Image pickup apparatus and image pickup apparatus control method that generates an image with transformed number of pixels

An image pickup apparatus control method executed in an image pickup apparatus, the control method comprising:

• a pixel addition signal output step of outputting, in a pixel unit, a pixel addition signal obtained by adding output pixel signals from pixels having different sensitivities to each other;
• and
• a pixel information synthesis step of executing, in a pixel information synthesis unit, a weighted addition processing of multiplying plural pixel addition signals output from the pixel unit by a previously set gain and calculating a configuration pixel value of a pixel number reduction image where a total number of pixels is lower than a number of pixels of the pixel unit,
• wherein a control on gravity center positions for respective pixels constituting the pixel number reduction image is executed through the pixel addition signal generation processing by the pixel unit and the weighted addition processing by the pixel information synthesis unit.