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Predictable Line Drawings  - or

Creating Line Drawings in Photoshop

category: digital photography and image editing

There are a variety of interesting and creative ways to convert an RGB image into a line drawing in Photoshop. One method stands out as being predictably successful, especially when you want a very finished looking drawing with lots of nice shading. As with most of these techniques, you'll want to start this one by converting your RGB image into black and white. The most straightforward way to convert your image to black and white is to click Image, Adjustments, and then Desaturate, but this is probably not your best choice. Better is to select a channel that has good detail and contrast in the areas of your image you would like to emphasize in your line drawing and use that channel. You can also enhance a channel with the channel mixer. If you use any method that leaves your image in greyscale mode, such as converting to Lab color and capturing the lightness channel, or, of course, if you start with a black and white image, be sure to convert your image to RGB mode before you go on.

One more caution before proceeding. Remember, line drawings are about edges, and edges are about contrast; if you don't get the results you want from any line drawing technique, you can always back up and increase the contrast of your image and/or sharpen your image with unsharp mask. Anyway, if you're starting with a decent image, this technique will usually give you good results without a lot of playing around on the front end, so try it first and see what you get.

Now, here goes. Your black and white subject image is on a layer, background is OK, and all other layers are nonvisible. Duplicate the subject layer so that your layers palette shows your black and white image as Layer 1 and Layer 1 Copy. Click on Layer 1 Copy to highlight it; click Image, Adjustments, and then Invert. Now Layer 1 Copy looks like a negative of Layer 1. With Layer 1 Copy still selected, click on the blend mode drop-down on the layers palette (blend mode should now read Normal), and select Color Dodge. When you select Color Dodge as your blend mode, if you've done everything right, your image window should be completely white.

The last step in this technique brings the line drawing out of the two blended layers. With Layer 1 Copy still selected, click Filter, Blur, and then Gaussian Blur. Make sure that preview is checked on the filter dialog box, and then run the radius slider back and forth until you like what you see.

He said on 02.15.05 @ 02:59 PM CST