00000nam 2200000zi 4500 9.891736 CaOODSP 20221107172952 m o d f cr mn||||||||| 200923s1979 onca o f000 0 eng d CaOODSP eng rda CaOODSP n-cn--- Co24-3/8-699-1979E-PDF Bown, H. G., author. Picture description instructions, PDI, for the Telidon videotex system / by H.G. Bown, C.D. O'Brien, W. Sawchuk and J.R. Storey. Ottawa : Communications Research Centre, 1979. 1 online resource (iii, 71 pages) : illustrations. text txt rdacontent computer c rdamedia online resource cr rdacarrier CRC technical note ; no. 699-E Issued also in French under title: Instructions de description de l'image, IDI, pour le système vidéotex Télidon. "Technology and Systems Branch." "November 1979." Digitized edition from print [produced by Innovation, Science and Economic Development Canada]. Some pages rotated in this copy. "The Telidon Videotex system is a method by which information can be accessed from central data bases by the general public. By the use of a domestic home television receiver augmented by a micro-computer controlled interface device a user can access pages of graphical and textual information over a public common carrier communications facility such as the telephone network, a cable television line or the data may be even encoded into unused space in a broadcast television signal. In order to transmit information to a Telidon terminal, at minimum bandwidth, and in a manner independent of the type of communications channel, a coding scheme was devised which encodes a picture into the geometric drawing elements which compose it. These "Picture Description Instructions" are an alpha-geometric coding model and are based on the primitives of POINT, LINE, ARC, RECTANGLE, POLYGON, point by point BIT encoded images and TEXT encoded as ASCII characters. This document provides a detailed specification of this code as well as a description of the principles which make it independent of communications channel and display hardware"--Abstract, page 1. Issued also in print format. Telidon (Data transmission system) Videotex systems Canada. Image transmission. Communications Research Centre (Canada), issuing body. Instructions de description de l'image, IDI, pour le système vidéotex Télidon / (CaOODSP)9.891737 CRC technical note ; no. 699-E. (CaOODSP)9.882494 PDF 1.69 MB https://publications.gc.ca/collections/collection_2020/isde-ised/Co24/Co24-3-8-699-1979-eng.pdf