Before the digital era and improved light metering, photos would occasionally turn out as too dark or too light.  Those older photos are then digitized with the lighting issues as they were taken.

We can correct most lighting problems using what is called the “Levels Tool”.  This is a tool found in most photoediting programs.  The higher end software apps will have a more sophisticated version of this tool, but for general correction of light, the one in PhotoPea.com works pretty well.

There is just one tutorial for the dark image, but the same principles apply to both types of lighting problems.  Where there is too much “white” in areas of a photo, there is not much pixel data to work with.  Dark photos do tend to be more “editable” in correcting light issues than an overexposed one.