The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 24, 1986
Filed:
Aug. 12, 1985
Michael D Carr, Ipswich, GB;
British Telecommunications, , GB;
Abstract
A conditional replenishment video data transmission system involves the transmission of digital values representing the brightness changes at picture elements of a raster scanned image since the previous frame. Since nothing is transmitted for those picture elements without a significant brightness change, the amount of data to be transmitted will depend on the extent of movement in the image, and buffer stores are provided to allow the use of a constant transmission rate. If the extent of movement in the image is very high the buffer store at the receiver will tend to fill up and might overflow. In order to avoid this occurring, reduction of the amount of data to be transmitted by element subsampling has been proposed in which in a cluster of changing elements data relating to only some, for example alternate ones, of the elements are transmitted, and interpolation is used at the receiver to calculate the brightness change data for the omitted elements. The blurring of vertical edges in the image resulting from the interpolation is avoided by suspending sub-sampling where vertical edges are detected in the image. When in the sub-sampling mode, in order to avoid having to mark those normally omitted elements for which data are transmitted the receiver is arranged to detect the presence of a vertical edge and respond by treating the data as if they relate to all elements in the vicinity of the edge and not just the sub-sampled ones. Transmission error can result in the receiver being incorrect in the detection of edges, and to avoid this the number of quantizing levels during sub-sampling is reduced from 8 to 4, using one set of 4 codes for the normally present elements and the other set of 4 codes for the normally omitted elements. Since a vertical edge will usually appear in more than one line, the receiver may be arranged to check the previous line for a vertical edge and anticipate the inclusion of normally omitted elements if such an edge has occurred.