EP0413483A2 - Système d'affichage - Google Patents

Système d'affichage Download PDF

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Publication number
EP0413483A2
EP0413483A2 EP90308591A EP90308591A EP0413483A2 EP 0413483 A2 EP0413483 A2 EP 0413483A2 EP 90308591 A EP90308591 A EP 90308591A EP 90308591 A EP90308591 A EP 90308591A EP 0413483 A2 EP0413483 A2 EP 0413483A2
Authority
EP
European Patent Office
Prior art keywords
palette
colour
data
sub
pixel
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP90308591A
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German (de)
English (en)
Other versions
EP0413483A3 (en
EP0413483B1 (fr
Inventor
Dan Shmuel Chevion
Eugeniusz Walach
Ittai Gilat
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
International Business Machines Corp
Original Assignee
International Business Machines Corp
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Publication date
Application filed by International Business Machines Corp filed Critical International Business Machines Corp
Publication of EP0413483A2 publication Critical patent/EP0413483A2/fr
Publication of EP0413483A3 publication Critical patent/EP0413483A3/en
Application granted granted Critical
Publication of EP0413483B1 publication Critical patent/EP0413483B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G5/00—Control arrangements or circuits for visual indicators common to cathode-ray tube indicators and other visual indicators
    • G09G5/02—Control arrangements or circuits for visual indicators common to cathode-ray tube indicators and other visual indicators characterised by the way in which colour is displayed
    • G09G5/06—Control arrangements or circuits for visual indicators common to cathode-ray tube indicators and other visual indicators characterised by the way in which colour is displayed using colour palettes, e.g. look-up tables

