Discrete cosine transform-based image coding and decoding method

Details Discrete cosine transform-based image coding and decoding method Discrete cosine transform-based image coding and decoding method

1994-02-09

1995-06-20

Chin, Stephen

Pulse or digital communications

Bandwidth reduction or expansion

Pulse code modulation

348398, H04B 166

Patent

active

054266734

ABSTRACT:
A fast discrete cosine transform (DCT) based method of encoding and decoding signals is disclosed. A signal of finite length is decomposed into subsignals of shorter length and an approximate DCT (A-DCT) is computed by keeping only selected subsignals. Computation time decreases relative to the number of subsignals being used to compute the A-DCT, fewer subsignals resulting in a faster computation. For signal compression applications, the computed A-DCT coefficients are quantized and coded. For signal recovery, the encoded A-DCT coefficients are processed through a decoder and the decoded signal is recovered using a direct inverse DCT (I-DCT). In some applications, an approximate inverse DCT (AI-DCT) based on similar decomposition can be used to recover the signal from the encoded data. In image coding applications, the image recovered from the decoded signal exhibits negligible block artifacts compared to conventional JPEG, particularly for low bit rate compression.

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