The GeoEye-1 satellite has the high resolution imaging system and is able to collect images with a ground resolution of 0.41 meters (16 inches)
How about Mars then? From all the Mars orbiter's cameras, which one has the highest resolution?
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The highest resolution images come from the HiRISE camera on the Mars Reconnaissance Orbiter. With an angular resolution of one micro-radian it has a ground resolution of about 0.3 m (12 inches)
Here's an image of the Phoenix lander on its parachute, at a resolution of about 30cm taken from https://static.uahirise.org/images/2008/details/cut/PSP_008579_9020_cut.jpg
(By the way, I'm sure there are satellites orbiting Earth with better resolution. But the US and Soviet military don't share the images from their spy satellites publically)
@JamesK's answer indicates that HiRise is the "highest resolution camera on a Mars orbiter" but it's worth noting that it is also (at least currently) the highest resolution known, human-built camera anywhere in deep space!
@Phiteros' answer to What's the largest aperture telescope sent beyond the Earth-Moon system? begins:
After looking through various mission articles on Wikipedia, the Mars Reconnaissance Orbiter's HiRISE camera has an aperture of 19.7 inches (50 cm), which Wikipedia claims is "the largest so far of any deep space mission". This camera allows it to take extremely detailed pictures of the surface.