Just as the intensity of the light from a candle decreases with distance, I would expect the light from the sun to illuminate the distant planets less than the closer ones. However, the pictures of Pluto from New Horizons don't seem any "darker" than those of the other planets. Have the photos been edited in some way to correct for the lower light? Or is there something else going on? My first thought was that this problem could be solved with longer exposure for each image, but I imagine that would cause blur problems given the speed of the probe.
It's brighter on Pluto than you think.
NASA developed a tool called Pluto time, which tells you when at your place the ambient light conditions are similar to the ones on Pluto. This occurs when the Sun is only 2° below the horizon! That's quite shortly after sunset, and considerably before the end of civil twilight, which is when it's 6° below.
All of these photos were taken at local "Pluto time":
Pluto time, according to NASA. Source: NASA
To answer your question: all it takes is a slightly longer exposure time / larger aperture than taking photos closer to the Sun. It's easily bright enough for outdoor activities, so have fun glacier hiking on Pluto!