We all know that some parts of the images that NASA, and any space agency shows us are "fake." Not fake as in they were made in a facility in Arizona, but painted with colors other than the ones that were collected, omitting some bits of information and emphasizing others. We'll take a quick look at how partially fake pictures can be better than real ones.
Today, a great many people are going to be looking at images from Mars from the Curiosity rover. For the past few years, NASA has shown us images and even videos from the Opportunity rover. Much oohing and ahhing has been done, and all of it deserved. Yet in most comment sections of most sites you will see a few people talking about the tinting of the pictures, or the outright fakery of the pictures. Some of these come from outright conspiracy theorists. Some come from people who are part of the ongoing debate about how much artistry goes into each picture.
There was a minor furor in 2004 when a New Scientist article raised questions about the true color of Mars. Accusations of NASA tinting the pictures it got from Mars to make it look more like the Red Planet of legend (and some said, to conceal green evidence of Martian life) flew. It turned out to be a simple filtering mix up. The Mars rover used green, blue, and red filters to approximate colors as people would see them. The red filter, however, was usually a waste of time, since their was little green or blue on Mars. There were some on the space craft that had landed, though, as so when the rover used green, blue, and infrared filters, the blues and the greens looked reddish, and people saw the entire picture as "fake." As any color-blind person knows, however, just because you see one color incorrectly, doesn't mean you see them all incorrectly.
And correct is a subjective term anyways. Anyone with a camera, even an amateur taking vacation photos, knows what a change of lighting can do to colors on a picture. No one looks at a regular photo and declares it fake because a shirt that they see as blue in regular life looks black in a photo. Even two live people will disagree on a color, as anyone who has pointed to a wall and declared it blue only to have their friend say it's green knows perfectly well. The task of taking in information and making an accurate photographic image is tougher than we like to let on.
What's more, the infrared filter wasn't used for no reason. It was used to help geologists know what types of rocks were where, and what types of debris were on each rock. Filtered images, then, might not let people know about the exact shade of red that the red planet is, or the colors of the space craft, but do let people see geological conditions on Mars that they would otherwise miss. Mixing together different filters, then, doesn't force people to choose between a true and a false image, but between two images, each of which show accurate information.
And sometimes, accurate information can't be shown any other way than with false colors. Astronomers observe visible light, sure, but they also look at ultraviolet, infrared, and radio waves, none of which can be seen by humans, but all of which can be translated into visible light. At first, these images are often rendered in black and white, but to make them both dramatic and clear, they're translated into color. This is hardly faking anything. Radio transmissions aren't any color, so making them look good in vivid colors isn't any more false than giving people a bland black and white image. Coloration - like that on the satellite above in which the red shows old rock and the blue new terrain - can highlight features that people otherwise wouldn't see.
In the end, artistry goes into any picture that we see, be it painted or pixelated. As long as it's clear what we're seeing, emphasized or even truly false colors can show us things we never would have noticed otherwise - which, when you think about it, is why we developed a color sense in the first place.
Gorgeous pictures of Mars are all over the place, but if you want to see a Martian sunset (shot with two different filters to determine exact color), and find out why Martian sunsets are blue while regular Martian skies are pink, check out this week's io9 show!
Top Image: NASA, ESA and J. Hester (ASU)
Viking: San Diego Air and Space Museum