This is loose reasoning - it is true that photons are the same, but completely over simplifies the problem Some addition things worth considering Effective in

This is loose reasoning - it is true that photons are the same, but completely over simplifies the problem Some addition things worth considering Effective intensity of observed object (last I checked, paper isn't a mirror and doesn't reflect very well) Frequency profile of the light being observed (cf light from the sun being imperfectly reflected vs lamp being reflected vs direct light source) Ambient light around observed object which affects both stimulation profile of receptor region of eye AND pupil dilation So yeah original emitter source isn't the only piece of this puzzle