FR2661305A1 - METHOD OF VISUALIZING IMAGES ON COLOR SCREEN WITH POINT MATRIX. - Google Patents

Abstract

The invention relates to display on a color dot matrix screen. The structure of these screens brings about phenomena that are disturbing for the view, such as the more particularly troublesome stair treads with fine lines rotating around one of their ends. To avoid this and according to the invention, the color of a monochrome zone is chosen such that it is possible to give the pixels (P1, P2) surrounding the zone at least one color close to that of the pixels (P0) of the zone, but with a lower luminance. Application, in particular, to the display of measurements.

Description

i Method for viewing images on a color screen

dot matrix.

  The present invention relates to a visualization method

  on a dot-matrix color screen and in particular on

  such screens used for the visualization of measurements.

  On such a screen it is known to use shades of gray (gray shadows in the Anglo-Saxon literature) to avoid distortion phenomena of the line, staircase type, and phenomena of blinking; these phenomena tend to appear around monochrome areas, being

  understood that any color image, on a screen, is decompo-

  sand in a finite number of monochrome areas By thickening the monochrome strokes and controlling the shades of gray of the screen pixels corresponding to this thickening, for example, by pulse width variation, it is indeed

  possible to avoid these phenomena; but that increases seriously-

  calculations for the elaboration of an image, it harms the fineness of the features of the image and this does not eliminate

  the phenomenon of iridescence on the edges.

  The present invention aims to avoid or, for the

  least, to reduce these disadvantages.

  This is obtained by choosing the colors of the monochrome zones so that it is possible to give the pixels surrounding these zones at least one color close to that of the pixels of the monochrome zone considered but with

a lower luminance.

  According to the invention there is provided a visualization method

  color dot-matrix image display forming identical pixels, consisting of dots, ie dots of the matrix, some of which are associated with color filters and whose apertures are independent of each other. others, characterized in that it consists, to view a monochrome area on the screen, to choose a color that he

  It is possible to obtain, at least approximately,

  first and second way the dots of the pixels with, for the same signal of opening of the dots, a luminance per pixel higher in the case of the first way to that in the case of the second way, to to order in the first way the opening of the dots of the pixels

  located in the area under consideration and in the second way the

  vertex of the dots of the pixels surrounding the zone considered.

  The present invention will be better understood and others

  characteristics will appear from the description below.

  FIG. 1 is a diagram of an on-screen display device that can be used both according to the invention and according to the prior art. FIG. 2 is an enlarged view of a pixel. of the screen according to FIG.

  FIGS. 3a, 3b, 3c are diagrams according to the prior art.

  and gray-free, of a white line on a dot-matrix screen, Figs. 4a, 4b, 4c are plots of the same line as in Figs. 2a, 2b, 2 c, but with thickening of the line according to the prior art, FIGS. 5a, 5b, 5c are plots of the same line as

  in FIGS. 2 and 4 but with a shade of gray according to the invention

  FIGS. 6 and 7 show enlarged views of parts of the screen according to FIGS. 4 and 5, FIGS. 8 and 9, enlarged views corresponding to the plots according to FIGS. 5a, 5b, 5c but with a trait of

  color, respectively green and green-red.

  FIG. 1 is a simplified diagram of a device for

  color display, on a dot-matrix color screen, 1, of images defined by a graphic microcomputer 2 which stores in a random access video memory, 3, called VRAM memory (initials of the English words Video Random

  Access Memory), instructions for drawing information elements

  The video memory 3 has a random access memory.

  A shift register of the parallel-series type and a scanning circuit for automatically and cynically transferring the lines of the random access memory into the shift register. The shift register of the memory 3 provides, line by line, the information to be displayed on the screen This information is received by a driver stage 4

  (driver in the Anglo-Saxon literature) composed of a

  series-parallel followed by a latch (latch

  in Anglo-Saxon literature), which includes as many

  Only points per line of the screen on screen 1 are associated with a line counter 5 which has as many outputs as the screen 1a of lines; this counter authorizes the taking into account, in the lines of the screen for which they are intended, information as and when they arrive in the pilot stage 4 In the example described the screen 1 is a screen of 480 x 480 basic dots or dots, grouped into elements

  image or pixels consisting of four square dots, respectively

  white, green, red and blue when they are lit, that is,

  say when information arrives from the pilot stage while the line they are on is validated by the

line counter 5.

