A new algorithm for reconstruction of a 3D virtual colon segment from an individual image captured from colonoscopy is presented. Colonoscopy is currently the gold standard method for detection and prevention of colorectal cancer. However, the protective effect depends on the amount of colon mucosa that is actually seen by the endoscopist. The proposed algorithm takes contours of colon folds in the image as input and calculates the depth and the slant angle of each fold. Finally, the colon mucosa is created using Cubic Bezier Curve interpolation between the folds. The proposed algorithm is an important step toward 3D reconstruction of the virtual colon from video of an entire colonoscopy procedure. The reconstruction is potentially useful to estimate percent of colon mucosa inspected by the endoscopist.