General-Purpose Thresholding Algorithm for Mixed Format Documents
Original Publication Date: 1986-Oct-01
Included in the Prior Art Database: 2005-Mar-09
This article describes a family of general-purpose discriminating/ thresholding techniques for processing documents containing line copy information (LC), continuous tone information (CT) and halftone information (HT). The picture elements (PELs) of a scanned document are automatically classified as either line copy (LC) or nonline copy (NLC) and then thresholded accordingly. Devices for making this classification are referred to as "discriminators". Devices for thresholding the classified PELs are known as "thresholders". This article discusses a family of discriminators and thresholders that can be combined in various ways to cover the range of quality, function and cost. The menu for discriminators and thresholding techniques is given in Fig. 1. The following is an explanation of the terms used in Fig. 1.