In the mid-to-late 19th century, inventors began experimenting with ways to record real colour — not just black-and-white or hand-tinted images. Encyclopedia Britannica+2National Science and Media Museum+2 There is also a good history at this link Science and Media Museum

One of the first workable methods was the “three-colour separation” technique, first demonstrated publicly by James Clerk Maxwell in 1861: a subject (often a simple object like a tartan ribbon) was photographed three times, each exposure made through a different colour filter — red, green, and blue. Wikipedia+2Wikipedia+2

Later pioneers — such as Louis Ducos du Hauron and John Joly — refined the idea: in Joly’s process, for example, a specially prepared glass screen marked with very fine red, green, and blue lines was placed in front of the photographic plate during exposure. After development, the resulting black-and-white transparency could be viewed in register with a matching screen, producing a rudimentary colour image. Wikipedia+1

These early colour experiments had major limitations: photographic materials of the time were often insensitive to large portions of the colour spectrum, exposures were long, and colours tended to be imperfect or muted. Encyclopedia Britannica+1

Nevertheless — as historians like those who contributed to The Daguerreotype in America document — these experiments laid the scientific foundation for what would later become more reliable and commercially viable colour photography in the 20th century.