There are no images that mimic the color response of the human eye, though you could approximate such an image by combining many images in filters covering the

There are no images that mimic the color response of the human eye, though you could approximate such an image by combining many images in filters covering the visible colors. But they would still not be "unaltered". Astronomical objects have an extremely large dynamic range in terms of brightness. If you've ever looked at a galaxy through a telescope, you'll see what I mean. You just see a blob that's the bright central bulge. The brightness distribution in a galaxy falls off exponentially with radius. If you amplify the signal to see the faint outer parts, the central part would hurt your eyes (or, practically speaking, saturate). We made a movie of a simulated galaxy merger for a competition last year: http://www.youtube.com/watch?v=agqLEbOFT2A http://www.youtube.com/watch?v=agqLEbOFT2A In this rendering, the colors are approximately realistic, but the brightness is not. For my own education, I made an alternative rendering with just a fixed linear stretch that should more realistically (barring monitor gamma) mimic what the eye would see. In that movie (I've been meaning to upload it), you basically only see the centers of the two galaxies, nothing else. So the bottom line is, to see any detail you must "manipulate" these images. It's reminiscent of High-Dynamic Range photography [http://en.wikipedia.org/wiki/High_dynamic_range_imaging http://en.wikipedia.org/wiki/High_dynamic_range_imaging], where you compress the range of brightnesses to be able to convey a scene in one image.