A method and system for generating symbols in real time on a display screen. The method and system can be applied to generating symbols for assisting in aircraft piloting and navigation. For the plotted lines generated on a matrix screen such as a liquid crystal display screen, the visual appearance deteriorates since the eye is sensitive to the steps produced by the matrix array. To improve the appearance, the plotted lines are widened and they are modulated in luminosity and in color. This is done by replacing each point of a theoretical plotted line by a micro-zone of N.times.M points modulated in intensity according to a table of instructed-value coefficients. Coefficients are computed for each point of the widened plotted line on the basis of this table and on the basis of coefficients previously computed for the same points. Rather than recording the computed points in the memory at each time and reading them again in subsequent computations, only the definitively processed points are transmitted to the image memory.

There is provided an output apparatus in which an output resolution can be changed and a memory medium including character information of printing dot patterns is detachable. The memory medium has holding means for storing and holding output density information of dot patterns of characters stored in the memory medium. The apparatus comprises in one embodiment: reading means for reading out the output density information from the memory medium; and changing means for changing the output resolution on the basis of the output density read out by the reading means. When the output density information read out by the reading means differs from the printing resolution of the apparatus itself in the reading mode, the character information of the dot pattern in the memory medium is not used. With the apparatus, even if the number of dots constructing a character is changed, the character pattern can be automatically output at the optimum output resolution.

An improved raster engine adapted to render video data from a frame buffer to one of a plurality of disparate displays is disclosed which comprises an integral bounded video signature analyzer, a hardware cursor apparatus supporting dual scanned displays, programmatic support for multiple disparate display types, multi-mode programmable hardware blinking, programmable multiple color depth digital display interface, and programmable matrix controlled grayscale generation.

A high speed data display routine used in imaging of displays of geographic or other detail depicting, for example, the depth of an ocean, acoustic prediction plots, photographs and logos. The speed is achieved by a process for efficiently mapping the data values to the display matrix. The information processing uses proportional mapping, but only on the two edges of the data matrix. The processing performs substantially fewer calculations during the mapping process, by rely in accordance with certain conventions on straight raw data copying operations using pre-determined counts.

A thermal printing system is disclosed in which a graphic image composed of a succession of lines having the same number of pixels each is scaled both horizontally and vertically by a factor of approximately 1.5 without altering the size of the pixels. The system disclosed replaces each 2 by 2 set of pixels with a 3 by 3 set of pixels. Each 2 by 2 set consists of two immediately adjacent pixels from the same line and the two immediately adjacent pixels from the next succeeding line. The corner pixels of the 3 by 3 set are identical to the four corner pixels of the 2 by 2 set. The intermediate pixels of the first and third lines have densities equal to the average of the densities of the two corner pixels on the same lines of the same set. The three pixels of the second line of the 3 by 3 set have densities equal to the respective averages of the densities of the pixels immediately adjacent to them in the first and third lines. In this manner, a standard 1024 pixel by 1280 pixel graphic image is transformed into a 1536 by 1920 pixel graphic image. When printed by a thermal printer using a FAX head with 8 dot per millimeter resolution, the resulting image loses substantially nothing of importance in the way of definition and is substantially equal in size to one printed with a standard head with 6 dot per millimeter resolution.