Abstract: Existing image enhancement algorithms by using of Discrete Cosine Transform mostly treat the DCT coefficients uniformly, and can not inhibit artifacts. By introducing Retinex idea into DCT, a new enhancement algorithm is proposed. The algorithm divides DCT coefficients into illumination component and reflection component. The dynamic range of illumination component is mapped to an ideal range, using a function with strong light bating. The local details of reflection component are enhanced by defining a band limited contrast measure. The block artifacts will be suppressed using a block decomposing method. Compared to MSR and DCT enhancement algorithms, results verify this approach’s efficiency of details enhancement and strong light bating, also with artifacts suppressed.

Key words: computer application, image enhancement, discrete cosine transform, Retinex