Photo to Pencil Sketch

Lets cover a simple method in Pencil Sketch Technique:

The first step, of course, is to open an image. Keep in mind that, with some methods, large areas of dark color may not turn out the way we want. Experimentation is key in finding the correct method for your individual project.

The next step should be obvious as well - duplicate the original layer. We do this so that if something goes wrong we still have the original at the bottom of the layers stack, to which we can revert. That said, you can duplicate the background layer by dragging the background layer down to the Create New Layer icon and releasing it, or by holding CTRL (CMD on the Mac) and hitting the J key, or by selecting Layer > Duplicate from the main menu with the background selected in the layers palette. Use whichever method you prefer.

The next mandatory step is to change the new layer into a black-n-white image. There are a few different ways to do this, some simple and some rather lengthy. Of course, you can go to the Image > Adjustments > Desaturate. Or, go to Image > Adjustments > Hue & Saturation and slide the Saturation slider all the way to the left. While here, you can do some rudimentary contrast adjustments with the Lightness slider.

Another method is to switch to Lab Color Mode and copy the Lightness channel to the clipboard, then switch back to RGB Mode and paste it into your image. The method that gives you the most control over the outcome, however, involves Image > Adjustments > Channel Mixer. Click the Monochrome checkbox, at the bottom of the dialog, and use the sliders to adjust the contrast. Here is yet another area where personal preferences come into play. In other words, make it look good to you - there are no set rules to follow.

High Pass:

This is the method that, I believe, can give the best results. Here, you want to take the black-n-white layer and run the Filter > Other > High Pass filter on it. In the dialog, set the Radius to a low number (i.e. 1.5 - 2.0). If you don't see enough detail in the image, you can duplicate the layer and set the Blending Mode of the top layer to Overlay then adjust the Opacity of this layer, if necessary. If you do this, though, make sure to merge these two layers before moving to the next step.

The next step is to duplicate this layer and set the Blending Mode of the top layer to Color Dodge. Viola`! - only the shadows remain. Grey areas may, sometimes, look a little blotchy but some Levels adjustments or the good ol' Eraser Tool can help with that.