An image pickup apparatus, comprising: an image pickup unit including an image pickup element; a first video signal processing unit that generates a first video signal having a first resolution from a pixel signal obtained by the image pickup unit; a second video signal processing unit that downconverts the first video signal generated by the first video signal processing unit to thereby generate a downconverted video signal having a second resolution lower than the first resolution, characterized in that the second video signal processing unit sets respective pixels of 2 horizontal pixels or more × 2 vertical pixels or more including respective pixels of a center portion in a region of 2N horizontal × 2N vertical pixels, N being a power of 2 which is equal to or larger than 2, of the first video signal, which correspond to 2 horizontal × 2 vertical pixels (Y11,Y12, Y21, Y22) of the downconverted video signal, as center portion pixels for said region, calculates luminance representative values respectively corresponding to said 2 horizontal × 2 vertical pixels of the downconverted video signal from luminance values extracted from pixels of said center portion pixels respectively corresponding to said 2 horizontal × 2 vertical pixels of the downconverted video signal, calculates an average value of the luminance representative values, calculates respective values according to pieces of differential data calculated from said average luminance value with respect to said luminance representative values, and individually adds said values according to pieces of differential data respectively to luminance values of corresponding pixels of said 2 horizontal × 2 vertical pixels of the downconverted video signal, to thereby generate a second video signal having the second resolution. an image pickup unit including an image pickup element; a first video signal processing unit that generates a first video signal having a first resolution from a pixel signal obtained by the image pickup unit; a second video signal processing unit that downconverts the first video signal generated by the first video signal processing unit to thereby generate a downconverted video signal having a second resolution lower than the first resolution, characterized in that the second video signal processing unit sets respective pixels of 2 horizontal pixels or more × 2 vertical pixels or more including respective pixels of a center portion in a region of 2N horizontal × 2N vertical pixels, N being a power of 2 which is equal to or larger than 2, of the first video signal, which correspond to 2 horizontal × 2 vertical pixels (Y11,Y12, Y21, Y22) of the downconverted video signal, as center portion pixels for said region, calculates luminance representative values respectively corresponding to said 2 horizontal × 2 vertical pixels of the downconverted video signal from luminance values extracted from pixels of said center portion pixels respectively corresponding to said 2 horizontal × 2 vertical pixels of the downconverted video signal, calculates an average value of the luminance representative values, calculates respective values according to pieces of differential data calculated from said average luminance value with respect to said luminance representative values, and individually adds said values according to pieces of differential data respectively to luminance values of corresponding pixels of said 2 horizontal × 2 vertical pixels of the downconverted video signal, to thereby generate a second video signal having the second resolution.