只讲1.2.1大脑和 3. a simple edge detector ⇒ DoG即可

1 Introduction

1.1 Foreground or Background? Same edges

1.2 Edges are important

(A)Cave painting at Chauvet, France, about 30,000 B.C.; (B)Aerial photograph of the picture of a monkey as part of the Nazca Lines geoglyphs, Peru, about 700 – 200 B.C.; (C)Shen Zhou (1427-1509 A.D.): Poet on a mountain top, ink on paper, China; (D)Line drawing by 7-year old I. Lleras (2010 A.D.).

1.2.1大脑是如何从原始感知中“构建视觉特征表示”的？

We know edges are special from human (mammalian) vision studies.

对于场景分类而言，线图和照片差不多。 Walther, Chai, Caddigan, Beck & Fei-Fei, PNAS, 2011

1.3 Why do we care about edges?

• Extract information, recognize objects
• Recover geometry and viewpoint
• Edit images directly

1.4 Edge detection

1. Goal:  Identify sudden changes (discontinuities) in an image
   1. Intuitively, most semantic and shape information from the image can be encoded in the edges
   2. More compact than pixels