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Method for Detecting Cursor

IP.com Disclosure Number: IPCOM000044587D
Original Publication Date: 1984-Dec-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Fujisawa, H: AUTHOR

Abstract

This article describes the precise detection of slidably mounted white cursors on a black background level, by counting the total black bits in each of the small areas of the cursor, summing the counts of three successive small areas, and comparing the summed counts with a threshold value. Such cursors are mounted on the side of a document glass platen of a document scanner to specify a partial area of the document to be scanned. The figure shows two cursors CL and CR, which are slidably mounted, in parallel with the scan direction, on the black background color. The cursors are white colored, and sometimes, black dust or other material deposits on the white cursors, resulting in a decrease of reliability of the cursor detection. The algorithm in this article solves this problem.

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Method for Detecting Cursor

This article describes the precise detection of slidably mounted white cursors on a black background level, by counting the total black bits in each of the small areas of the cursor, summing the counts of three successive small areas, and comparing the summed counts with a threshold value. Such cursors are mounted on the side of a document glass platen of a document scanner to specify a partial area of the document to be scanned. The figure shows two cursors CL and CR, which are slidably mounted, in parallel with the scan direction, on the black background color. The cursors are white colored, and sometimes, black dust or other material deposits on the white cursors, resulting in a decrease of reliability of the cursor detection. The algorithm in this article solves this problem. STEP 1 It is assumed that the cursors are sampled by 30 scan lines, and the area of 30 scan lines is divided into a plurality of small areas of 8 x 30 bits. Black bits in each 8 x 30-bit area are counted, and the counts of the successive small areas are stored in a table. Graph A shows the content of the table. If dust deposits on a second small area in the cursor CR, the count representing the dust appears on the graph A, as shown. STEP 2 The counts of the three successive small areas are summed and plotted, as shown in graph B. For example, the count values of the small areas "a", "b" and "c" are summed and plotted on a point "A", the count values of the sma...