Bede Liu, a digital signal processing pioneer, has died

Bede Liu, a digital awesome processing pioneer, died connected 7 May. He was 91.

Liu was wide regarded arsenic 1 of the founders of modern integer signal processing, a section that applies mathematical algorithms to analyze, modify, and transmit signals including sound, images, and video.

The IEEE Life Fellow taught electrical engineering astatine Princeton for much than 50 years. From 1994 to 1997, he chaired the university’s electrical and machine engineering department.

Liu’s investigation aided the modulation from analog to integer processing of sound, images, and video. His activity helped found galore of the mathematical and engineering techniques that underpin modern communications, multimedia systems, and consumer electronics.

Although small known extracurricular engineering circles, his activity is embedded successful technologies utilized by billions of people. The low-power integer awesome processors that make cellphone calls, streaming video, and Internet communications imaginable tin beryllium traced to investigation he conducted successful the 1970s and ‘80s.

Liu received the 2018 IEEE Jack S. Kilby Signal Processing Medal for “sustained contributions to the study and the improvement of low-complexity realizations of integer awesome processing algorithms.”

“We watercourse euphony and video. We return photos pinch our phones, and we nonstop them around. We don’t moreover deliberation astir it,” IEEE Life Fellow H. Vincent Poor said successful an obituary for Liu. “But it’s each because of the awesome processing, image processing, and video processing that’s been developed complete the years, arsenic good arsenic different technologies that person grown up beside it and enabled it, for illustration semiconductors. The improvement of these processing advances was precisely what Bede was a awesome portion of.” Poor is simply a professor of electrical and computer engineering astatine Princeton.

An impactful clever clever and teacher

Liu was calved successful Shanghai successful 1934. During his childhood, his family relocated to Taiwan amid the upheaval of the Chinese Civil War. His father, Henry Liu Sr., was an electrical engineer.

Liu earned his bachelor’s grade successful electrical engineering successful 1954 from the National Taiwan University, successful Taipei. After graduating, he and his family moved to the United States. Liu and his begetter attended the Polytechnic Institute of Brooklyn (now the New York University Tandon School of Engineering) together. They earned their master’s degrees successful electrical engineering successful 1956. Liu continued his studies astatine the school, earning a doctoral grade successful electrical engineering 4 years later.

In 1959 he was awarded a Bell Labs fellowship and worked astatine the company’s Murray Hill, N.J., location until he joined Princeton successful 1962.

“Liu was a highly impactful clever clever and teacher—always reasoning up of early needs and changing technologies,” said IEEE Life Fellow Peter J. Ramadge, a Princeton professor emeritus of engineering.

Cellphones make usage of a sizeable magnitude of integer awesome processing, Liu erstwhile noted. Many of the field’s advances, he added, progressive making blase processing applicable connected devices pinch constricted computing power—which is the situation that confronted generations of engineers designing portable electronics.

Liu’s investigation contributions helped style some the mentation and believe of integer awesome processing. With Abe Peled, a erstwhile postgraduate student, he authored the 1976 textbook Digital Signal Processing: Theory, Design, and Implementation, which is simply a modular reference for engineers. Published earlier integer awesome processing had afloat emerged arsenic a chopped discipline, it helped specify the taxable for practitioners and students astir the world.

Liu besides published 250 method papers and was granted 12 U.S. patents. His papers are disposable to publication connected the IEEE Xplore Digital Library.

The first patent granted to him and Peled was successful 1976 for a hardware creation that processed bits successful parallel, alternatively than successful sequence. The invention greatly accrued computing ratio for information including sound and connection signals.

Peled says Liu “demonstrated an openness to caller ideas and a willingness to situation the orthodoxy of the EE section astatine that time—which leaned heavy toward much theoretical accusation theory.”

A mentor to well-known engineers

Liu’s power extended beyond his ain research. He advised 53 doctoral students, galore of whom went connected to distinguished careers successful academia and industry, including activity positions astatine Google and IBM. One erstwhile student, machine intelligence Robert Kahn, helped create the architecture of the modern Internet. Kahn, an IEEE Life Fellow, received the 2024 IEEE Medal of Honor.

“His erstwhile students were very successful,” Poor said of Liu, “and I deliberation that’s a testament to his accomplishment arsenic a mentor.”

“Liu was a highly impactful clever clever and teacher—always reasoning up of early needs and changing technologies.”—Peter J. Ramadge

Together pinch respective Ph.D. students, Liu developed methods of filtering and compressing integer signals to mitigate errors and dramatically trim the computation needed for awesome processing.

As integer awesome processing moved from laboratories into commercialized products, the effect of Liu’s ideas dispersed crossed industries. His investigation helped spawn the improvement of lower-cost and lower-power electronics and contributed to advances successful mobile communications, multimedia technology, business automation, and biomedical imaging.

A attraction connected media integrity and copyrights

In the 2000s, Liu turned his attraction to media integrity and copyright issues.

“With the expanding accessibility of digital media root material, the protection of ownership and the prevention of unauthorized alteration has go an important concern,” he wrote successful his 2002 book, Multimedia Data Hiding. The book, which he co-wrote pinch his erstwhile doctoral student IEEE Fellow Min Wu, discussed the theory, techniques, applications, and information of integer watermarking—hidden signals that could place a genuine transcript of a song, image aliases video to forestall unauthorized distribution aliases tampering.

A Princeton squad that included Liu, Wu, and different of his doctoral students uncovered superior vulnerabilities successful watermarking technologies being considered by an manufacture consortium. They recovered that the standardization efforts were immature and would not protect against integer piracy.

“Now astir each transcript of a Hollywood movie fixed to a professional aliases theatre carries a unsocial integer forensic watermark to forestall unauthorized redistribution,” said Wu.

A unit successful the community

Liu, an progressive IEEE volunteer, served connected the IEEE Board of Directors successful 1984 and 1985. He was the 1982 president of the IEEE Circuits and Systems Society.

He was a personnel of the U.S. National Academy of Engineering, an academician of China’s Academia Sinica, and a overseas personnel of the Chinese Academy of Sciences.

Outside the classroom, he was recognized for his humility, humor, enthusiasm, and generosity. When reasoning of Liu, IEEE Life Fellow Kenneth Steiglitz says, cheer is the first connection that comes to mind.

Liu was “always fresh pinch a affirmative remark, a speedy grin or, maybe, immoderate tips connected the correct measurement to navigator a duck,” says Steiglitz, professor emeritus of machine subject astatine Princeton.

Liu encouraged his students to return connected ambitious, unconventional projects, and he inspired students and colleagues pinch his adventurous spirit.