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If you look closely (scan it on a computer and zoon in) at a carbon pencil line you can see that there are differing shades of gray. I tried looking on the Internet for any kind of algorithm or statistical model for how that gray would be drawn programatically. Does anyone have information on this? Thanks a lot!! I want to make drawings on a computer that look they were drawn with a pencil. |
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Depending what tool you're using to draw the line to the screen will change the solution to this question, but the simplest method would be to have the intensity of line color be a function of its distance to the center of the line. Therefore you would have a black line that greys out at the edges. The other form that you could be talking about was the fact that paper is not perfectly smooth, thus the pencil will be darker on the hills and lighter on the valleys (on a minute scale of course). To do this you could just apply a couple of layers of noise in different shades of grey over your black pencil lines. The are further methods that come to mind, but they all depend on how you're actually planning on drawing to screen. For further research you can look into how digital artists fake pencil effects and see if any of those methods translate well into a programmable method. |
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It sounds like you're looking to implement something similar to anti-aliasing on whatever lines you're drawing. The high overview of anti-aliasing is it aims to reduce the jagged edges we perceive on pixelated lines by shading the pixels surrounding the line, so that the line fades into the background color. The result will look very much like the pencil effect you're describing. This article gives a very good explanation and sample implementation of anti-aliasing. Hope this helps :) |
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