You guys are aware that they use 'filters' to take these images, even if you are aware you may not be aware of what filters actually do. If they use a red filter on the images, it doesn't shift all the frequencies of the waves so they coincide as an exact copy just lower down the spectrum, it has a suppression which is a function of the frequency. So if a red filter were used it lowers the intensities of all the other colours, so blue becomes more 'red'. However the filters they use are not purely prime colours, they exist of various spectrum suppression peaks enabling these 'funny' looking images to exist, so I could leave the particular colour of the sky to stay the same but change to colours of all the similar colours lying either side of it in the spectrum, hence 'false colour' image.
Why do they do this? To make it more 'pretty' just why the sun seen in ultraviolet, and gamma observations usually green or purple look much better then the normal looking yellow filters.