  Figure 2 shows how different colors are obtained from a pixel: each pixel is made of

  four dots, W, G, R, B, arranged in a square, each dot

  carries a point of the matrix, and the three dots G, R, B

  respectively a green filter, a red filter and a blue filter arranged at the front of the screen relative to the points; these

  three filters are in the form of dimension squares

  identical, joined to form three quarters of another square whose fourth quarter, which does not include a filter, is in line with the dot dot W.

  When the screen is illuminated, from behind, with a light

  white, and that the four dots are passers by for the light of the back lighting, the screen delivers, directly above these dots, respectively green, red and blue lights and

  fourth dot, W, which is not associated with a thread.

  be, a white light and the bright spot relative to the pixel is substantially a square But there is a mixture of colors if more than one dot is passing in the pixel

  considered; this is how, when the four dots are not-

  the central part, delimited in Figure 2 by a dashed circle, as well as the whole non

  covered by a filter, is white while the parts covered

  The green of a filter and located outside the circle are of the color of the filters Thus, when a whole surface, which can be reduced to a line, consists of pixels of which all the dots are passing, there occurs a phenomenon of iridescence on

the edges of this surface.

  Regarding the four dots of the same pixel, it should be noted that, because of the filters, for the same illumination of the screen and the same signal of opening of the dots, the luminance in line with the dots G, R , B is four times lower than in line with the

  dot, W, which is not associated with a filter.

  Figures 3a, 3b, 3c show how can be obtained

  naked, according to the prior art, on the screen 1, the image of a representative white line segment, for example, a chronometer hand; this segment rotates around a point 0, in the clockwise direction, and FIGS. 3a, 3b, 3c are

  three successive representations in time of this segment.

  These three figures consist exclusively of pixels whose four dots are passing for the light; each of these pixels of the line segment is therefore symbolized by a hatched square which, as seen with reference to FIG. 2, represents the light spot relative to a pixel of which all

the dots are passing.

  With images according to FIGS. 3a, 3b and 3c the deformers

  Staircase steps are important as is the

  iridescence phenomenon discussed in the description of

of Figure 2.

  FIGS. 4a, 4b, 4c show how, by thickening the line, with respect to FIGS. 3a, 3b, 3c, it is known to

  reduce the effect of steps; but the phenomenon of

  This thickening process consists of surrounding the pixels that formed the straight line segments.

  monochrome figures 3 by pixels providing accurate-

  the same lighting as those of the surrounding pixels, ie

  say a white lighting obtained with the four dots passants.

  To facilitate the understanding of the method, the squares of the pixels, which were already illuminated in the case of FIG. 3, have been hatched in FIGS. 4, and this will also be the case on FIG.

  Figures 5; these hatches are identical to those of the

  On the other hand, and although they provide the same illumination, the pixels which have been added around the periphery of the segments according to FIG. 3 have their squares which are hatched in a

different meaning.

  It should be noted that it is possible to reduce this phenomenon

  of iridescence by means of shades of gray obtained by

  time of opening to the light of dots, for example

  ple by a sawtooth command with some teeth removed or by pulse width command

  adjustable; but such a temporal control seriously complicates

  implementation of the on-screen display device and

therefore makes it more expensive.

  FIGS. 5a, 5b and 5c show how the phenomena of steps of stairs but also of iridescence observed with a

  visualization according to FIG. 3 can be strongly attenuated.

  clouds without searching for a shade of gray by

  For this, the pixels which formed the line segments according to FIG. 3 are surrounded by pixels where only the dot W is conducting; this results in several consequences: the iridescence disappears and the steps are strongly attenuated a shade of gray is obtained around the right segment, the determination of the image requires less calculations on the part of the microcomputer than in the method according to Figures 4; these last two consequences will be studied using figures 6 and 7.

  In FIGS. 5, the pixels o only the dot W, that is,

  say the dowry not associated with a filter, is passing, have been repre-

  squares four times smaller than the squares of

  pixels where all the dots are passing.