Definitions

  • the present invention relates to a display system for displaying images on a raster-scanned cathode ray tube (CRT).
  • CRT cathode ray tube
  • bit map or refresh buffer is employed to store data representing the image to be displayed. This data is output to digital to analog convertors (DACs) to control the intensity of an electron gun(s), and hence the nature of the image as it appears on screen.
  • DACs digital to analog convertors
  • bit map data merely dictates whether the electron gun is active.
  • data may be stored referring both to the intensity of red, green and blue colour components, and the overall luminance or intensity of the pixel.
  • Source colour data stored within a bit map is usually divided into its red, green and blue (RGB) components, a set number of bits being assigned to each colour.
  • RGB red, green and blue
  • 24 bits of data are stored at each bit map location, 8 bits being assigned to each of the three colour components which when combined form the final pixel colour on screen.
  • data from the bit map can be supplied directly to DACs that control the three electron guns within the system (one for each colour), the final colour of each individual pixel on screen being a mixture of the three colour components generated by each gun.
  • many systems include a palette or look-up table.
  • the palette stores data which corresponds to a series of colours, the bit map data being used to address particular locations within the palette.
  • the final colour of the pixel on screen is a mixture of RGB components, but the guns are controlled, via the DACs, by the data stored in the palette.
  • the palette In modern systems, such as those in the IBM PS/2 (Trade Mark) family, the palette has an 8 bit address. Thus the system has 256 possible colours to display on screen at any one time.
  • the PS/2 (Trade Mark) computers are typical in that 18 bits of data are stored in each palette location ready to be supplied to the DACs, 6 bits for each of the primary colour components.
  • a typical display system must overcome two problems; firstly which colours to place within the palette (for example, with 18 bits of data at each location, there are 2**18 possible colours that could potentially be placed within the palette) and, secondly, how to transform source data such that it can address the palette.
  • the first problem stems from the fact that normally only a single palette is available for the entire screen.
  • IBM Technical Disclosure Bulletin Vol. 26, No. 7A, P3409-3418 does describe a system where more than one look-up table is utilised, such that multiple applications can share the same screen.
  • the screen is divided into discrete areas or viewports, each individual look-up table being asigned to one or more of these viewports, and containing data pertaining to a particular application.
  • the system does not include a "universal" palette, that is one palette containing data for all applications for controlling the display in any section of the screen.
  • the essence of the present invention is to provide a display system that allows the rapid presentation on screen of quality images, without the need for extensive image preprocessing, or reloading of the palette.
  • a display system comprising a bit map for storing source data for an image pixel, a palette containing data for controlling pixel colour on screen, logic for addressing the palette, wherein the palette is a universal palette divided into sub-palettes, at least one sub-palette containing data for controlling pixel colour for display anywhere on screen, said data corresponding to shades of dominantly one colour, wherein the data within said sub-palette are addressed via an index generated from an associated portion of the source data.
  • the invention avoids the need to reload the palette for different applications.
  • the screen can be utilised for several different applications at the same time, all applications utilising the same universal palette.
  • An additional benefit is that many more shades of a particular colour are available for display than in a conventional display system, hence removing the need for error diffusion or other dithering techniques to be applied to the data prior to display, in order to remove contouring effects. This is of particular value when a grey-scale image is to be displayed.
  • the image pixels are grouped to form a macro-pixel, wherein the portion of source data utilised to generate the index to address a sub-palette and the sub-palette addressed are dependent on the position of the image pixel within the macro-pixel (M).
  • M macro-pixel
  • the source data includes red (r), green (g) and blue (b) source data and the palette is divided into a first, a second, a third and a fourth sub-palette, the first sub-palette for storing red colour data, the second for storing green colour data, the third for storing blue colour data, and the fourth for storing grey colour data.
  • Logic is included for selecting colour component data to be supplied to index generation logic such that the red colour component source data is utilised to address the sub-palette storing dominantly red colour data, blue colour component source data to address the sub-palette storing dominantly blue colour data and the green colour component source data to address the sub-palette storing dominantly green colour data.
  • all source data can be utilised to generate the index to the sub-palette.
  • the display system can be implemented in the form of a general purpose computer, for example a personal computer, including a key­board and/or other user-input devices, memory, a processor, a display adapter and display device. It could also be implemented as a display adapter card for use, for example, with such a general purpose computer.
  • a method for processing image pixel data wherein a palette is divided into sub-palettes, at least one sub-palette containing data for controlling pixel colour anywhere on screen, said data corresponding to shades of dominantly one colour, wherein the sub-palette is accessed by an associated portion of image pixel source data.
  • RGB colour components are mixed in varying proportions in order to yield a composite colour for each pixel as it appears on screen.
  • the source data is manipulated such that the nearest colour approximation available is chosen from the palette.
  • Figure 1 shows a conceptual unit cell model of colour, where each of the axes represents one of the main RGB colour components.
  • the colours represented by an equal mixture of these three components lie along the diagonal axis (dotted line), and are various shades of grey.
  • the present invention utilises a universal palette, that is one palette for all applications, divided into sub-palettes.
  • the palette is divided into four sub-palettes, each with 64 entries, making 256 entries in total, the output of each sub-palette being devoted to shades of one particular colour; for example, red for sub-palette 1, green for sub-palette 2, blue for sub-palette 3 and grey for sub-palette 4.
  • 64 shades of each colour are stored within the palette and are available for display on screen.
  • FIG. 2 shows an embodiment where the macro-pixel (M) consists of four pixels, a,b,c and d. Pixel 'a' is converted according to palette 2 (it is green), 'b' according to palette 1 (red), 'c' by palette 3 (blue) and 'd' by palette 2 (green).
  • M macro-pixel
  • the guns are aimed at individual pixels grouped to form one picture element.
  • the eye then acts to merge the individual colours, thus forming the desired composite colour for that picture element (or macro-pixel). Due to the human eye's greater sensitivity to the colour green, it is desirable for a greater number of individual pixels within a macro-pixel to be devoted to green shades, rather than to either of the alternative colours.
  • Figure 3 illustrates part of the logic of a display adapter for a personal computer in which a multi-colour picture is to be produced on screen and 24 bits of source colour data (8 bits each for RGB) are available at each bit map location in the display buffer of the display adapter.
  • the colour component utilised to address the palette must be "selected", and then used to generate an index to the "physical" palette (Fig 3).
  • Colour source data (r,g,b) is supplied from the display buffer to select component logic (1).
  • Least significant bit data LSB(x) and LSB(y) is supplied from the Cathode Ray Tube Controller (CRTC) of the display adapter to the select component logic (1) during scanning of the display screen (not shown).
  • CRTC Cathode Ray Tube Controller
  • the least significant bit data identifies which pixel (a,b,c or d) within a macropixel (M) is currently being scanned.
  • This LSB data is used to select the appropriate colour component data (r, g or b) to be supplied to the index generator logic (2), which utilises these data to access a particular sub-palette, or portion of the palette (3).
  • the output (R,G,B) from the palette is used to control a colour display device (not shown) connected thereto.
  • the display buffer, the CRTC and other elements of the display adapter which are not shown, can be conventional. Accordingly these elements will not be further described herein.
  • x and y coordinates correspond to the coordinates of the pixel on screen (4).
  • the least significant bits (LSB) of data defining the pixel x,y coordinate change from 0 to 1 alternating with each column or row respectively.
  • LSB values are supplied to logic (1 in Fig. 3) to select the colour data utilised to generate the palette index (via logic block 2).
  • Fig. 5 illustrates the selection process.
  • the index generator (2) must utilise this data to generate an index to a palette address in the desired portion, or sub-palette, of the main palette (3), in order that the pixel be the desired colour.
  • P represents the total size of the palette (in this case 256), Pr, Pg, Pb and Pl the size of the red, green, blue and grey (l represents luminance) sub-palettes respectively (in this example they would all be 64)
  • I Pr + Pg + ((Pb/P).b) where b represents the blue colour data at location x,y.
  • the green colour data accesses the section of the palette containing data yielding a green shade when output to the DAC, the red data a red shade and blue data the section of palette, or sub-palette, yielding a blue shade.
  • pixels could be grouped in many different ways to form macro-pixels (an embodiment is illustrated in Fig. 6), the associated processing of the pixel data being modified to generate the correct combinations of individual pixel colours to form the macro-pixel (
  • Fig. 7 illustrates the processing if the image were to be displayed in black and white (that is a grey-scale rather than a multi-coloured image were desired).
  • the pixel "colour” is not dependent on its position on screen; the pixels are not grouped to form a macro-pixel. There is no need to select a colour component for generating the index to the palette (I).
  • a display system could incorporate both the present invention and traditional image processing technigues, such that image processing could be tailored to meet the needs of the particular application.
  • some shades of a particular colour within the palette could be desaturated, that is a component of the other colours incorporated into that section of the palette, in order to add to the brightness of that colours pixels (that is those pixels whose colour depends on the contents of that particular colour's section of the palette).
  • green would be likely to be chosen for desaturation and the associated increased brightness as this is the optimum colour that the eye can detect.
  • Figure 3 for processing the data output from the display buffer of a display adapter for addressing a palette
  • an alternative embodiment could comprise logic (hardware or software) for preselecting the colour component data for respective screen pixels and storing this in the display memory of a display system.
  • the select component logic and the index generator logic of Figure 3 would not be required, the palette being addressed directly by the contents of the display memory.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Controls And Circuits For Display Device (AREA)
  • Digital Computer Display Output (AREA)
EP90308591A 1989-08-14 1990-08-03 Système d'affichage Expired - Lifetime EP0413483B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IL91303 1989-08-14
IL91303A IL91303A0 (en) 1989-08-14 1989-08-14 System for displaying images on a cathode ray tube

