Investigating Occlusion and Discretization Problems in Image Space Blurring Techniques Brian A. Barsky a,b , Michael J. Tobias a , Daniel R. Horn a , Derrick P. Chu a,c a Computer Science Division, University of California, Berkeley, California, 94720-1776, USA b School of Optometry, University of California, Berkeley, California, 94720-2020, USA c Computer Science Department, University of California, Los Angeles, California, 90095-1596, USA Abstract Traditional computer graphics methods render images that appear sharp at all depths. Adding blur can add realism to a scene, provide a sense of scale, and draw a viewer’s attention to a particular region of a scene. Our image based blur algorithm needs to distinguish whether a portion of an image is either from a single object or is part of more than one object. This motivates two approaches to identify objects after an image has been rendered. We illustrate how these techniques can be used in conjunction with our image space method to add blur to a scene. Key words: Image forming and processing, Visual perception PACS: 42.30.Va, 42.66.Si 1 Introduction Images rendered with traditional computer graphics techniques appear com- pletely in focus. However, images formed by optical systems have depth of field; that is, some regions of the image are in focus while other are blurred. This is useful to draw a viewer’s attention to a specific region of the image and can help to indicate the scale of a particular scene. The rendering of a 3D Email address: barksy@cs.berkeley.edu (Brian A. Barsky). URL: http://www.cs.berkeley.edu/optical (Brian A. Barsky). Preprint submitted to Elsevier Science 23 September 2003