This technique works best with photos of fairly good quality (not a lot of compression artifacts or moire patterns [lots of little dots from the screening process]), and without any really large dark areas (July 2, 1999: I have worked out a technique for dealing with photos with dark areas).
First, do Layers-Duplicate. With your new top layer active, do Colors-Negative Image, then Colors-Grey Scale.
Set the blend mode on the top layer to Dodge. Your image will now appear almost blank. This is normal.
Now, do Image-Blur-Gaussian Blur. Set the radius to about 4 and hit the Proof button. Now you will see the pencil sketch effect. Adjust the radius until you like it. Higher numbers will thicken the lines and emphasize the shadows. I used a radius of 3 on this image. [Note: You can use the Retouch tool set to Soften instead of Gaussian Blur. This will give you more control over the process.]
If you like what you see, you're done.
There are some optional extra steps which you can take to emphasize the lines in your "sketch."
First, activate your background layer and do Layers-Duplicate. Then on your new middle layer do Image-Edge-Enhance. Set the blend mode on the middle layer to Darken, and move the Opacity slider down until it looks good. I generally use 20 or 30. For this image I used 24. The effect is subtle, but it does make a difference.
You can see in the middle photo below what happens to dark-colored areas of a photo using this technique.
For photos with large dark areas, follow up the technique above by duplicating the background layer, setting the blend mode on the duplicated layer to "burn," and lowering the opacity until the image looks like you want it to. I used an opacity of 5 on the finished image below.
©1999 Scott A. Munro
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