With the success of the Event Horizon Telescope, identifying new observational signatures of black holes are of increasing interest. In this talk we investigate blueshift of photons from an equatorial accretion disk of emitters orbiting on stable circular orbits terminating at the ISCO (innermost stable circular orbit). We analytically calculate the blueshift of photons that escape to the celestial sphere (instead of falling into the black hole) and numerically calculate the maximum blueshift received by an observer at fixed angle on the celestial sphere.