The Hong Kong Chapter of IEEE Signal Processing Society (SPS) organized the 4^th Signal Processing Postgraduate Forum on Saturday, April 24 2010 at the Chinese University of Hong Kong.  Every two years, the SPS Hong Kong Chapter organizes the Forum as an opportunity for the local signal processing research students to get together and discuss their research. The Forum considers topics listed under the ICASSP and ISCAS conferences.  Each presentation represents an original work done by a postgraduate student or a research assistant  supervised by an academic staff member at one of the eight universities in Hong Kong. Each presentation is associated with a paper that has been recently published or accepted for publication in international conferences or journals. For several years in a row, the Forum has been successfully held together with a SPS Distinguished Lecture.  Prof. Charles Bouman of Purdue University delivered the Distinguished Lecture on "Model Based Imaging: In Search of the Free Lunch" with this year's Forum. The detailed program schedule can be found at the Forum website. (Information provided by Dr. Brian Kan-Wing Mak, Chapter Chair of the SPS Hong Kong Chapter)