Here we've pulled the Black Point to the right where the histogram starts and pulled the White Point
to the left where the histogram ends.

This adjustment is easier to see if it's done with the Levels command, but I include it here to show
that it can also be done with the Curves command.

This adjustment has given the image a much needed increase in contrast and is the limit of increased
contrast you can get with the Levels command without clipping, but the image needs more contrast and
that is quite simple to do with Curves.

Click 'next' to see increased contrast.