- These are standards set by the ITU-T governing the transmission of video
and communication compatibility.
Recommendation regarding frame-synchronous control and indication signals
for audiovisual systems.
H.221 ITU-T Recommendation regarding frame structure for
H.223 ITU-T Recommendation: Multiplexing Protocol for Low Bitrate
H.231 ITU-T MCU Recommendation for multipoint
control units using channels up to 2 Mbps.
H.242 ITU-T codec Recommendation regarding: System for Establishing
Communication Between AudioVisual Terminals using Digital Channels up to 2
H.243 ITU-T Recommendation: Procedures for Establishing Communication
Between Three or More AudioVisual Terminals using Digital Channels up to 2
H.245 ITU-T Recommendation; Control Protocol for Multimedia
H.261 ITU-T codec
Recommendation regarding a video codec for audiovisual services at p x 64
Kbps. Regrettably, motion compensation and field sub-sampling (loop filter)
are implementation optional in the standard. Users considering an ITU-T
codec for operation at bit rates of 384 Kbps or below should ensure that the
manufacturer has implemented these options.
H.261 Annex D ITU-T codec Recommendation for simultaneous graphics
transmission in the North American region. Other administrations may use JPEG
H.263 ITU-T Recommendation, Video Coding for Low Bitrate
Communication; regarding a video codec for audiovisual services.
Considerably broadens H.261 capabilities, extending from low- resolution,
credit card-size images, to high-quality, exceptional detail images, for
applications such as telemedicine.
Backward compatibility to H.320 QCIF(Quarter
Common Intermediate Format) and, optionally, to CIFand
SQCIF (Sub-QCIF) is provided.
H.320 A series of audio visual communications recommendations which
were ratified by the CCITT in December
1990. The aim of the series, which applies to audio visual communications
over 56/64 Kbps to 2.048 Mbps channels, is to ensure videoconferencing
systems and video terminals will interconnect across any network. H.320 is
an umbrella standard encompassing a series of recommendations, including:
H.321 ITU-T Recommendation describing ATM-based
- H.221 (frame structure for a 64-1920Kbps channel);
- H.230 (frame synchronous control and indication signals);
- H.242 (systems for establishing communications between audio
visual terminals using digital channels up to 2 Mbps);
- H.261 (visual coding for transmission over 56/64-2048 Kbps digital
- G.711 (An ITU-T Recommendation detailing a 32- to 64-Kbps 3.4-KHz
bandwidth audio coding algorithm);
- G.722 (An ITU-T Recommendation detailing a 64-Kbps 7-KHz bandwidth
audio coding algorithm. Part of the ITU-T codec requirements);
- G.728 (An ITU-T Recommendation detailing a 16-Kbps 3.4 KHz
bandwidth audio coding algorithm);
H.322 ITU-T Recommendation describing: Visual Telephone Systems and
Terminal Equipment for Local Area Networks which Provide a Guaranteed
Quality of Service [guaranteed bandwidth]. This standard makes direct
reference to the Draft IEEE P802.9a (which
see). These standards describe LANs which provide low latency, suitable for
H.323 ITU-T Recommendation describing: Visual Telephone Systems and
Terminal Equipment for Local Area Networks
which Provide a NON- Guaranteed Quality of Service
H.324 (suite spec.) ITU-T Recommendation describing a Terminal for
Low Bitrate Multimedia Communication; includes various recommendations
including video codec, for low-speed connections using single or dual V.34
connected to analog POTS, plus ISDN,
ATM and probably mobile, bringing
together other recommendations to produce an overall "visual telephony"
system specification. Some compatibility with H.320, network transcoding and
exceptionally good multipoint support and continuous presence are also
- Health Care Information Infrastructure (HCII)
- A subset of the NII, expected to save the U.S. in the neighborhood of $100
billion given that information processing alone amounts to approximately 20
percent of health care costs. HCII is expected to save health care costs
through development of the following delivery systems:
The evolution of HCII will require development of four main segments of the
current telecommunications infrastructure:
- administrative information systems (HIS)
clinical information systems (CIS)
- personal health information systems (CHINs).
1.transmission lines, i.e., cable TV (CATV) and telephone companies.
SEE ALSO Medical Informatics.
Health Level-7 Data Communications Protocol (HL-7)
- Defines standards for transmitting data for billing, hospital census,
order entries, and results reporting over hospital networks. The protocol is
accepted by most types of host computers. HL-7 allows bedside terminals,
radiological image stations, patient accounting, order entries, and critical
care monitors to be incorporated into a single system. SEE ALSO CPR and
Health Open Systems Trials (HOST)
- A project funded by the National Library of Medicine (NLM)
to develop telemedicine demonstration projects that evidence an Open
Systems approach. Major partners include IBM and Sprint.
Health Services Technology Assessment Text (HSTAT)
- HSTAT is an NIH initiative to develop
national standards of clinical care.
High-Definition TeleVision (HDTV)
- Any of a number of television standards providing an aspect ratio of about
2:1 and resolution far superior to PAL or NTSC.
High Density TeleVision (HDTV)
- High resolution broadcast video. See MPEG-2.
Vertical resolution about 4 times that of a standard television (1,125 lines
compared to 352 lines in a standard NTSC television output) and an aspect
ratio of 16:9, similar to a movie screen.
High pass filter See
- low pass filter
High resolution still imagery
- Still photographs taken with a digitizing camera, compressed into a storm
JPEG format, transmitted via satellite and/or telephone lines, decompressed
and processed in a digital film printer at 200 dots/sq inch.Quality and
color better than regular still photographs. Especially useful for
dermatology telemedicine consults.
Hospital Information System (HIS)
- Provides support for all information processing within the organization
with a focus on adminstrative support (e.g. planning and budgeting,
marketing, personnel, etc.) It integrates the clinical information system
with strategic planning and quality improvement. There is development
underway to apply hypertext technology (such as this document) to Hospital
Information Systems. One example is remote reading and interpretation of
radiographic studies (RIS). For more explanation of this concept, read WWW
and the Electronic Medical Record.
- Provides a cost-effective single point of connection to the network for
workstations and other devices.
- A lossless, statistically-based entropy coding technique used to compress
data in which the most frequently occurring code groups are represented by
shorter codes, and rarely occurring code groups are represented by longer
codes. Used in H.320and other videoconferencing codecs,
Group 3 facsimile and JPEG.
- Human-computer interface technologies make it possible for human beings to
get understandable information in to or out of computers. These can be as
basic as a keyboard and mouse or as complicated as speaking to and computer
and being understood--or receiving a dynamically generated, animated video/audio
presentation of on-line information as an answer to a question. The
technologies include: graphical user interfaces, animation and full-motion
video, optical character recognition (OCR), handwriting recognition, speech
(synthesis and recognition) and natural language (particularly translation)