Dot matrix print detector

Claim 2

A dot matrix print detector for use in an optical character recognition system for detecting the presence of characters having interior portions and edges appearing on a document printed in a dot matrix format comprising: means for scanning the document and for generating pixel signals representing pixel values of portions of potential characters appearing on the document located in a predetermined area containing a plurality of pixels; means for filtering said pixel signals and for generating a filtered signal, said filtered signal representing edge pixels of potential characters located in said predetermined area; first means for determining the energy level of said filtered signals for said predetermined area on the document for generating a first energy summation signal; second means for determining the energy level of said pixel signals generated by said scanning means for said predetermined area and for generating a second energy summation signal; and means for comparing said first and said second energy summation signals and for generating an output signal indicating the presence of doth matrix print characters in said predetermined area on the document.

Claim 3

The detector of claim 1 wherein said comparing means includes means for calculating the ratio between said first energy summation signal and said second energy summation signal and for comparing said ratio to a stored reference value.

Claim 4

The detector of claim 1 wherein said comparing means includes means for calculating the difference between said first energy summation signal and said second energy summation signal and for comparing said difference to a stored reference value.

Claim 5

The detector of claim 1 wherein said filter means includes a high pass filter.

Claim 6

The detector of claim 1 wherein said means for comparing said first and said second energy summation signals generates an output signal indicating that no decision is made as to the presence or absence of a dot matrix print character in the predetermined area.

Claim 7

The detector of claim 1 and further including: means for enhancing said pixel signals generated by said scanning means.

Claim 8

A dot matrix print detector for use in an optical character recognition system for detecting the presence of characters having interior portions and edges appearing on a document printed in a dot matrix print format comprising: means for scanning the document and for generating pixel signals representing pixel values of portions of potential characters appearing on the document located in a predetermined area containing a plurality of pixels; first means for filtering said pixel signals and for generating a first filtered signal, said first filter signal representing edge pixels of potential characters located in said predetermined area; first means for determining the energy level of said first filtered signals for said predetermined area on the document and for generating a first energy summation signal; second means for filtering said pixel signals and for generating a second filtered signal, said second filtered signal representing pixels within the interior of potential characters located in said predetermined area; second means for determining the energy level of said second filtered signals for said predetermined area and for generating a second energy summation signal; and means for comparing said first and said second energy summation signals and for generating an output signal representing the presence of dot matrix print characters in said predetermined area on the document.

Claim 9

A dot matrix print detector for use in an optical character recognition system for detecting the presence of characters having interior portions and edges appearing on a document printed in a dot matrix print format comprising: means for scanning the document and for generating pixel signals representing pixel values of portions of potential characters appearing on the document located in a predetermined area containing a plurality of pixels; first means for filtering said pixel signals and for generating a first filtered signal, said first filter signal representing edge pixels of potential characters located in said predetermined area; first means for determining the energy level of said first filtered signals for said predetermined area on the document and for generating a first energy summation signal; second means for filtering said pixel signals and for generating a second filtered signal, said second filtered signal representing pixels within the interior of potential characters located in said predetermined area; second means for determining the energy level of said second filtered signals for said predetermined area and for generating a second energy summation signal; and means for comparing said first and said second energy summation signals and for generating an output signal representing the presence of dot matrix print characters in said predetermined area on the document.

Claim 10

The detector of claim 7 wherein said comparing means includes means for calculating the ratio between said first energy summation signal and said second energy summation signal and for comparing said ratio to a stored reference value.

Claim 11

The detector of claim 7 wherein said comparing means includes means for calculating the difference between said first energy summation signal and said second energy summation signal and for comparing said difference to a stored reference value.

Claim 12

The detector of claim 7 wherein said first filter means includes a high pass filter and said second filter means includes a low pass filter.

Claim 13

The detector of claim 7 wherein said means for comparing said first and said second energy summation signals generates an output signal indicating that no decision is made as to the presence or absence of a dot matrix print character in the predetermined area.

Claim 14

The detector of claim 7 and further including: means for enhancing said pixel signals generated by said scanning means.