EP0336776A2 — Image magnification

Claim 1

Independent Claim 194 words

A process for determining values of new pixels which are to be interpolated in a unit area which is surrounded by original pixel centers, when magnifying an image consisting of original pixels, comprising: a first step for detecting an angle of an original line image in a predetermined vicinity of said unit area by comparing values of a combination of original pixels in said predetermined vicinity of said unit area with each of a plurality of predetermined patterns of an arrangement of pixel values; a second step for selecting one of a plurality of predetermined modes of division of said unit area so that an angle of a dividing line which divides said unit area in the selected mode of division conforms to said angle detected in said first step; and a third step for determining a value of each of said new pixels by assigning a value which is determined based on the values of said original pixels in said vicinity, to all of the new pixels the centers of which are in each section of said unit area which section is generated by said mode of division selected in said second step.

Claim 2

Dependent Claim 194 words

A process for determining values of new pixels which are to be interpolated in a unit area which is surrounded by original pixel centers, when magnifying an image consisting of original pixels, comprising: a first step for detecting an angle of an original line image in a predetermined vicinity of said unit area by comparing values of a combination of original pixels in said predetermined vicinity of said unit area with each of a plurality of predetermined patterns of an arrangement of pixel values; a second step for selecting one of a plurality of predetermined modes of division of said unit area so that an angle of a dividing line which divides said unit area in the selected mode of division conforms to said angle detected in said first step; and a third step for determining a value of each of said new pixels by assigning a value which is determined based on the values of said original pixels in said vicinity, to all of the new pixels the centers of which are in each section of said unit area which section is generated by said mode of division selected in said second step.

Claim 3

Dependent Claim 28 words

A process according to claim 1, wherein said predetermined patterns includes patterns to detect a plurality of different portions of line images in a plurality of predetermined angles.

Claim 4

Dependent Claim 45 words

A process according to claim 1, wherein said unit area is a rectangle at each corner of which an original pixel center exists, and said predetermined vicinity includes 4×4 original pixels arranged in a 4×4 square lattice form having said unit area in its center.

Claim 5

Dependent Claim 20 words

A process according to claim 3, wherein said plurality of angles includes 0 degrees, 90 degrees, ±tan⁻¹1, ±ϑ, and ±(π/2-ϑ).

Claim 6

Dependent Claim 252 words

A process according to claim 4, wherein said modes of division include: a first mode wherein lines which divide said unit area includes the lines determined by x=0, y=0, x±y=1, and x±y=-1/2; a second mode wherein lines which divide said unit area includes the lines determined by x=0, y=0, y=±(tanϑ)(x-1/2), and y=±(tanϑ)(x+1/2); a third mode wherein lines which divide said unit area includes the lines determined by x=0, y=0, y-1/2=±(tanϑ)x, and y+1/2=±(tanϑ)x; and a fourth mode wherein lines which divide said unit area includes the lines determined by x=0, y=0, and y+1-(1/2)tanϑ=+(tanϑ)x≦0; a fifth mode wherein lines which divide said unit area includes the lines determined by x=0, y=0, and y-1+(1/2)tanϑ=-(tanϑ)x≧0; a sixth mode wherein lines which divide said unit area includes the lines determined by x=0, y=0, and y-1+(1/2)tanϑ=+(tanϑ)x≧0; a seventh mode wherein lines which divide said unit area includes the lines determined by x=0, y=0, and y+1-(1/2)tanϑ=-(tanϑ)x≦0; a eighth mode wherein lines which divide said unit area includes the lines determined by x=0, y=0, and x-(1/2)cotϑ+1=+(cotϑ)y≦0; a ninth mode wherein lines which divide said unit area includes the lines determined by x=0, y=0, and x-(1/2)cotϑ+1=-(cotϑ)y≦0; a tenth mode wherein lines which divide said unit area includes the lines determined by x=0, y=0, and x+(1/2)cotϑ-1=+(cotϑ)y≧0; and a eleventh mode wherein lines which divide said unit area includes the lines determined by x= 0, y= 0, and x+(1/2)cotϑ-1=-(cotϑ)y≧0; where x=0 corresponds to the vertical line, y=0 corresponds to the horizontal line, and x=±1/2 and y=±1/2 determine the boundary of said unit area.

