@hamer1952:
I think what it also means is that you can load a photograph (or any image) and with the proper setting can run the empty brush over it and it picks up the colors and values from the source image thus giving the surface a painterly feel.
Many people have used that feature for various looks. It most often retains the character of the photograph which can be satisfying when painting something beautiful as with a model's portrait. In those cases, selection of a good source photo is critical because if one were to use a drab photo it's likely the painting would also be drab because the photo is also the palette. On the other hand, one can embellish and actually use new colors on it if desired.
I forgot what the actual procedure is but clearly there are those who use it and could tell you.
"Not a bit is wasted and the best is yet to come. . ." -- remembered from a dream