  Figure 6 shows the squares of three neighboring pixels, PO P1, P2 each having their four dots passing; this is what happens in FIGS. 4 when a pixel of a segment according to FIG. 3 has been surrounded by pixels to thicken the segment. FIG. 7 shows the squares of three neighboring pixels PO, P1, P2, whose central pixel, PO, has its four dots passing and whose two other pixels, P1, P2, have only the

  dot W who is passing; this is what happens in the figures

  res 5 when a pixel of a segment according to FIGS.

  surrounded by pixels where only the dot W was passing In

  dropping the coefficient 1 to the luminance of a dot associated with a

  filter and, according to what has been said before, the coefficient

  4 the luminance of a dot W, the amount of light provided by the three pixels according to FIG. 6 reaches level 21 while it reaches only level 15 in the case of FIG. 7: the central pixel very bright white is between two less bright white pixels; So there is

  good getting a hue of gray In addition a picture realizes

  by passing only one dot in the pixels surrounding a monochrome surface, asks the microcomputer 2 of FIG.

  there are two, three or four dowries to make passersby in the

  rage of the surface considered Of course there are cases where the

  monochrome surface is made of pixels o only a dot with

  both a filter is passing; these cases must be avoided in order to * 7 be able to surround the surface considered by pixels at least

  approximately the same color but less luminous.

  Thus a green monochrome surface will not be obtained with pixels whose only dot G, which includes a green filter, will be passing, but, for example, with the dots G and W passers to obtain a bright green, and the periphery will be done

  pixels o only the dot G will be passing; Figure 8 shows

  in a line made in this way, a pixel, where the dots G and W are passing, surrounded by two pixels where only the dot G is passing; thus, the luminance is five times higher for the central pixel, since, as previously seen, the dot W has a luminance level four times that of the dots G, R and B Another possibility for to obtain green, but this time red green, will be to make passers, in a central line of pixels, the dots G and R, the entourage then being made of pixels where only the green dot will be passing; this possibility is illustrated by FIG. 9, which represents a first pixel that starts from the central line with its dots G and R passers and two pixels arranged on either side of the central line, around the first pixel, with only their dot G passing; so the luminance of the center line has a level twice

  superior to that of his entourage.

  The invention is not limited to the examples described with reference to the figures which relate to lines; for larger monochromatic surfaces all the pixels of the surface will be controlled as the pixels of the central lines mentioned above, while the pixels of the periphery of this surface will be controlled as the pixels surrounding the pixels.

pixels of a central line.

  The present invention generally relates to any method of viewing a monochrome area on a dot-matrix color screen to select a color that is at least approximately first and secondly depending on the dots composing the pixels of the screen, and with a luminance level per higher pixel in the case of the first way to that in the case of the second way; the method then consists in obtaining the color in the first manner with the pixels of the zone considered and in obtaining the color according to the second

  way with the pixels surrounding the area.

  ILVE NOR DICATIONS 1 Method for displaying color matrix dot-matrix image images forming identical pixels, composed of dots (W, G, R, B), that is to say points of the matrix some of which are associated to color filters whose openings are independent of each other,

  characterized in that it consists, to visualize a mono-zone

  on the screen (1), to choose a color that is possible

  to obtain, at least approximately, by controlling in a first and a second manner the dots of the pixels with, for the same dots opening signal, a luminance per upper pixel in the case of the first way to that

  in the case of the second way, to be ordered according to the first

  first way the opening of the dots of the pixels located in the zone considered and in the second way the opening of the dots

  pixels surrounding the area.

  2 Method according to claim 1, implemented with a screen (1) whose pixels consist of four dots respectively white (W), green (G), red (R) and blue (B),

  characterized in that it consists, to obtain a white color

  check the opening of all the dots of the pixels

  killed in the area considered and to command the only opening of the green dots (G), red (R) and blue (B) pixels surrounding

the area considered.

  Process according to claim 1 carried out with a

  screen (1) whose pixels consist of four dots res-

  respectively white (W), green (G), red (R) and blue (B),

  rised in that it consists, to obtain a green color, to control the opening of the white (W) and green (G) dots.

  pixels in the area and to control the opening

  the green dot (G) of the pixels surrounding the area.

  4 Process according to claim 1, implemented with a screen (1) whose pixels consist of four dots respectively white (W), green (G), red (R) and blue (B), characterized in that it consists, to obtain a green color, to control the opening of the green (G) and red (R) dots

  pixels in the area and to control the

  vertex of the green dot (G) of the pixels surrounding the area considered

SOE.