1. A sky camera system, comprising: an objective lens having a field of view of greater than or equal to 170 degrees; a spatial light modulator at an image plane of the objective lens, wherein the spatial light modulator is programmable and is configured to attenuate light from objects including direct sun in images captured by the objective lens such that the sky camera system is configured to obtain sky images including an image of the sun; at least one anti-blooming semiconductor image sensor behind the spatial light modulator; and one or more relay lenses, between the spatial light modulator and the anti-blooming semiconductor image sensor, configured to project the images from the spatial light modulator to the anti-blooming semiconductor image sensor, wherein the spatial light modulator is configured to attenuate the image of the sun such that the image of the sun can fit into a dynamic range of the anti-blooming semiconductor image sensor, and wherein a response of the sky camera system, prior to field operation, has been calibrated indoors using a calibration light source of known radiation intensity with the spatial light modulator set to transparent, and wherein the sky camera system is free of a mechanical sun blocker and thus can obtain a complete sky image.