1. An imaging apparatus, comprising: a solid-state image sensor in which a plurality of imaging pixel blocks and a plurality of focusing pixel blocks are disposed in a two-dimensional pattern, and that executes photoelectric conversion for a subject image formed through an optical system, each of the imaging pixel blocks including a plurality of imaging pixels that output imaging signals, the imaging pixels being disposed in a two-dimensional pattern, each of the focusing pixel blocks including at least one of the imaging pixels and a plurality of focus detection pixels that output focus detection signals, the at least one of the imaging pixels and the focus detection pixels being disposed in a two-dimensional pattern; an image processing unit that obtains an image signal regarding each of the imaging pixel blocks and an image signal regarding each of the focusing pixel blocks and generates an image data based on the image signals regarding the imaging pixel blocks and the image signals regarding the focusing pixel blocks; a focus detection unit that detects a focusing condition based upon the focus detection signals output from the focus detection pixels and outputs a detection signal; and an adjustment unit that executes focus adjustment for the optical system based upon the detection signal provided from the focus detection unit, wherein: the imaging pixels output the imaging signals obtained through photoelectric conversion executed on a light flux received from an area of an exit pupil of the optical system, which is substantially not offset from a center of the exit pupil; the focus detection pixels output the focus detection signal obtained through photoelectric conversion executed on a light flux selectively received from an area of the exit pupil of the optical system, which is substantially offset from the center of the exit pupil; imaging pixel blocks and the focusing pixel blocks each include m×n pixels disposed in a two-dimensional pattern with m pixels and n pixels among the plurality of pixels set respectively along a columnar direction and along a row direction, where m and n each represent an integer equal or greater than 2; color filters having a single color being disposed at the imaging pixels belonging to a each of the respective imaging pixel blocks; and the image processing unit obtains the image signal regarding each of the imaging pixel blocks based upon the imaging signals output from the imaging pixels disposed in the respective imaging pixel blocks, and obtains the image signal regarding each of the focusing pixel blocks by executing an interpolation process based upon the imaging signals output from at least one of the imaging pixels in the respective focusing pixel blocks and the focus detection signals output from at least one of the focus detection pixels in the respective focusing pixel blocks.