Multi-bit image edge enhancement method and apparatus

Claim 3

A method for enhancing the displayed image of a print or display apparatus as recited in claim 1 wherein the convolving of each said sample matrix with each said gradient mask is accomplished using boolean algebra.

Claim 4

A method for enhancing the displayed image of a print or display apparatus as recited in claim 2 wherein a is equal to 3 and b is equal to 3.

Claim 5

A method for enhancing the displayed image of a print or display apparatus as recited in claim 2 wherein during said convolution step all said gradient masks are simultaneously convolved with the sample matrix.

Claim 6

A method for enhancing the displayed image of a print or display apparatus as recited in claim 2 wherein during said comparison step a subset of said reference bit patterns is simultaneously compared to said sample matrix and its said previously and yet to be evaluated adjacent bits.

Claim 7

A method for enhancing the displayed image of a display apparatus as recited in claim 2 wherein said compensated signal pulse causes the dot normally representing the central bit to be replaced by one or more subdots having special characteristics different from the dot replaced.

Claim 8

A method for enhancing the displayed image of a print or display apparatus as recited in claim 1 wherein a is equal to 3 and b is equal to 3.

Claim 9

A method for enhancing the displayed image of a print or display apparatus as recited in claim 1 wherein during said convolution step all said gradient masks are simultaneously convolved with the sample matrix.

Claim 10

A method for enhancing the displayed image of a print or display apparatus as recited in claim 8 wherein during said comparison step a subset of said reference bit patterns is simultaneously compared to said sample matrix and its said previously and yet to be evaluated adjacent bits.

Claim 11

A method for enhancing the displayed image of a display apparatus as recited in claim 8 wherein said compensated signal pulse causes the dot normally representing the central bit to be replaced by one or more subdots having special characteristics different from the dot replaced.

Claim 12

A method for enhancing the displayed image of a print or display apparatus as recited in claim 1 wherein during said comparison step a subset of said reference bit patterns is simultaneously compared to said sample matrix and its said previously and yet to be evaluated adjacent bits.

Claim 13

A method for enhancing the displayed image of a display apparatus as recited in claim 11 wherein said compensated signal pulse causes the dot normally representing the central bit to be replaced by one or more subdots having special characteristics different from the dot replaced.

Claim 14

A method for enhancing the displayed image of a print or display apparatus as recited in claim 12 wherein said subdots change the apparent width and/or height of the dot replaced.

Claim 15

A method for enhancing the displayed image of a display apparatus as recited in claim 1 wherein said compensated signal pulse causes the dot normally representing the central bit to be replaced by one or more subdots having special characteristics different from the dot replaced.

Claim 16

A method for enhancing the displayed image of a print or display apparatus as recited in claim 14 wherein said subdots change the apparent width and/or height of the dot replaced.

Claim 19

A method for enhancing the displayed image of a print or display apparatus as recited in claim 16 wherein the convolving of each said sample matrix with each said gradient mask is accomplished using boolean algebra.

Claim 20

A method for enhancing the displayed image of a print or display apparatus as recited in claim 17 wherein a is equal to 3 and b is equal to 3.

Claim 21

A method for enhancing the displayed image of a print or display apparatus as recited in claim 17 wherein during said convolution step all said gradient masks are simultaneously convolved with the sample matrix.

Claim 22

A method for enhancing the displayed image of a print or display apparatus as recited in claim 17 wherein during said comparison step a subset of said reference bit patterns is simultaneously compared to said sample matrix and its said previously and yet to be evaluated adjacent bits.

Claim 23

A method for enhancing the displayed image of a display apparatus as recited in claim 17 wherein said compensated signal pulse causes the dot normally representing the central bit to be replaced by one or more subdots having special characteristics different from the dot replaced.

Claim 24

A method for enhancing the displayed image of a print or display apparatus as recited in claim 16 wherein a is equal to 3 and b is equal to 3.

Claim 25

A method for enhancing the displayed image of a print or display apparatus as recited in claim 16 wherein during said convolution step all said gradient masks are simultaneously convolved with the sample matrix.

