First choose your image - here is mine
|Lola, aged 2|
Now, duplicate your back ground image - press CTRL + J
Press Shift+Ctrl+U to desaturate the layer
Now your picture will be black and white - pretty eh?
Now press CTRL + J again to duplicate the desaturated layeryou should now have 3 layers...
Press Ctrl+I to invert the layer
Press Shift+Alt+D to change the blend mode to Colour Dodge
your picture will look like it's gone, but don't fret -
Go to Filter > Other > Minimum. Leave the Radius value set to 1 pixel and click OK to close out of the filter's dialog box
this merges the layers onto a new layer above the others
Press Shift+Alt+M to change the blend mode of the merged layer to Multiply, which darkens the sketch effect.
Lower the layer Opacity value if the sketch now appears too dark.
|see where highlighted|
Click on the Background layer in the Layers panel to select it, then press Ctrl+J to duplicate it.
Press Shift+Ctrl+] to jump the Background copy layer to the top of the layer stack.
Press Shift+Alt+C to change the blend mode to Colour to colour the sketch
Lower the Opacity value to reduce the intensity of the color if needed.
there... all done