out as described later the image data having undergone predetermined data processing is stored in the memory card the dsp 14 is connected to the input block 15 where a user inputs operational commands the input block 15 comprises a release button not depicted a multi functional cross key not depicted a power button not depicted and other buttons the dsp 14 orders each component of the digital camera 10 to carry out a necessary operation according to a user 39 s command input to the input block 15 for example by depressing the release button halfway a first switch not depicted is switched on and an exposure adjustment and focus adjustment are then carried out in the exposure adjustment an exposure value is detected based on the image data and the dsp orders the optical unit driver 18 to adjust the aperture ratio of the diaphragm 16 and the shutter speed accordingly in the focus adjustment the dsp 14 orders the optical unit driver 18 to move the position of the focus lens that is included in the photographic optical system 11 along the optical axis of the photographic optical system 11 further by fully depressing the release button a second switch not depicted is switched on the shutter 17 is driven to open and close and the imaging device 12 is driven to capture a static optical image further by inputting operational commands to the multi functional cross key the iso sensitivity can be adjusted the dsp 14 commences the pixel mixing process based on an operational command to increase the iso sensitivity the pixel mixing process carried out by the dsp 14 is explained below using fig3 and 4 incidentally the dashed double dotted lines drawn in fig4 are border lines among the actual.