Here is how to sketch a photo
Step 1: With the photo newly opened in Photoshop, press Ctr+j to duplicate the Background layer.
Step 2: Press Shift+Ctrl+U to desaturate the layer.
Step 3: Press Ctrl+J to duplicate the desaturated layer.
Step 4: Press Ctrl+I to invert the layer.
Step 5: Press Shift+Alt+D to change the blend mode to Color Dodge.
Step 6: 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.
or Filter > Blur > Gausan blur. change the Radius value, until you are happy with that.
