Robert Simmon provides a hands-on guide to get true color from satellite imagery. The atmosphere makes it a little tricky:
The atmosphere scatters light from the sun before it hits the ground (or a cloud, but we don’t care about those at the moment), and then scatters reflected light again on its way back to a sensor. The atmosphere even scatters light back into a camera that didn’t hit anything on the ground at all.
That would be challenging enough, but the atmosphere changes from one place to another (the air above deserts is typically dry, while the air above a forest is usually moist (even when not cloudy) and often filled with tiny aerosol droplets), and over time (a hazy summer day compared to a crisp fall evening).