Publications (3)

Publication Number Publication Date
EP0413483A2 true EP0413483A2 (fr) 1991-02-20
EP0413483A3 EP0413483A3 (en) 1991-08-21
EP0413483B1 EP0413483B1 (fr) 1994-11-02

Family

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Family Applications (1)

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EP90308591A Expired - Lifetime EP0413483B1 (fr) 1989-08-14 1990-08-03 Système d'affichage

Country Status (4)

Country Link
EP (1) EP0413483B1 (fr)
JP (1) JPH0377995A (fr)
DE (1) DE69013805T2 (fr)
IL (1) IL91303A0 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0476974A2 (fr) * 1990-09-19 1992-03-25 Sony Corporation Appareil de traitement de données d'images
US5469190A (en) * 1991-12-23 1995-11-21 Apple Computer, Inc. Apparatus for converting twenty-four bit color to fifteen bit color in a computer output display system
WO2000036825A1 (fr) * 1998-12-15 2000-06-22 Koninklijke Philips Electronics N.V. Dispositif d'affichage a representation amelioree des niveaux de gris

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3672586B2 (ja) 1994-03-24 2005-07-20 株式会社半導体エネルギー研究所 補正システムおよびその動作方法
JP2008070404A (ja) * 2006-09-12 2008-03-27 Sharp Corp 液晶表示装置
CN104407832B (zh) * 2014-11-28 2017-05-24 广东欧珀移动通信有限公司 数据处理方法、数据处理装置以及终端

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0202426A2 (fr) * 1985-04-15 1986-11-26 International Business Machines Corporation Dispositif numérique d'affichage à balayage àtrame
EP0210423A2 (fr) * 1985-07-04 1987-02-04 International Business Machines Corporation Système d'affichage d'images en couleur
US4800375A (en) * 1986-10-24 1989-01-24 Honeywell Inc. Four color repetitive sequence matrix array for flat panel displays

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4225861A (en) * 1978-12-18 1980-09-30 International Business Machines Corporation Method and means for texture display in raster scanned color graphic
JPS57144590A (en) * 1981-03-03 1982-09-07 Fujitsu Ten Ltd Color picture display
JPS60486A (ja) * 1983-06-04 1985-01-05 富士通テン株式会社 カラ−画像の表示方法

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0202426A2 (fr) * 1985-04-15 1986-11-26 International Business Machines Corporation Dispositif numérique d'affichage à balayage àtrame
EP0210423A2 (fr) * 1985-07-04 1987-02-04 International Business Machines Corporation Système d'affichage d'images en couleur
US4800375A (en) * 1986-10-24 1989-01-24 Honeywell Inc. Four color repetitive sequence matrix array for flat panel displays

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0476974A2 (fr) * 1990-09-19 1992-03-25 Sony Corporation Appareil de traitement de données d'images
EP0476974A3 (en) * 1990-09-19 1993-01-13 Sony Corporation Method and apparatus for processing image data
US5347621A (en) * 1990-09-19 1994-09-13 Sony Corporation Method and apparatus for processing image data
US5469190A (en) * 1991-12-23 1995-11-21 Apple Computer, Inc. Apparatus for converting twenty-four bit color to fifteen bit color in a computer output display system
WO2000036825A1 (fr) * 1998-12-15 2000-06-22 Koninklijke Philips Electronics N.V. Dispositif d'affichage a representation amelioree des niveaux de gris

Also Published As

Publication number Publication date
DE69013805T2 (de) 1995-05-18
EP0413483A3 (en) 1991-08-21
JPH0377995A (ja) 1991-04-03
EP0413483B1 (fr) 1994-11-02
DE69013805D1 (de) 1994-12-08
IL91303A0 (en) 1990-03-19

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