High speed image drawing method and apparatus therefor

Claim 3

An image drawing method according to claim 1, wherein in the step (e), the number of pixels forming said segment is incremented so as to extend the length of said segment while said auxiliary line extending toward said desired image does not intersect said desired image, and a starting pixel of a next segment is determined when said auxiliary line intersects said desired image.

Claim 4

An image drawing method according to claim 1, wherein said orthogonal directions are X-axis and Y-axis directions in an orthogonal X-Y coordinate system, if the tangent of a tangential line at a point of said desired image corresponding to a starting pixel of a segment is greater than 1 or not greater than -1, the segment and said auxiliary line are extended along the Y-axis direction, and if the tangent of a tangential line at a point of said desired image corresponding to a starting pixel of a segment is greater than -1 and not greater than 1, the segment and said auxiliary line are extended along the X-axis direction.

Claim 5

An image drawing method according to claim 1, wherein said auxiliary line is shifted by 1/2 of an interval between the adjoining pixels from a position of the starting pixel of a corresponding segment and extended toward said desired image along the direction of the corresponding segment.

Claim 6

An image drawing method according to claim 3, wherein the position of an ending pixel of a segment is spaced from a starting pixel of a next segment by an interval of pixels in the X-axis direction and by an interval of pixels in the Y-axis direction, so long as there exists another segment to be drawn.

Claim 7

An image drawing device comprising: an image display device having an image output region including a plurality of pixels arranged in an orthogonal X-Y matrix form; means, including an image screen buffer having a plurality of memory cell locations, each of which corresponds to a respective pixel in said image output region, for reaching out the content of said image screen buffer to transfer the content to said image display device; a plurality of registers for storing parameters required to draw a desired image; memory means for storing at least a program of a drawing procedure; and processor means connected to said image screen buffer, said register and said memory means, for executing said program by calculating the tangent of a tangential line at a position of said desired image corresponding to a position of a starting pixel from which a segment should be started; selecting a line of pixels along one of X-axis and Y-axis direction determined on the basis of the inclination indicated by said calculated tangent; determining an auxiliary line in parallel with the selected pixel line; determining a number of pixels in the selected pixel line so as to form a segment whose length is determined at an intersection of said auxiliary line with said desired image; writing image data of a plurality of segments thus obtained in said image screen buffer; and drawing said plurality of segments on said image display device on the basis of the image data as an approximation of said desired image.

Claim 8

An image drawing device comprising: an image display device having an image output region including a plurality of pixels arranged in an orthogonal X-Y matrix form; means, including an image screen buffer having a plurality of memory cell locations, each of which corresponds to a respective pixel in said image output region, for reaching out the content of said image screen buffer to transfer the content to said image display device; a plurality of registers for storing parameters required to draw a desired image; memory means for storing at least a program of a drawing procedure; and processor means connected to said image screen buffer, said register and said memory means, for executing said program by calculating the tangent of a tangential line at a position of said desired image corresponding to a position of a starting pixel from which a segment should be started; selecting a line of pixels along one of X-axis and Y-axis direction determined on the basis of the inclination indicated by said calculated tangent; determining an auxiliary line in parallel with the selected pixel line; determining a number of pixels in the selected pixel line so as to form a segment whose length is determined at an intersection of said auxiliary line with said desired image; writing image data of a plurality of segments thus obtained in said image screen buffer; and drawing said plurality of segments on said image display device on the basis of the image data as an approximation of said desired image.