Hi Bob,
Duped background and ran "Find Edges"
Desaturated the line drawing (Find Edges) then buzzed this layer
Set this layer at Soft Light with Opacity at 88%
Duplicated the background again and ran buzz again.
You should now have 3 layers stacked from top down
1. Sketch Layer
2. Copy of background buzzed - This is going to be your "history" layer.
3. Original Background
Now to paint with the history brush, Select the buzzed copy (layer 2) go to the history palette and click on the "snapshot" icon at the bottom of the palette (see sample below). If you scroll up to the top of the history palette you will see two history "states" the first is the original file as you opened it, the second is the snapshot you just took.
Now, With layer 2 selected Select ALL and delete everything on that layer. Yes, delete it, and rename the layer "history" because this is where you are going to paint with the History brush.
Click on the "eyeball" of the second history state. Get the History Brush (it's below the regular brush in the tool box). Here you can go to your brushes palette and select a water color brush (or chalk or any other "effect" brush you want). Paint away on the History Layer in the layers palette.
While painting, I lowered the opacity of the Original Background layer to about 28% so that it would "fill in" areas that weren't painted. That layer just filled in some soft color since the transparency was so low.
Two tips about the "History" layer. I usually put a layer below filled with white so I can get a good feel for what I'm painting. I did this on the Mallorca Cafe image, but liked the effect of the low opacity #3 layer and deleted it. Also, You can paint on the history layer then select all and "jump" your painted history to a new layer, delete everything on the "history" layer and start painting with a different brush. I sometimes have 3 or 4 layers "jumped" to their own layer.
Hope this helps. And I hope it opens a whole new world of
PS "painting" for you.