The paper analyzes white-light images of solar granulation taken outside active regions, at regular intervals along the polar axis and the equator, in order to study its center-to-limb variation and possible changes with the solar latitude. The 2D spatial power spectra of the brightness distribution are calculated and corrected for the distortions produced by the atmosphere and the telescope. One-dimensional integrated spectra are obtained for each position, with the geometrical foreshortening effect taken into account. A lower contrast, a smaller mean wavenumber, and a steeper center-to-limb variation of the contrast are found in the central meridian as compared to the equator. Sources of error are discussed, and different scenarios are presented in order to interpret these observational facts. Intensity fluctuations were detected until the extreme limb, with a spatial scale of about 10 arcsec.