Abstract
This study identifies a previously overlooked peculiarity resulted by the relativistic Doppler effect, suggesting a possible violation of photon energy conservation by a thought experiment. To resolve this, a revised theory is proposed relying on considering fixed intrinsic properties for photons in their rest frame, called the Light Intrinsic Frame of Reference (LIFOR). This theory preserves the constancy of light speed, is fully consistent with special relativity, and explains frequency shifts through Lorentz transformations, leading to a relativistic justification for Planck’s quantization of radiation energy.