Formulating Image Outline Programmatically (Preferrably C#/C++ coding, or pseudo coding)

Question

I would just like to ask for assistance to anyone on the logic, and much better sample code of formulating an image\'s outline.

To make it clearer, I\'m talking abo

Answer 1

One way is to use a general edge detection algorithm. For example, Sobel edge detection. However, it's not optimized for clean, antialiased, two-color images like the example below, so it produces a somewhat rough result. To better preserve the antialiasing, and get a smooth result, I suggest the following algorithm:

Image blurredImg = gaussianBlur(sourceImg, blurRadius = desiredOutlineWidth);
const float sharpnessCoef = 0.1; // value may need tuning or may need to
                                 // depend on the blur radius
Image dilatedImg = from blurredImg, map all pixels with
                   brightness > sharpnessCoef to white and
                   multiply the rest by 1 / sharpnessCoef
Image smoothResult = subtract sourceImg from dilatedImg

Example:

Answer 2

Consider using image processing techniques, like this one:

http://www.codeproject.com/KB/cs/Canny_Edge_Detection.aspx