There's a guy named Joseph Skipper who runs a site called Mars Anomaly Research.
http://www.marsanomalyresearch.com/
It's basically a crank website which claims that NASA and the ESA have been doctoring space image data for many years, in an attempt to cover up the truth: that Mars and other bodies in the solar system are actually much more similar to the Earth than we are being told. The guy running it believes that Mars, the Moon, and various moons of outer planets are inhabited by a wide variety of alien lifeforms, including several advanced civilizations. The bulk of his "evidence" consisted of weirdly-shaped shadows which, with the right brightness/contrast settings manipulated in Photoshop, look exactly like farms, buildings, giant (we're talking miles wide) trees, or deliberate airbrushing of key features by the evil scientists. Skipper's theories are based on the premise that no information gathered by space probes is passed to the general public without inspection by "the authorities," who censor and obfuscate all evidence which contradicts their "illusion" of desiccated, cold, empty worlds. Of course, how they could keep such a scheme secret is never examined in detail.
Yup. Zoom in on a lossy jpeg and you will find all the wonders of the universe...if you let your imagination run riot.