A scheme for storing object ID manifests in openEXR images

Abstract

There are various approaches to storing numeric IDs as extra channels within CG rendered images. Using these channels, individual objects can be selected and separately modified. To associate an object with a text string a table or manifest is required mapping numeric IDs to text strings. This allows readable identification of ID-based selections, as well as the ability to make a selection using a text search. A scheme for storage of this ID Manifest is proposed which is independent of the approach used to store the IDs within the image. The total size of the raw strings within an ID Manifest may be very large but often contains much repeated information. A novel compression scheme is therefore employed which significantly reduces the size of the manifest.