signal; wherein said main line image processing means performs frame addition on said input image signal and switches the number of additive frames in said frame addition, thus generating said main line image signal having said desired frame rate, said frame addition comprising adding together a plurality of frames of said input image signal; the main line image processing means comprising: a plurality of memory elements (414-1, 414-2, 414-3) with an associated input selector (412, 413) and an associated output selector (415, 416) to enable individual memory elements in the plurality to be selected for input and for output; an adder arranged to generate a sum frame by adding a frame of the input image signal to a frame stored in one of the memory elements selected by the output selector; the input selector arranged to select one of the memory elements and to store in that selected memory element either the sum frame or a frame of the input image signal; and the output selector further being arranged to output said main line image signal. a plurality of memory elements (414-1, 414-2, 414-3) with an associated input selector (412, 413) and an associated output selector (415, 416) to enable individual memory elements in the plurality to be selected for input and for output; an adder arranged to generate a sum frame by adding a frame of the input image signal to a frame stored in one of the memory elements selected by the output selector; the input selector arranged to select one of the memory elements and to store in that selected memory element either the sum frame or a frame of the input image signal; and the output selector further being arranged to output said main line image signal.