FPGA implementation of pipelined 2D-DCT and quantization architecture for JPEG image compression

Abstract

Two dimensional DCT takes important role in JPEG image compression. Architecture and VHDL design of 2-D DCT, combined with quantization and zig-zag arrangement, is described in this paper. The architecture is used in JPEG image compression. DCT calculation used in this paper is made using scaled DCT. The output of DCT module needs to be multiplied with post-scaler value to get the real DCT coefficients. Post-scaling process is done together with quantization process. 2-D DCT is computed by combining two 1-D DCT that connected by a transpose buffer. This design aimed to be implemented in cheap Spartan-3E XC3S500 FPGA. The 2-D DCT architecture uses 3174 gates, 1145 Slices, 21 I/O pins, and 11 multipliers of one Xilinx Spartan-3E XC3S500E FPGA and reaches an operating frequency of 84.81 MHz. One input block with 8×8 elements of 8 bits each is processed in 2470 ns and pipeline latency is 123 clock cycles.