To create the Sketch Effect image you have to follow some simple steps
- Open any image at Photoshop-CS, Create one duplcate layer by pressing CTRL + J or Select menu Layer -> Duplicate Layer
- After creating duplicate layer make it Desaturate by pressing SHIFT + CTRL + U or Select menu Image -> Adjustment -> Desaturate
- Duplicate this Desaturate Layer, make it Invert by pressing CTRL + I or Select menu Image -> Adjustment -> Invert
- After Inverting, make the blending Mode Liner Dodge by right click the layer Select the Blendings Option
Now you have got the final result of sketch...