Claim 7

Dependent Claim 152 words

A process according to claim 5, wherein values of said new pixels in each of a section (G9) the boundaries of which include both x =0 and y+1-(1/2)tanϑ=+(tanϑ)x≦0, a section (G10) the boundaries of which include both x =0 and y-1 +(1/2)tanϑ=-(tanϑ)x≧0, a section (G11) the boundaries of which include both x =0 and y-1+(1/2)tanϑ=+(tanϑ)x≧0, a section (G12) the boundaries of which include both x =0 and y+1-(1/2)tanϑ=-(tanϑ)x≦0, a section (G9′ )the boundaries of which include both y=0, and x-(1/2)cotϑ+1=+(cotϑ)y≦0, a section (G10′ ) the boundaries of which include both y=0, and x-(1/2)cotϑ+1 =-(cotϑ)y≦0, a section (G11′ ) the boundaries of which include both y =0, and x+(1/2)cotϑ-1=+(cotϑ)y≧0, and a section (G12′ ) the boundaries of which include both y =0, and x+(1/2)cotϑ-1=-(cotϑ)y≧0, are each an inverse of the value of the pixel the center of which is at a corner of said unit area which is the nearest to each section.

Claim 8

Dependent Claim 167 words

A process according to claim 6, wherein a value of said new pixels in each of sections the boundaries of which include both x=0 and y=0, in said first to third modes of division, is equal to A*(B+C+D+ F * K )+B*C*D*( F + K ), wherein A is a value of the pixel the center of which is at the corner which is the nearest to each section, B, C, and D are the values of the pixels corresponding to the other three pixels the center of which are at the other three corners of said unit area, and F and K are each the value of one of said original pixels included in said predetermined vicinity and, the centers of the original pixels F and K are ends of a hypotenuse of a right-angled equilateral triangle wherein the right angle of said triangle is formed by the centers of said pixels B, C, and D, and said hypotenuse includes said pixel center in the middle.

Claim 9

Dependent Claim 23 words

A process according to claim 3, wherein said plurality of angles includes 0 degrees, 90 degrees, ±tan⁻¹ 1, ±tan⁻¹ 1/2, and ±tan⁻¹ 2.

Claim 10

Dependent Claim 249 words

A process according to claim 8, wherein said modes of division include: a first mode wherein lines which divide said unit area includes the lines determined by x=0, y=0, x±y=1/2, and x±y=-1/2; a second mode wherein lines which divide said unit area includes the lines determined by x=0, y=0, x±y/2=1/2, and x±y/2=-1/2; a third mode wherein lines which divide said unit area includes the lines determined by x=0, y=0, x/2±y=1/2, and x/2±y=-1/2; a fourth mode wherein lines which divide said unit area includes the lines determined by x=0, y=0, and y=+2x≦0; a fifth mode wherein lines which divide said unit area includes the lines determined by x=0, y=0, and y=-2x≧0; a sixth mode wherein lines which divide said unit area includes the lines determined by x=0, y=0, and y=+2x≧0; a seventh mode wherein lines which divide said unit area includes the lines determined by x=0, y=0, and y=-2x≦0; a eighth mode wherein lines which divide said unit area includes the lines determined by x=0, y=0, and x=+2y≦0; a ninth mode wherein lines which divide said unit area includes the lines determined by x=0, y=0, and x=-2y≦0; a tenth mode wherein lines which divide said unit area includes the lines determined by x=0, y=0, and x=+2y≧0; and a eleventh mode wherein lines which divide said unit area includes the lines determined by x=0, y=0, and x=-2y≧0; where x=0 corresponds to the vertical line, y=0 corresponds to the horizontal line, and x=+1/2 and y=+1/2 determine the boundary of said unit area.

