1. An imaging apparatus, comprising: an image sensor; and signal processing circuitry configured to analyze an output signal from the image sensor and detect a defective pixel included in the image sensor, wherein: the image sensor is configured to input the same subject light on a local area basis via a low-resolution imaging lens with a low optical resolving power for forming an optical image with a resolving power lower than a pixel resolving power corresponding to the pixel density of the image sensor and accordingly acquire an image signal lower than the pixel resolving power corresponding to the pixel density of the image sensor, and output the image signal to the signal processing circuitry, and the signal processing circuitry is configured to compare pixel values of the same color pixels included in the local area on a local area basis including a cluster of the plurality of pixels of the image sensor, and detect a defective pixel based on the comparison result.