Software systems for Computer Vision and Image Processing

Sungsoo Ha

Prof. Murali Subbarao (Stony Brook University)Prof. A.N. Rajagopalan (Indian Institute of Technology, Madras, India)

Arnav V. Bhavsar (PhD student, Indian Institute of Technology, Madras, India)

Contents

• Machine (or Computer) Vision System• Image Processing• Early Vision Process– Edge detection (the Canny Edge detection)

• Intermediate Vision Process– Hough Transform

• High Vision Process– Computed Tomography (Filtered backprojection algorithm)

Machine Vision System

• Image Processing• Early Vision Process• Intermediate Vision Process• High Vision Process

Image ProcessingEnhancing Image Contrast Reducing Noise Smoothing

Edge detection Arbitrary Filter Linear filter: Convolution

The Canny Edge Detector

• Edge in an image– Significant local changes in an image– Important features for analyzing image

• Canny Edge Detector– The optimal edge detector– Low error rate– Well localized edge points– Only one response to a single edge

Cont’d (Canny Edge detector)

• Algorithm 1. Filtering: Smooth the image2. Enhancement: Compute the gradient magnitude and orientation3. Detection: Apply non-maxima suppression4. Localization: Use double thresholding

Hough Transform (HT) for line detection

• What is difference with edge detector?• Application: geometric pattern matching

1. An image of a single object2. Decomposed into lines, curves, or other shapes3. Matched with those in the desired object

Computed Tomography (CT)

CT : the cross-sectional imaging of an object from its projection data

Parallel beam projection

Filtered back-projection algorithm

3D Volume Rendering &Graphic User Interface (GUI)

• System & Software Requirement– OpenGL extension version (2.0)– Cg toolkit (the latest version)– GeForce 8000 series (at least)

Conclusion

• Summarize– Realize very basic and simple applications– Help to understand overall of machine vision system

• Future work– Improving Hough Transform to detect arbitrary

curves– Medical Image Processing

• Two-level volume rendering• SPECT and PET statistical image reconstruction