&gt; <i>However real black and white photos represent the actual intensity of the light waves</i><p>No. Black and white negatives represent the intensity of the light (possibly with some lens filters in between) multiplied by some light frequency sensitivity distribution of the film, under some nonlinear time&#x2F;intensity response function composed with another nonlinear time&#x2F;chemical strength&#x2F;exposure function from the chemical development of the negative.<p>Then to get from negative to print, black and white photos undergo another pair of multiparameter nonlinear functions (representing the exposure and chemical development process), possibly including intentional manipulation by a human operator.<p>Depending on the film, filters, development process, and printing techniques used, this can be relatively close or quite far from a naively converted 3-channel color picture.<p>For details cf. for example Ansel Adams’s books <i>The Negative</i> and <i>The Print</i>.