Browse Prior Art Database

Algorithm for Detecting the Position of a Chipsite

IP.com Disclosure Number: IPCOM000121526D
Original Publication Date: 1991-Sep-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 2 page(s) / 56K

Publishing Venue

IBM

Related People

Saitoh, F: AUTHOR

Abstract

An algorithm is described which detects the position of a chipsite on a substrate by image processing. It can detect the position even if the image does not have good contrast.

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This is the abbreviated version, containing approximately 100% of the total text.

Algorithm for Detecting the Position of a Chipsite

      An algorithm is described which detects the position of a
chipsite on a substrate by image processing.  It can detect the
position even if the image does not have good contrast.

      Fig. 1 shows a gray scale image including a chipsite. The final
purpose of the algorithm is to detect the positions of four dark
stripe regions which extend between the solder pad array and EC
(engineering change) pad array to surround the chipsite.  Fig. 2
shows a part of Fig. 1 and includes a vertical dark stripe to be
detected.

      The algorithm is executed as follows.
(1) If gray scale values of all pixels on each of vertical pixel
lines of the image are added, then we will obtain a result such as
shown in graph A.  However, graph A does not provide an emphasized
feature. To solve this problem, in this scheme, only brighter pixel
values are added vertically.  N pixels of brighter gray scale values
are selected from each vertical pixel line and their values are
added.  The result is indicated by graph B.
(2) Then graph B is integrated using the width  of the dark stripe.
The operation is repeated on all positions of the X axis. The result
of the integration is shown in graph C.
(3) The position at which graph C becomes minimum is detected. The
detected position indicates the center of the dark stripe.

      The positions of the other three dark stripes are detected
using the same steps.