edge Linking dip.pptx

edge Linking dip.pptx

1. KUVEMPU UNIVERSITY JNANASAHYADRI SHANKARGATTA SEMINAR TOPIC ON EDGE LINKING UNDER THE GUIDANCE BY Dr. SURESHA M Associate Professor Dept.Of.MCA Kuvempu University Jnana sahyadri Shanakargatta Submitted by Shashikala v Reg no: PS202537 3 rd sem Mca Dept.Of.MCA Kuvempu university Jnana sahyadri Shankargatta M

2. Edge linking Used to group the edge points that are detected using edge detection algorithms. Set of pixels from edge detecting algorithms, seldom define a boundary completely because of noise, breaks in the boundary etc. Therefore, Edge detecting algorithms are typically followed by linking and other detection procedures, designed to assemble edge pixels into meaningful boundaries . 2 types of edge linking local processing global processing

3. Local processing One of the simplest approches for linking edge ponts is to an analyze the characteristics of pixels in a small neighbourhood (say 3x3, or 5x5 ) abou every point ( x,y ) in an image that has been labeled an edge point. All points that are similar according to set of predefined criteria are linked,forming an edge of pixels that those criteria. The two principal properties used for establishing similarity of edge pixels Strength of the response of the gradient operator used to produce the edge pixel The direction of the gradient vector.

4. Global processing using Hough Transform Hough transform is most commonly used for the detection of regular curves such as lines,circles,ellipses , etc The main advantage of the hough transform technique is that it is tolerant of gaps in feature boundary descriptions and is relatively unaffected by image noise. It maps a straight line y= mx+c in a Cartesian coordinate system into a single point in the ( ρ,θ ) plane or ρ= xcos θ+ysin θ For a point ( x,y ) in the Cartesian coordinate plane , there will be an infinite number of curves in the ( ρ,θ ) plane

5. Edge linking using H ough transform Compute the gradient of an image and threshold it to obtain a binary image . Specify subdivision in the p0(theta) plane. Examine the counts of the accumulator cells for high pixels concemtrations . Examine the relationship (for continuity)between pixels in a chosen cell.

6. Thank you ….