NHK has developed a system for computer generation of Japanese Sign Language (JSL) graphics for meteorological information. As JSL is a different language from Japanese, persons whose first language is JSL have been demanding more TV programmes with sign language in addition to the closed caption services.

The JSL CG system automatically generates animations from the telegrams distributed by the Japan Meteorological Agency so that the user can immediately see the latest meteorological information on the Internet.

In addition, we are now working on development to adapt the system to the NHK Hybridcast, which is the integrated broadcast and broadband system in Japan.

A major issue for the CG animations to be accepted by persons who use JSL for their daily communication is that the automatically generated hand movements of the animated characters connecting the sign language words may seem unnatural. Therefore we have developed a new method for connecting and interpolating between sign language word motions.


As the sole public broadcaster in Japan, NHK strives to rectify the so-called information gap that creates social barriers. In Japan, many people with inherent impaired hearing use Japanese Sign Language (JSL) as their first language. JSL has a distinctive grammatical structure that is linguistically different from spoken Japanese.

Consequently, to assure accessibility to broadcast programmes for the deaf persons, the number of broadcast programmes with sign language should be increased in addition to increasing the number broadcasts with closed captions.

However, in Japan, the ratio of sign language broadcasting time to all broadcasting time is still low (see Figure 1) (1). It is noteworthy that even as the ratio of closed captioned broadcasting time has been increasing over the last few years, the ratio of sign language broadcasting time has hardly increased.

However, increasing the ratio of sign language broadcasting time is difficult because it is necessary to ensure enough sign language casters who can handle programme production.

Technically speaking, as information and communication technology has advanced, multiple communication services have become available. Developing communication support technologies using sign language and making those technologies available to the public are thought to be linked to the social momentum demanding strengthening of information support for the hearing impaired.

While continuing broadcasts with sign language provided by human JSL casters, NHK is advancing research and development on sign language computer graphics (CG) at the Science & Technology Research Laboratories.

If sign language CG can be available, for example, at times when human JSL casters are unavailable such as in the middle of the night, it will be possible to provide emergency broadcasts with sign language attached. Aiming to provide useful information correctly, NHK has set up an Internet site concerning meteorological information.

Moreover, exploiting the characteristics of CG, which are different from those of a real life picture, would enable flexible practices such as utilization of sign language CG for guidance signs in public offices (2) and for sign language education (3).

The present report describes the target and current achievement of the sign language CG research by NHK. Several technologies are described, such as ones close to practical utilization (like the sign language CG automatic production system based on XML formalized information) as well as technologies at a stage of development. Linking these technologies will realize sign language CG for regular TV programmes.


In Japan, although research on artificial sign language started as early as in 1992 (4), its applications have not been widely adopted. Considering this situation, the following three factors can be said to be essential in putting sign language CG to practical use.

1: Presenting sign language CG to the public and gathering assessments

Numerous factors dictate the quality of sign language CG, including: a grammatical factor determining whether the sign language sentence is correct; a technological factor determining whether movements of generated animations are natural; and a subjective factor determining whether the external appearance of a CG character is to a person’s liking.

As for improving sign language CG, these quality determining factors need to be distinguished. To distinguish the subjective factor, the opinions of as many people as possible must be collected and evaluated.

Conventionally, to evaluate test CG images, subjects’ opinions are gathered in a laboratory environment. However, it is not easy to invite enough deaf persons as subjects for evaluation, while experiments with insufficient subjects could result in inadequate accuracy.