Method and apparatus for display of text on screens

Claim 3

A method according to claim 1, wherein the grey-value of each screen pixel is determined as proportional to the sum of black fine-pixels positioned in the respective screen pixel.

Claim 4

A method according to claim 1, wherein m=8 and n=4.

Claim 5

A method according to claim 1, wherein m=4 and n=4.

Claim 8

A method as in claim 5 wherein the grey-value of each screen pixel is determined as proportional to the sum of black fine-pixels positioned in the respective screen pixel.

Claim 9

A method as in claim 5 wherein m=8 and n=4.

Claim 10

A method as in claim 5 wherein m=4 and n=4.

Claim 11

Apparatus for displaying text and graphics on a video display device comprising a screen with a display raster having a given number of pixels in the x- and a given number of consecutive lines in the y-direction, and a video refresh memory, said apparatus using glyphs formatted in an intelligent outline description which are loaded from memory on demand and scaled, rotated, and positioned according to text processing requirements and rastered by pixels being located along their contours, said apparatus comprising: means for rasterising each glyph as it appears in the text processing requirements as necessary, in a high resolution fine-raster in which each screen pixel is more finely resolved with m fine-pixels in the x- and n fine-pixels in the y-direction, m and n being integers larger than 1, and in which each glyph is represented as run length code and stored in a cache-memory describing the positions of start and end transitions between white and black glyph strokes in the fine-raster, means for determining, depending on each glyph's position as provided by the text processing requirements, one out of m×n different positions of said stored fine-rastered glyph relative to the screen raster, there being m×n different possible positions for the fine-pixels of the glyph to fall as groups of m×n fine-pixels into respectively corresponding single screen pixels, means for summing, for each screen pixel, the group of m×n fine-pixels failing in said screen pixel by calculating from start positions and end positions to determine a grey-value for said screen pixel, depending on the sum of black fine-pixels in relation to the number of m×n fine-pixels in register with said screen pixel at said determined position, and means for storing the determined grey value in the video refresh memory thus providing one out of m×n possible glyph variants from each cache-stored, fine-rastered glyph.

Claim 12

Apparatus for displaying text and graphics on a video display device comprising a screen with a display raster having a given number of pixels in the x- and a given number of consecutive lines in the y-direction, and a video refresh memory, said apparatus using glyphs formatted in an intelligent outline description which are loaded from memory on demand and scaled, rotated, and positioned according to text processing requirements and rastered by pixels being located along their contours, said apparatus comprising: means for rasterising each glyph as it appears in the text processing requirements as necessary, in a high resolution fine-raster in which each screen pixel is more finely resolved with m fine-pixels in the x- and n fine-pixels in the y-direction, m and n being integers larger than 1, and in which each glyph is represented as run length code and stored in a cache-memory describing the positions of start and end transitions between white and black glyph strokes in the fine-raster, means for determining, depending on each glyph's position as provided by the text processing requirements, one out of m×n different positions of said stored fine-rastered glyph relative to the screen raster, there being m×n different possible positions for the fine-pixels of the glyph to fall as groups of m×n fine-pixels into respectively corresponding single screen pixels, means for summing, for each screen pixel, the group of m×n fine-pixels failing in said screen pixel by calculating from start positions and end positions to determine a grey-value for said screen pixel, depending on the sum of black fine-pixels in relation to the number of m×n fine-pixels in register with said screen pixel at said determined position, and means for storing the determined grey value in the video refresh memory thus providing one out of m×n possible glyph variants from each cache-stored, fine-rastered glyph.

Claim 13

Apparatus according to claim 9 wherein the grey-value of each screen pixel is determined as proportional to the sum of black fine-pixels positioned in the respective screen pixel.

Claim 14

Apparatus for displaying text and graphics on a video display device comprising a screen with a display raster having a given number of pixels in the x- and a given number of consecutive lines in the y-direction, and a video refresh memory, said apparatus using glyphs formatted in an intelligent outline description which are loaded from memory on demand and scaled, rotated, and positioned according to text processing requirements and rastered by pixels being located along their contours, said apparatus comprising: means for rasterising each glyph as it appears in the text processing requirements as necessary, in a high resolution fine-raster having horizontal scan lines, in which each screen pixel is more finely resolved with m fine-pixels in the x- and n fine-pixels in the y-direction, m and n being integers larger than 1, and in which each glyph is represented in a run length code describing the positions of start and end transitions between white and black of each of its black strokes in the fine-raster and stored in a cache-memory, means for determining, depending on each glyph's position as provided by the text processing requirements, one out of m×n possible different positions of said stored fine-rastered glyph relative to the screen raster, which m×n possible positions to m×n different ways for the fine-pixels of the glyph to fall as respective groups of m×n fine-pixels into respective screen pixels, means for using for each pair of said start and end positions, to directly determine the corresponding start and end pixel of the screen and the number of filled fine-raster pixels contained therein and to add m-filled fine-raster pixels for all screen pixels between such determined start and end pixels of the screen to previously stored values therein including either preceding fine-raster scanlines of the same character or screen-pixel values of preceding characters into the video refresh memory to determine screen pixel grey values, said video refresh memory having a bit-depth sufficient to store the desired number of grey shades.

Claim 15

Apparatus for displaying text and graphics on a video display device comprising a screen with a display raster having a given number of pixels in the x- and a given number of consecutive lines in the y-direction, and a video refresh memory, said apparatus using glyphs formatted in an intelligent outline description which are loaded from memory on demand and scaled, rotated, and positioned according to text processing requirements and rastered by pixels being located along their contours, said apparatus comprising: means for rasterising each glyph as it appears in the text processing requirements as necessary, in a high resolution fine-raster having horizontal scan lines, in which each screen pixel is more finely resolved with m fine-pixels in the x- and n fine-pixels in the y-direction, m and n being integers larger than 1, and in which each glyph is represented in a run length code describing the positions of start and end transitions between white and black of each of its black strokes in the fine-raster and stored in a cache-memory, means for determining, depending on each glyph's position as provided by the text processing requirements, one out of m×n possible different positions of said stored fine-rastered glyph relative to the screen raster, which m×n possible positions to m×n different ways for the fine-pixels of the glyph to fall as respective groups of m×n fine-pixels into respective screen pixels, means for using for each pair of said start and end positions, to directly determine the corresponding start and end pixel of the screen and the number of filled fine-raster pixels contained therein and to add m-filled fine-raster pixels for all screen pixels between such determined start and end pixels of the screen to previously stored values therein including either preceding fine-raster scanlines of the same character or screen-pixel values of preceding characters into the video refresh memory to determine screen pixel grey values, said video refresh memory having a bit-depth sufficient to store the desired number of grey shades.

Claim 16

Apparatus as in claim 11 wherein the grey-value of each screen pixel is determined as proportional to the sum of black fine-pixels positioned in the respective screen pixel.

Claim 17

Apparatus as in claim 11 wherein m=8 and n=4.

Claim 18

Apparatus as in claim 11 wherein m=4 and n=4.