A Compatible High-Definition Television System using the Noise-Margin Method of Hiding Enhancement Information

This paper discloses a novel method of hiding enhancement information in a normal television signal. A receiver-compatible EDTV system is described based on this method, as well as on a method of conforming the 16:9 aspect ratio of the EDTV system to the 4:3 aspect ratio of NTSC without using side panels. Finally, a scheme for hiding digital audio in chrominance is discussed. The three techniques are independent. — It is found that when video signals are transmitted in the usual over-the-air channels, if the SNR is satisfactory at the receiver, it is actually higher than required in some spatial-frequency bands. This ‘noise margin’ provides a place to add a large amount of extra information. The additional video information is hidden in such a way that the added signal appears on NTSC receivers as low-level additive random noise, processed and distributed so as to minimize its visibility, while at the same time achieving the maximum possible SNR of the hidden information. On a special EDTV receiver, the second signal is detected independently, combined with the first signal, and displayed at high resolution. The method does require a channel SNR high enough to make good NTSC pictures; however, an adequate SNR is required for any method of transmitting high-quality NTSC-compatible EDTV/HDTV images through analog channels. — As an alternative to transmitting side panels, a wide aspect ratio on the EDTV display is achieved by discarding a portion of the height of the transmitted image as displayed on a normal receiver, having previously ensured that the areas so discarded are free of significant content. Thus, both screens can be completely filled, but the appearance on the EDTV display is favored, since the image is originally composed for the wide screen, in the same manner as in 1.85:1 film, and possibly visible seams are avoided. — It is shown that the NTSC chrominance channel has excess temporal and vertical resolution. At the cost of a very small decrease in luminance resolution on today's most expensive receivers, a scheme is introduced for transmitting digital audio in the excess temporal bandwidth. The excess vertical chrominance resolution is used to increase chrominance horizontal resolution, which is very low in NTSC. These methods are useable independently of the noise-margin method for increasing luminance resolution and aspect ratio, and could be added to today's system, although not to existing receivers.

Published

1989-02

Content type

Original Research

DOI

10.5594/M00760

ISBN

978-1-61482-918-8