Etablissement Public De Diffusion Dit 'telediffusion De France'

Other

France Telecom

L'etat Francais

Telediffusion De France S.a.

Establissement Public De Diffusion Dit 'telediffusion De France'

L'etat Francais, Represente Par Le Ministre Des P.t.t. (centre National D'e

Bernard Marti

Alain Poignet

Roger Brusq

Claude Fournier

Christian Roche

Jean F Barda

Jean-Yves Savary

A method for the coding of images represented by source signals by means of which a luminance signal is formed by linear combination, using positive coefficients of the source signals, and at least one color signal, the luminance and color signals being digitized, sampled at the same resolution, and subjected to a reversible mathematical transformation in the frequency domain. The method comprises the steps of quantizing and assigning a code value to the continuous component and to each component of a set of alternating components of the transformed luminance signal, and quantizing and assigning a code value to only the continuous component of each of the transformed color signals, a set of alternating components being reconstructed by estimation during the decoding for each of the transformed color signals. The method can be applied to color images of any type represented as the superimposition of monochromatic images, whether the images are still images or motion images.

Method for the coding of color images at high compression rate without

A TV receiver is adapted to display either the regularly broadcast video signals or videotext information. The video signals contain their own internal synchronization signals. The videotext information requires locally generated synchronization signals which may be used to replace the normal video internal synchronization signals. The invention provides means for switching between the normally broadcast and the internally generated synchronization signals.

Apparatus to display graphic messages transmitted by videotext systems

Videotex system provided with protection means against transmission errors. It can be used in the transmission and display of data on television recers for entertainment, information or instructional purposes.

Videotex system

A system for transmission and display of texts on a television screen enables a display of a magazine made up of several pages. The packets of data relative to one page are transmitted without being multiplexed with the packets from another page of the same magazine. The data of one page begins with a page flag which is followed by data indicating the number of the page and ends with the flag of the following page. The data from each page is grouped in rows, preceded by a row flag. Each page contains an order row of the data which is operation data and is not used for display. Certain pages contain only the data which is relative to the shape of characters of the alphabet and the pages are not for display. They include in their order rows a specific operation octet which is recognized in the receiver. Responsive to this page, the system switches the subsequent data from the alphabet page towards the writing circuit of one of many shape memories, in order to record there the character shape data.

System for digital transmission and text display

In the disclosed teletext system, the transmitter station broadcasts data cks data from several channels, the data packs being time multiplexed. Each data pack comprises a prefix signal for causing a teletext receiver either to accept the data packs of a selected channel or to reject data packs from other channels. In addition to the prefix, and possibly page flags followed by page numbers and row flags followed by row numbers, the sequence of eight-bit words, transmitted in a pack, may comprise escape eight-bit words which are followed by type identity eight-bit words, themselves followed by a sequence of characters to be displayed in the same type the identity of which is determined by the preceding type identity eight-bit words. Each teletext receiver comprises, a first conventional random access memory storing the coded characters, a second random access memory storing the type identity eight-bit words at the same addresses as those of the characters belonging to the sequence in the first random access memory. A read operation from the first random access memory, for display purpose, is performed at the same time as the read operation from the second random access memory. The output signals of the second memory select a character generator which includes a permanent memory which reads out the shape of those characters which read out from the first random access memory.

Growing community of inventors

Noyal sur Vilaine, France

Bernard Marti