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A Cab Coefgh U.S ||||||||||||||| USOO51 19082A United States Patent (19) 11 Patent Number: 5,119,082 Lumelsky et al. 45) Date of Patent: Jun. 2, 1992 54) COLOR TELEVISION WINDOW EXPANSION AND OVERSCAN OTHER PUBLICATIONS CORRECTION FOR HIGH-RESOLUTION "Digital Image Processing", by Gregory A. Baxes, pp. RASTER GRAPHICS DISPLAYS 160-161, 1984. Philips Co. SIGNETICS; Digital Video Signal Proces 75 Inventors: Leon Lunnelsky, Stanford, Conn.; sing-Part One. Sung Min Choi, White Plains; Alan Primary Examiner-Alvin E. Oberley W. Peevers, Peekskill, both of N.Y. Assistant Examiner-Amare Mengistu Attorney, Agent, or Firm-Roy R. Schlemmer; Jack M. (73) Assignee: International Business Machines Arnold Corporation, Arnonk, N.Y. 57) ABSTRACT A video pixel presentation rate expansion circuit is pro (21) Appl. No.: 415,012 vided for use with a high-resolution display system. The overall display system includes a high-resolution moni tor, a computer for providing control signals, including 22 Fied: Sep. 29, 1989 a high-resolution frame buffer for storing computer graphics and TV video images and reading out said (51) Int. Cl. ......................... G09G 1/06; H04N 9/74; video data at a rate controlled by said control signals H04N 7/0 and providing said data with a high-resolution monitor 52) U.S. C. .................................... 340/731; 340/703; for display. The expansion circuit of the present inven 340/814; 358/22; 358/140 tion comprises means responsive to an expansion pat 58 Field of Search ....................... 340/717, 814, 731; tern generated by the computer for changing the time 358/22, 140 base of the video pixel data read out of said frame buffer. Circuit includes means responsive to said expan 56 References Cited sion pattern for selectively repeating predetermined scan lines of said video display and for selectively re U.S. PATENT DOCUMENTS peating certain pixel along a given scan line to match 4,063.280 12/1977 Hattorie et al. ............... 358/22 PIP the time base of the video data read out of said frame 4,12,283 10/978 Walker ................................ 340/703 buffer to the time base of said high-resolution monitor. 4,134, 28 M1979 Hurst ................................... 358/60 According to a preferred embodiment of the invention 4,303,986 12/1981 Lans. the expansion circuit functions to modify the control 4,317,1 14 2/1982 Walker . 4,686,580 8/1987 Kato et al. .......................... 358/451 signals which controls the read-out of the frame buffer 4,746,979 5/1988 Kashigi ................................. 358/22 in a predetermined fashion without any additional video 4,746,981 5/1988 Nadan et al. ... 340A717 buffer storage means. 4,821,031 4/1989 Roberts ............ ... 340/731 4,952,923 8/1990 Tamura ............................... 340/731 5 Claims, 5 Drawing Sheets (B-Y) as coa e coef G H cR-Y) a cab coefgh U.S. Patent June 2, 1992 Sheet 1 of 5 5,119,082 TV MACE HGH RESOLUTION MAGE F. G. FG.2A WIS BLE ACTIVE PORTON OF THE SCREEN 62 PELS ACTIVE WIDEO 720 (7Z FG2B Y ACTIVE 480 INES H - RES VIDEO OR H CHER ACTIVE WIDEO (640 PELS) OR HCHER U.S. Patent June 2, 1992 Sheet 2 of 5 5,119,082 FIG,3A PRIOR ART O 2 3 d 4. 5 6 7 ------- ;7 : || ||7 l FIG,3BPRIOR ART 6 6 : 7 7 cB-1) (B-Y)2 - cR-Y). CR-Y)2 - U.S. Patent June 2, 1992 Sheet 3 of 5 5,119,082 FIG,4A PR OR ART A B C DEFGHI A B C DEFGHI (B-Y) A B C D A B C D EFG H (R-YA B C D A B C DEFGHI U.S. Patent June 2, 1992 sheet 4 of s 5,119,082 FIG5 V P X R S 13 O R X S. VXSRC) Cs O V S L R VS C. L. O CK X HXSRCO) VCLK U.S. Patent June 2, 1992 Sheet 5 of 5 5,119,082 FIG 6 WCLK HXSR(0) VIDEO DATA : : FRAMEFM BUFFER - A --8-- - -D-i-E D/AATE DATA - A --B -i- C i-D VIDED VIDED DATA IN 7 DATA OUT VIDE T SOURCE VIDEO DISPLAY 700 702 BUFFER VCLK' VSCLK VBADDR FIG.7 VIDED BUFFER ADDRESS MULTIPLEXER 5,119,082 1 2 store away incoming pixels such that they are not lost, COLOR TELEVISION WINDOW EXPANSION or a mixture of both. AND OVERSCAN CORRECTION FOR It should be noted that as the magnification ratio HIGH-RESOLUTION RASTER GRAPHICS increases, the image quality decreases. For example, DISPLAYS when the magnification ratio is greater than two, the sharpness of the image is greatly reduced. FIELD OF THE INVENTION Nevertheless, for current mixed video/graphics dis play systems, the significance of magnifying television The present invention relates generally to the field of images are of considerable importance. It is especially raster-scan graphic/video display systems. More partic O important due to overscan problems which will be dis ularly, it relates to such display systems which are capa cussed below. ble of displaying interchangeably and/or concurrently In conventional commercial TV systems, the active both high-resolution graphic data and standard lower portion of the raster (i.e., between blank signals) over resolution TV video data on a high-resolution graphics scans the viewing area of the CRT to prevent a black monitor. 