Using Fourier information for the detection of the lumen in endoscope images

An endoscope is a viewing instrument used for examining the inside surfaces of the human body for the purpose of diagnosis and minor surgical treatment. To date, only highly skilled specialists have been able to perform endoscopic investigations. We are proposing to rectify this situation by using computer vision to provide automatic guidance and advice during colonoscopy. In order to navigate an endoscope automatically through the colon, we need to process colon images to extract information, in particular, the position of the lumen (the point to which the endoscope should be directed) with respect to the centre of the image. To achieve this, we have devised and implemented a new Fourier Domain method. Since real time performance is required, we have devised simplified mathematical equations that effectively reduce a 2D FFT (Fast Fourier Transform) into two 1D FFTs. We found it was necessary to use a tapering window to minimize the edge discontinuity problem that leads to mis-classification. The results that we have obtained demonstrate that the method is highly effective in identifying the lumen position