Planck said that "energy of photon is quantized. That means energy of a photon cannot be any random value but a certain values only".
If this is true how electromagnetic spectrum is continuous. For example, we know that spectrum of visible light is continuous but this implies that visible light can have all frequencies between red and violet and this again implies that photons can have all energy values between energy of red light and energy of violet light. But isn't contradictory to Planck's theory that energy of photon can only take discrete values.