Browse Prior Art Database

Programmable Aperture for Document Scanner

IP.com Disclosure Number: IPCOM000045439D
Original Publication Date: 1983-Mar-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 3 page(s) / 50K

Publishing Venue

IBM

Related People

Fischer, RB: AUTHOR [+2]

Abstract

The system shown in Fig. 1 will combine point by point grey level image information for an area on a document into a single averaged grey level value for that area. The X by Y rectangular area is herein referred to as the X by Y aperture size. In Fig. 2, a linear scanner 10 is shown moving from left to right across a document 12. An example of a 2 x 4 aperture size is depicted in Fig. 2. Each of the picture elements (pels) on the document are picked up by an individual element in scanner 10. Each picture element is encoded into an 8-bit grey level. The system depicted in Fig. 1 can process these 8-bit pels for any X by Y pel aperture size, where X and Y are powers of 2, averaging the grey levels for that aperture.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 3

Programmable Aperture for Document Scanner

The system shown in Fig. 1 will combine point by point grey level image information for an area on a document into a single averaged grey level value for that area. The X by Y rectangular area is herein referred to as the X by Y aperture size. In Fig. 2, a linear scanner 10 is shown moving from left to right across a document 12. An example of a 2 x 4 aperture size is depicted in Fig. 2. Each of the picture elements (pels) on the document are picked up by an individual element in scanner 10. Each picture element is encoded into an 8-bit grey level. The system depicted in Fig. 1 can process these 8-bit pels for any X by Y pel aperture size, where X and Y are powers of 2, averaging the grey levels for that aperture.

In operation, the 8-bit grey level code for a pel is received as image data at data-in latch 14. Prior to the receipt of the image data, the programmable aperture size is received at aperture latch 16 as an X count and a Y count corresponding to the X, Y dimensions of the aperture. The X, Y counts are passed on to control logic 18 which contains an X counter and a Y counter to keep track of processed pels within an aperture.

As the image data for each pel is received from scanner 10 along the length of the scanner, it is summed with previous data in adder 20, buffered in latch 22 and stored in (random-access memory) RAM 24. RAM 24 has an addressable storage position for each vertical segment where the segments have a length of Y pels. In other words, if scanner 10 is a 128-pel scanner and the Y dimension of the aperture size is 4, then RAM 24 uses 32 storage positions. Thus, the addresses for the RAM are generated by the address control 26 in response to the programmable Y dimension of the aperture size.

If the pel image data is within a Y high segment, the value stored for that segment in the RAM 24 is fed back to adder 20 to be added to the next pel image data in that Y high segment. In the present example where Y equals 4, after 4 pels have been accum...