Here’s a quick and easy way to get a quasi-sketch effect. This technique (and variations of it) is good for any photo that has distracting elements that you’d like to minimize, or a particular area you’d like to enhance. Open your photograph in Photoshop and duplicate the photo layer. Now select foreground and background colors that complement your photo, or just choose a foreground color and leave the background color white. With the top photo layer selected, go to FILTER>FILTER GALLERY>SKETCH>GRAPHIC PEN and mess around with the settings until it looks good, then click ok.
Now for the fun part – with the top layer (which has the graphic pen effect applied) still selected, click on the ADD LAYER MASK icon at the bottom of the layers palette. Your colors will change to a black foreground and white background. Select the gradient tool from the tool palette, make sure that either black to white or black to transparent is selected and chose either linear or radial blend modes and set the opacity to whatever you want. Now you simply click and drag on the photo and any black pixels temporarily erase the top layer allowing the bottom layer to show through. Don’t like it? Fill the mask with white and start over. You can also adjust the layer opacity and blending mode to get exactly the effect you want.
Tip: If you accidentally click off the mask layer or need to come back to it, you can make it active again by clicking on the mask icon next to your layer icon in the layers palette. Alternatively, open the channels palette by going to WINDOW>CHANNELS – it will display your RGB or CMYK channels and the transparency mask. Click on the mask channel to make it active.
More than sketching…
As you can imagine, there are multiple different effects that you can achieve using these same basic steps – instead of using the Graphic Pen filter, try a different one. Instead of using the gradient tool, use a brush to draw on the mask channel. Change the blending mode of the masked layer. Try with different colors. Below is a photo of a squirrel eating our leftover Halloween pumpkin that I quickly did a few samples of using brown and orange with just a little bit of the squirrel masked out.