Claim 26

A method for enhancing the displayed image of a print or display apparatus as recited in claim 23 wherein during said comparison step a subset of said reference bit patterns is simultaneously compared to said sample matrix and its said previously and yet to be evaluated adjacent bits.

Claim 27

A method for enhancing the displayed image of a display apparatus as recited in claim 23 wherein said compensated signal pulse causes the dot normally representing the central bit to be replaced by one or more subdots having special characteristics different from the dot replaced.

Claim 28

A method for enhancing the displayed image of a print or display apparatus as recited in claim 16 wherein during said comparison step a subset of said reference bit patterns is simultaneously compared to said sample matrix and its said previously and yet to be evaluated adjacent bits.

Claim 29

A method for enhancing the displayed image of a display apparatus as recited in claim 26 wherein said compensated signal pulse causes the dot normally representing the central bit to be replaced by one or more subdots having special characteristics different from the dot replaced.

Claim 30

A method for enhancing the displayed image of a print or display apparatus as recited in claim 27 wherein said subdots change the apparent width and/or height of the dot replaced.

Claim 31

A method for enhancing the displayed image of a display apparatus as recited in claim 16 wherein said compensated signal pulse causes the dot normally representing the central bit to be replaced by one or more subdots having special characteristics different from the dot replaced.

Claim 32

A method for enhancing the displayed image of a print or display apparatus as recited in claim 29 wherein said subdots change the apparent width and/or height of the dot replaced.

Claim 33

Apparatus for enhancing the output of a print or display device which produces an image in dot matrix format, comprising: means for generating a set of gradient masks each of which represents a plurality of edge segment transition conditions and includes a matrix of "a×b" cells each cell of which is assigned a numerical weight corresponding to the relative lightness or darkness of the corresponding pixel of an image having an edge segment passing through a center pixel of the matrix; means for generating a data signal including a plurality of multi-bit data terms representative on a pixel by pixel basis of a bit map image to be printed or displayed; means for evaluating each said multi-bit data term, and if the value thereof is equal to or greater than a predetermined threshold value, then generating a data bit of a first state, if the value is less than said threshold value, then generating a data bit of a second state; storage means for temporarily storing a predetermined number of consecutive bits in a predetermined number of consecutive lines of said bit map image; means for selecting subsets of said bits forming a sample matrix of "a×b" bits, the central bit of each sample matrix being a candidate for modification; means for convolving each said sample matrix with each said gradient mask to detect those sample matrix having an edge segment passing through their central bit, said edge segment being defined as a series of adjacent aligned data bits of the same data state forming a straight line having a single slope, and to determine the direction of a gradient change; means for generating a set of reference bit patterns each of which includes a sub-pattern of bits corresponding to one possible combination of bits of the same data state aligned in one or more edge segments, said pattern including an "a×b" matrix of bits, a first predetermined number of bits disposed adjacent one side of said matrix, and a second predetermined number of bits disposed adjacent another side of said matrix; means for comparing each said sample matrix having an edge segment passing through its central bit, a predetermined number of adjacent previously evaluated bits, and a predetermined number of adjacent yet to be evaluated bits to each pattern of at least a sub-set of said set of reference bit patterns; means for generating, for each match found to a reference pattern including a predetermined type of segment transition, a modification signal for modifying the central bit of said sample matrix dependent upon the type of transition detected; means for combining each said modification signal with its corresponding multi-bit data term to generate a compensated value signal; means responsive to said compensated value signal and operative to generate a compensated signal pulse which during at least a portion of its period is of a first data state, or is of a second data state for the duraction of its period; means for converting each said multi-bit data term into a corresponding percent gray signal; and means for determining whether or not each said compensated signal pulse is of said first data state and for transmitting each said compensated signal pulse of said first state to a print or display apparatus to develop a corresponding output, but if said compensated signal pulse is of said second state, then causing the corresponding percent gray signal to be transmitted to the print or display apparatus to develop a corresponding output.