Claim 11

Dependent Claim 112 words

A process according to claim 1, further comprising, preceding to said first step, a step for dividing said unit area into sub-areas corresponding to each of said original pixel centers which is surrounding said unit area so that all points in each sub-area are nearer to the corresponding original pixel center than to other of said original pixel centers; and a step for determining one of said sub-areas in which a center of each of said new pixels exists; wherein said patterns, said combination of the original pixels used for said comparison, are defined for each of said sub-areas, and said predetrmined modes of division are defined within each of said sub-areas.

Claim 12

Dependent Claim 51 words

A process according to claim 10, wherein said unit area is a rectangle at each corner of which an original pixel center exists, and said predetermined vicinity for each of said original pixel centers respectively includes 3×3 original pixels arranged in a square lattice form having said corner in its center.

Claim 13

Dependent Claim 31 words

A process according to claim 1, wherein said predetermined patterns includes patterns each of which can detect a portion of a line image wherein the angle of the line image changes.

Claim 14

Dependent Claim 76 words

A process according to claim 12, wherein said predetermined vicinity includes eight further original pixels which are outside of said 4×4 square lattice, two of said eight further original pixels are abutting on each of the four original pixels which are at the corners of said 4×4 square lattice, and each of said two further original pixels each abutting in the vertical direction and in the horizontal direction of said each of the four original pixels.

Claim 15

Independent Claim 277 words

An apparatus for determining values of new pixels which are to be interpolated in a unit area which is surrounded by original pixel centers, when magnifying an image consisting of original pixels, comprising: a new pixel coordinate generating means (1) for generating a coordinate of a center of a new pixel for interpolating between the original pixel centers, according to a magnification rate; a pattern detecting means (4) for detecting one of a plurality of predetermined line images by comparing values of a combination of original pixels in a predetermined vicinity of said unit area with each of predetermined patterns; a selector means (507) for selecting one of a plurality of predetermined modes of division of said unit area according to said one of line images detected in said pattern detecting means (4), wherein said plurality of predetermined modes of division are provided, in advance, corresponding to said predetermined patterns; a section determining means (510, 61, 62) for determining in which section the center of said new pixel is, in accordance with information of lines dividing said unit area in said mode of division which is selected in said selector means (507), wherein said section is one of a plurality of sections which is generated by each of said modes of division so that each of said new pixels in a section has the same value determined by values of said original pixels in said predetermined vicinity; and a new pixel value determining means (6) for determining the value of said new pixel, according to the values of said original pixels in said predetermined vicinity, and said section which is determined in said section determining means (510).

Claim 16

Independent Claim 277 words

An apparatus for determining values of new pixels which are to be interpolated in a unit area which is surrounded by original pixel centers, when magnifying an image consisting of original pixels, comprising: a new pixel coordinate generating means (1) for generating a coordinate of a center of a new pixel for interpolating between the original pixel centers, according to a magnification rate; a pattern detecting means (4) for detecting one of a plurality of predetermined line images by comparing values of a combination of original pixels in a predetermined vicinity of said unit area with each of predetermined patterns; a selector means (507) for selecting one of a plurality of predetermined modes of division of said unit area according to said one of line images detected in said pattern detecting means (4), wherein said plurality of predetermined modes of division are provided, in advance, corresponding to said predetermined patterns; a section determining means (510, 61, 62) for determining in which section the center of said new pixel is, in accordance with information of lines dividing said unit area in said mode of division which is selected in said selector means (507), wherein said section is one of a plurality of sections which is generated by each of said modes of division so that each of said new pixels in a section has the same value determined by values of said original pixels in said predetermined vicinity; and a new pixel value determining means (6) for determining the value of said new pixel, according to the values of said original pixels in said predetermined vicinity, and said section which is determined in said section determining means (510).

Claim 17

Dependent Claim 62 words

An apparatus according to claim 14, further comprising, a nearest original pixel determining means (41, 42, 44) for determining which one of said pixel centers surrounding said unit area is the nearest to said new pixel the value of which is required to be obtained; wherein said patterns and said vicinity are predetermined for each of said pixel centers surrounding said unit.

Image magnification

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