How can a photo be converted to a line drawing?

Photos can be converted to line drawings by manipulating them using filters available in image editing software. Two popular applications that can be used to achieve this effect are Adobe Photoshop and Gimp, an open source alternative.

There are certain steps that should be followed when using either program.

Adobe Photoshop
There are several different methods available to convert an image to a line drawing in Adobe Photoshop. This method uses the "High Pass" filter to achieve the desired effect:

• The image is opened in Photoshop and a duplicate of the background created.
• The "High Pass" filter is then applied by selecting it from the "Filter" menu. The radius chosen affects the final image.
• The "Note Paper" filter is applied by selecting it from the "Filter" menu.
• The resulting lines are converted from gray to black by making adjustments to the threshold correction, found under the "Adjustments" sub-menu of the "Image" menu.

Gimp
This method also uses high pass filtering, but in a slightly different way. The same steps can be achieved in Adobe Photoshop by using the corresponding tools.

• The image is first opened in Gimp and duplicated.
• A Gaussian blur is applied to the top layer.
• The top layer is inverted and its opacity reduced to 50 percent. The "Invert" tool is found under the "Colors" sub-menu of the "Image" menu.
• The two layers are merged by right-clicking on the top layer and selecting the "Merge Down" option.
• Contrast adjustments are made using the "Levels" tool.
• The resulting image is desaturated. Settings are adjusted to make the background white.