Browse Prior Art Database

AREA MAPPING TABLE LOOK UP SCHEME

IP.com Disclosure Number: IPCOM000026706D
Original Publication Date: 1993-Apr-30
Included in the Prior Art Database: 2004-Apr-06
Document File: 6 page(s) / 224K

Publishing Venue

Xerox Disclosure Journal

Abstract

Proposed is the implementation of a look up table technique for a resolution conversion area mapping algorithm. The technique accounts for the table size and utilizes the symmetry found in the algorithm to optimize the table and reduce its size. The method is oriented toward producing an entire line as identified by an output window. All the input pixels that are necessary to produce the output scan line are identified. These pixels are then combined to form an address location in the look up table such that the addressed location contains the output values for that particular scan line. The look up table contains data for each output scan line where the size of the table is defined by a value 2X, where X is equal to the number of input pixels required to determine a corresponding output pixel. The number of the table look up entries is determined by 2N-1, where N represents the input window dimensions NxN. This design allows for an entire output tile to be created in just N steps, where N is again, by definition, the input window dimensions NXN.

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Page 1 of 6

XEROX DISCLOSURE JOURNAL

AREA MAPPING TABLE LOOK UP SCHEME U.S. C1.3551287 Robert E. Coward

Proposed Classification Int. C1. H04n 01/40

FIG. IA FIG. IB

XEROX DISCLOSURE JOURNAL - Vol. 18, No. 2 MarcWAprill993 217

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Page 2 of 6

AREA MAPPING TABLE LOOK UP SCHEME (Cont'd)

r--- r--- r------y I

FIG. 2A

FIG. 26

-

12345678

FIG. 2C

218 XEROX DISCLOSURE JOURNAL - Vol. 18, No. 2 MarchlApril 1993

[This page contains 1 picture or other non-text object]

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AREA MAPPING TABLE LOOK UP SCHEME (Cont'd)

I I I I I I I I I

-- -7-- - t -'-I----'

I I I

-,,-l,,-L,.,-! ----.

I I I I I I

I I +-+--- t--1---- I

I

I. I I I I I I I

FIG. 3A FIG. 36

I I I

FIG. 3C

FIG. 30

XEROX DISCLOSURE JOURNAL - Vol. 18, No. 2 MarcWAprill993 219

[This page contains 1 picture or other non-text object]

Page 4 of 6

AREA MAPPING TABLE LOOK UP SCHEME (Cont'd)

Proposed is the implementation of a look up table technique for a resolution conversion area mapping algorithm. The technique accounts for the table size and utilizes the symmetry found in the algorithm to optimize the table and reduce its size. The method is oriented toward producing an entire line as identified by an output window. All the input pixels that are necessary to produce the output scan line are identified. These pixels are then combined to form an address location in the look up table such that the addressed location contains the output values for that particular scan line. The look up table contains data for each output scan line where the size of the table is defined by a value 2X, where X is equal to the number of input pixels required to determine a corresponding output pixel. The number of the table look up entries is determined by 2N-1, where N represents the input window dimensions NxN. This design allows for an entire output tile to be created in just N steps, where N is again, by definition, the input window dimensions NXN.

Figures IA, lB, and 1C illustrate a simple example of the area mapping look up table plan. Figure 1A represents an output tile for a resolution X and Figure 1B represents an input tile for a resolution Y. In this example, the resolution Y, of the input tile, is less than the resolution X of the output tile.

When the two tiles are superimposed, as defined in the area mapping algorithm, a relationship between the input and output pixels is identified. The crosshatched area of the two superimposed tiles shown in Figure lC,

defines the first output scan line. As illustrated in Figure lC, the first output scan line falls entirely within the input scan line. This defines a table of 2X
entries, where X is the number of input pixels requires to describe the output pixels. In this example, for scan line number 1, X is equal to 4.

An example of an index calculation for output scan line 2 is illustrated in Figures 2A, 2B and 2C. The position of the output scan line 2 within the output window is shown in Figure 2A. Figures 2B shows t...