Claim 34

Apparatus for enhancing the output of a print or display device which produces an image in dot matrix format, comprising: means for generating a set of gradient masks each of which represents a plurality of edge segment transition conditions and includes a matrix of "a×b" cells each cell of which is assigned a numerical weight corresponding to the relative lightness or darkness of the corresponding pixel of an image having an edge segment passing through a center pixel of the matrix; means for generating a data signal including a plurality of multi-bit data terms representative on a pixel by pixel basis of a bit map image to be printed or displayed; means for evaluating each said multi-bit data term, and if the value thereof is equal to or greater than a predetermined threshold value, then generating a data bit of a first state, if the value is less than said threshold value, then generating a data bit of a second state; storage means for temporarily storing a predetermined number of consecutive bits in a predetermined number of consecutive lines of said bit map image; means for selecting subsets of said bits forming a sample matrix of "a×b" bits, the central bit of each sample matrix being a candidate for modification; means for convolving each said sample matrix with each said gradient mask to detect those sample matrix having an edge segment passing through their central bit, said edge segment being defined as a series of adjacent aligned data bits of the same data state forming a straight line having a single slope, and to determine the direction of a gradient change; means for generating a set of reference bit patterns each of which includes a sub-pattern of bits corresponding to one possible combination of bits of the same data state aligned in one or more edge segments, said pattern including an "a×b" matrix of bits, a first predetermined number of bits disposed adjacent one side of said matrix, and a second predetermined number of bits disposed adjacent another side of said matrix; means for comparing each said sample matrix having an edge segment passing through its central bit, a predetermined number of adjacent previously evaluated bits, and a predetermined number of adjacent yet to be evaluated bits to each pattern of at least a sub-set of said set of reference bit patterns; means for generating, for each match found to a reference pattern including a predetermined type of segment transition, a modification signal for modifying the central bit of said sample matrix dependent upon the type of transition detected; means for combining each said modification signal with its corresponding multi-bit data term to generate a compensated value signal; means responsive to said compensated value signal and operative to generate a compensated signal pulse which during at least a portion of its period is of a first data state, or is of a second data state for the duraction of its period; means for converting each said multi-bit data term into a corresponding percent gray signal; and means for determining whether or not each said compensated signal pulse is of said first data state and for transmitting each said compensated signal pulse of said first state to a print or display apparatus to develop a corresponding output, but if said compensated signal pulse is of said second state, then causing the corresponding percent gray signal to be transmitted to the print or display apparatus to develop a corresponding output.

Claim 35

Apparatus for enhancing the output of a print or display apparatus as recited in claim 31 wherein said means for convolving includes: edge detector means for detecting the existence of an edge segment in a sample matrix, and segment change detection means for detecting a segment change within the sample matrix.

Claim 36

Apparatus for enhancing the output of a print or display apparatus as recited in claim 32 wherein said segment change detector includes vertical segment change detecting means and horizontal segment change detecting means.

Claim 37

Apparatus for enhancing the output of a print or display apparatus as recited in claim 31 wherein said means responsive to includes modulation logic means for modulating the display drive signal of said print or display device.

Claim 38

Apparatus for enhancing the output of a print or display apparatus as recited in claim 34 wherein said modulation logic means includes a plurality of programmable modulation registers for containing predetermined addressable modulation control signals.

Claim 39

Apparatus for enhancing the output of a print or display apparatus as recited in claim 35 wherein said apparatus is embodied in an application specific integrated circuit device which can be added to a conventional display device.

Claim 40

Apparatus for enhancing the output of a print or display apparatus as recited in claim 35 wherein said modulation logic means is adapted to support an external ROM/PAL containing additional predetermined addressable modulation control signals.

