The Real Reason NASA Frequently Alters Its Photos

Mars: Our closest planetary neighbor and home to red dunes and barren red rock. Or is it yellowish-brown dunes and rock? Or grayish-blue? Well, that’s just it: No human has ever been to Mars, so there’s no default “correct” Martian landscape colors. Humans see green, blue, yellow, red — whatever — through Earth’s atmosphere and light. And even then, colors change depending on the amount of light, atmospheric haze, the individual eyes of the viewer, etc. And fun fact: NASA’s Martian rovers aren’t equipped with human eyes. 

Looking at raw, calibrated, and white balanced photos side by side illustrates this point perfectly — a point that explains how and why NASA alters photos. Raw photos are unprocessed versions similar to the amassed data of digital cell phone pictures. Images taken by the Mars Curiosity rover, for example, appear yellowish. But those colors aren’t what Mars would look like to a person on Mars. For that we look to the calibrated photos, which show a redder version of the planet. But it’s the white balanced pictures — a term that should be familiar to photographers, video editors, and Photoshop users — that produce the sharpest photos because they adjust all colors in reference to true white. This makes the images look the closest to an Earth-like illumination. Which is the “correct” photo? All of them. Other raw NASA photos from the Mars rover Perseverance, it should be noted, are completely gray.