Method of displaying text on a screen

Claim 1

A method for displaying text and graphics on a display device which comprises a display screen raster with a given number of pixels in x and y direction and a video refresh memory, wherein the glyphs, for example characters and similar graphic symbols, to be displayed are loaded in an outline format from a memory, are scaled, rotated and positioned according to the text processing requirements and wherein the raster points lying on the outline of each glyph are determined by a rasterisation process, e.g. a gridwalk, wherein rasterisation and positioning of the glyphs is done glyph by glyph in a fine raster in which each pixel of the display screen raster is subdivided in x direction into m and in y direction into n fine raster pixels, wherein m, n are natural numbers larger than 1, and wherein each glyph is transformed into a run length code of its outline in which in each fine raster line the start raster position of each stroke in x-direction consisting of at least one filled pixel and the difference between end and start raster position of the stroke are given, and wherein the m × n fine raster pixels in each screen display pixel of each glyph are summed by adding their bit-values by direct calculation from the run length code, and a grey value depending on the sum is allocated to said screen display raster pixel and is written into the video refresh memory which has a bit depth of at least the number of provided grey-values, for example a quarterbyte-, halfbyte- or byte-map memory.

Claim 3

A method according to any of the preceeding claims, wherein the determined grey-value of a display screen raster pixel is written into the video refresh memory by adding it to the content of the memory location corresponding to this display screen raster pixel in the video refresh memory.

Claim 7

A method according to any of the preceeding claims, wherein, when using a colour display screen, the grey steps are generated by uniform excitation of the red, yellow and blue colour centers.

Claim 8

A method for displaying text and graphics on a display device which comprises a display screen raster with a given number of pixels in x and y direction and a video refresh memory, wherein the glyphs, for example characters and similar graphic symbols, to be displayed are loaded in an outline format from a memory, are scaled, rotated and positioned according to the text processing requirements and wherein the raster points lying on the outline of each glyph are determined by a rasterisation process, e.g. a gridwalk, wherein before the begin of a text display all glyphs of a script selected by the user are rastered in a fine raster only once which is in x direction m times and in y direction n times finer than the display screen raster, wherein m, n are natural numbers larger than 1, and wherein each glyph is transformed into a run length code of its outline, in which in each fine raster line the start raster position of each stroke in x-direction consisting of at least one filled pixel and the difference between end and start raster position of the stroke are given, and is stored in an intermediate storage, wherein for text display the fine rastered glyphs are recalled from the intermediate storage according to the text processing requirements and are, according to their position in the text, transferred to a corresponding fine raster position in the display screeen raster, wherein the m × n fine raster pixels in each screen display pixel of each glyph are summed by adding their bit-values by direct calculation from the run length code, and a grey value depending on the sum is allocated to said screen display raster pixel and is written into the video refresh memory which has a bit depth of at least the number of provided grey-values, for example a quarterbyte-, halfbyte- or byte-map memory.