Claim 41

Apparatus for enhancing the output of a print or display device which produces an image in dot matrix format, comprising: means for generating a set of gradient masks each of which represents a plurality of edge segment transition conditions and includes a matrix of "a×b" cells each cell of which is assigned a numerical weight corresponding to the relative lightness or darkness of the corresponding pixel of an image having an edge segment passing through a center pixel of the matrix; means for generating a data signal including a plurality of multi-bit data terms representative on a pixel by pixel basis of a bit map image to be printed or displayed; means for evaluating each said multi-bit data term, and if the value thereof is equal to or greater than a predetermined threshold value, then generating a data bit of a first state, if the value is less than said threshold value, then generating a data bit of a second state; storage means for temporarily storing a predetermined number of consecutive bits in a predetermined number of consecutive lines of said bit map image; means for selecting subsets of said bits forming a sample matrix of "a×b" bits, the central bit of each sample matrix being a candidate for modification; means for convolving each said sample matrix with each said gradient mask to detect those sample matrix having an edge segment passing through their central bit, said edge segment being defined as a series of adjacent aligned data bits of the same data state forming a straight line having a single slope, and to determine the direction of a gradient change; means for generating a set of reference bit patterns each of which includes a sub-pattern of bits corresponding to one possible combination of bits of the same data state aligned in one or more edge segments, said pattern including an "a×b" matrix of bits, a first predetermined number of bits disposed adjacent one side of said matrix, and a second predetermined number of bits disposed adjacent another side of said matrix; means for comparing each said sample matrix having an edge segment passing through its central bit, a predetermined number of adjacent previously evaluated bits, and a predetermined number of adjacent yet to be evaluated bits to each pattern of at least a sub-set of said set of reference bit patterns; means for generating, for each match found to a reference pattern including a predetermined type of segment transition, a modification signal for modifying the central bit of said sample matrix dependent upon the type of transition detected; means for combining each said modification signal with its corresponding multi-bit data term to generate a compensated value signal; means for combining each said modification signal with its corresponding multi-bit data term to generate a compensated value signal; means responsive to each said compensated signal pulse and operative to cause a gray scale print or display apparatus to develop a corresponding output, but in the absence of a compensated value signal, responsive to the multi-bit data term and operative to cause the gray scale print or display apparatus to develop a corresponding output.

Claim 42

Apparatus for enhancing the output of a print or display device which produces an image in dot matrix format, comprising: means for generating a set of gradient masks each of which represents a plurality of edge segment transition conditions and includes a matrix of "a×b" cells each cell of which is assigned a numerical weight corresponding to the relative lightness or darkness of the corresponding pixel of an image having an edge segment passing through a center pixel of the matrix; means for generating a data signal including a plurality of multi-bit data terms representative on a pixel by pixel basis of a bit map image to be printed or displayed; means for evaluating each said multi-bit data term, and if the value thereof is equal to or greater than a predetermined threshold value, then generating a data bit of a first state, if the value is less than said threshold value, then generating a data bit of a second state; storage means for temporarily storing a predetermined number of consecutive bits in a predetermined number of consecutive lines of said bit map image; means for selecting subsets of said bits forming a sample matrix of "a×b" bits, the central bit of each sample matrix being a candidate for modification; means for convolving each said sample matrix with each said gradient mask to detect those sample matrix having an edge segment passing through their central bit, said edge segment being defined as a series of adjacent aligned data bits of the same data state forming a straight line having a single slope, and to determine the direction of a gradient change; means for generating a set of reference bit patterns each of which includes a sub-pattern of bits corresponding to one possible combination of bits of the same data state aligned in one or more edge segments, said pattern including an "a×b" matrix of bits, a first predetermined number of bits disposed adjacent one side of said matrix, and a second predetermined number of bits disposed adjacent another side of said matrix; means for comparing each said sample matrix having an edge segment passing through its central bit, a predetermined number of adjacent previously evaluated bits, and a predetermined number of adjacent yet to be evaluated bits to each pattern of at least a sub-set of said set of reference bit patterns; means for generating, for each match found to a reference pattern including a predetermined type of segment transition, a modification signal for modifying the central bit of said sample matrix dependent upon the type of transition detected; means for combining each said modification signal with its corresponding multi-bit data term to generate a compensated value signal; means for combining each said modification signal with its corresponding multi-bit data term to generate a compensated value signal; means responsive to each said compensated signal pulse and operative to cause a gray scale print or display apparatus to develop a corresponding output, but in the absence of a compensated value signal, responsive to the multi-bit data term and operative to cause the gray scale print or display apparatus to develop a corresponding output.