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The Integer Cosine Transform (ICT) presents a performance close to Discrete Cosine Transform (DCT) with a reduced computational complexity. The ICT kernel is integer-based, so computation only requires adding and shifting operations. This work presents a parallel-pipelined architecture of an 8×8 forward two-dimensional (2-D) ICT(10,9,6,2,3,1) processor for image encoding. A fully pipelined row-column decomposition method based on two one-dimensional (1-D) ICTs and a transpose buffer based on D-type flip-flops is used. The main characteristics of 1-D ICT architecture are high throughput, parallel processing, reduced internal storage, and 100% efficiency in computational elements. The arithmetic units are distributed and are made up of adders/subtractors operating at half the frequency of the input data rate. In this transform, the truncation and rounding errors are only introduced at the final normalization stage. The normalization coefficient word length of 18-bit (13-bit effective) has been established using the requirements of IEEE standard 1180-1990 as a reference. The processor has been implemented using standard cell design methodology in 0.35-μm CMOS technology, measures 9.3 mm2, and contains 12.4 k gates. The maximum frequency is 300 MHz with a latency of 214 cycles (260 cycles with normalization).
Date of Publication: Feb 2005