15 border under worst-case conditions of variations in yoke sensitivity, anode voltage, etc. (See "Television CROSS REFERENCE TO RELATED Engineering Handbook", McGraw Hill Company, APPLICATIONS 1986, p. 13.177). The overscan requirement for con U.S. patent application Ser. No. 314,998, filed Feb. sumer TV receivers goes somewhat higher than 10% of 24, 1989 of Lunnelsky et al., Entitled "Color-Television 20 the full active area (See FIG. 2). This means that less Window For a Video Display Unit" discloses a video than 90% of the active video image is usually shown on adapter architecture which provides for the expansion a TV screen. It is safe to say that video is overscanned of video data before it is stored in the video frame not more than 15%. This number is taken into consider buffer. It performs the requisite time-base or pixel pre ation when video is edited. sentation rate expansion on the data at the input to the 25 On the other hand, high-resolution graphics monitors video frame buffer and requires significant extra hard do not use an overscan approach. Rather, they are un ware to perform this operation contrasted with the dierscanned in order to present all graphics image pixels present invention. on the screen. In other words, it means that a black border always surrounds the image. BACKGROUND OF THE INVENTION 30 The majority of applications in the multimedia area The mapping of a television image on a graphics overlay a television image with graphics. The most screen generally requires the image to be sampled and widely used approach is to match 85% (in both linear stored into a frame buffer. This allows a time base cor directions) of the active television video with full rection to be provided and, if necessary, a time com lengths of the active graphics video line. With this ap pression of the television image in order to show both 35 proach a multimedia editor can be sure that whatever television and graphics images on the same screen. If television movies or other materials are combined with the image should be positioned in any arbitrary sized graphics, the television image coordinates will corre window on a graphics screen, it should be either scaled spond to the graphics image coordinates with reason up or down. The image itself may not be a full screen able accuracy, and no unnecessary information, which image, but just an arbitrary window inside the full view might be overlooked during editing, will appear on the SC. image. This requires a translation and scaling operation The overscan requirement is also important for pro on the source image. Translation is a simple matter, and viding compatibility with previously developed multi shall not be discussed in this paper. FIG. shows how media programs. For example, millions of dollars are a TV image window, Is, is transposed to a graphics 45 spent on such video processing programs such as IBM screen window, Id. Infowindow, educational and presentation programs, Scaling up a television image on a graphics screen where the overscan is taken into consideration. For a poses a much harder problem than scaling down. When detailed description of the Infowindow product, refer scaling down a source image to a smaller destination ence should be made to one of the following publica image, it is possible to simply ignore pixels in the hori SO tions describing same. zontal direction and ignore scan lines in the vertical 1) “Infowindow Guide to Operations' Order No. direction to achieve the correct sizing at the time of SK2TO297 and, sampling. For example, to achieve a quarter sized win 2) "Infowindow Enhanced Graphics Adapter: Hard dow, every other pixel can be thrown away horizon ware Maintenance and Service Manual' Order No. tally, and every other scan line vertically. This can be 55 SK2TO298, both are available from IBM Corp. done simply at the time of sampling the source image Mechanicsburg, Pa. Any multimedia display into a frame buffer. However, for image expansion, it is adapter which does not address the overscan prob necessary to either replicate pixels in a horizontal direc lem can not be used with Infowindow or Infowin tion or replicate scan lines in a vertical direction to dow-like programs. Moreover, such an adapter can achieve the desired destination window size.
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