Digital Signal Processing Pioneer Bede Liu Dies At 91

Bede Liu, a pioneering figure in digital signal processing, passed away at the age of 91 on May 7. Renowned as one of the founders of modern digital signal processing, Liu's work applied mathematical algorithms to analyze, modify, and transmit various types of signals, including sound, images, and video. As an IEEE Life Fellow, he dedicated over five decades to teaching electrical engineering at Princeton University.

From 1994 to 1997, Liu served as the chair of Princeton's electrical and computer engineering department. His groundbreaking research laid the foundation for the transition from analog to digital processing of sound, images, and video, ultimately contributing to the development of many mathematical and engineering techniques that are integral to modern communications, multimedia systems, and consumer electronics.

Although relatively unknown outside of engineering circles, Liu's innovations are embedded in the technologies that billions of people use daily. His low-power digital signal processors, developed in the 1970s and 1980s, are crucial for enabling cellphone calls, streaming video, and internet communications.

In 2018, Liu received the IEEE Jack S. Kilby Signal Processing Medal for his "sustained contributions to the analysis and development of low-complexity realizations of digital signal processing algorithms." His impact was acknowledged by H. Vincent Poor, an IEEE Life Fellow and professor of electrical and computer engineering at Princeton, who described Liu as an "impactful scholar and teacher" who always anticipated future needs and changing technologies.

Born in Shanghai in 1934, Liu and his family relocated to Taiwan during the Chinese Civil War. After earning his bachelor's degree in electrical engineering from National Taiwan University in 1954, he and his family moved to the United States. Liu and his father pursued master's degrees in electrical engineering at the Polytechnic Institute of Brooklyn (now New York University Tandon School of Engineering) in 1956.

He subsequently earned his doctoral degree in electrical engineering from the same institution four years later.

In 1959, Liu received a prestigious Bell Labs fellowship and worked at the company's Murray Hill, New Jersey location until he joined Princeton in 1962. His collaboration with former graduate student Abe Peled led to the publication of the influential 1976 textbook, "Digital Signal Processing: Theory, Design, and Implementation," which became a standard reference for engineers worldwide.

Liu authored 250 technical papers and received 12 U.S. patents for his groundbreaking work, including one in 1976 for a hardware design that processed bits in parallel, significantly increasing computing efficiency for data including sound and communication signals.

Liu's influence extended beyond his own research, as he mentored 53 doctoral students, many of whom achieved distinguished careers in academia and industry, including leadership positions at Google and IBM. Notably, former student Robert Kahn, co-creator of the modern Internet architecture, received the 2024 IEEE Medal of Honor.

During the 2000s, Liu shifted his focus to media integrity and copyright issues. In his 2002 book, "Multimedia Data Hiding," co-authored with former doctoral student Min Wu, Liu discussed the theory, techniques, applications, and security of digital watermarking. This innovation helps identify genuine copies of songs, images, or videos, preventing unauthorized alterations and protecting intellectual property rights.