• Edge-based primitives serve as foundational cues for image analysis and scene understanding, focusing on robust edge/curve extraction and line detection via local operators and Hough-type transforms.

• Geometric representations use shape descriptors, skeletonization, and contour-based descriptors to capture structure across views, enabling form description beyond pixel intensities.

• Texture-based and statistical descriptors enable early image classification and texture discrimination, bridging low-level features with scene understanding.

• Pattern recognition emerges as a unifying paradigm linking perception, cognitive processes and image analysis, with works on visual pattern discrimination, handwriting recognition, and depth perception.

• Segmentation and contour-based region delineation drive later processing, including tree-traversal segmentation and contour coding for image transmission and region matching.