To deal with the ‘graying out’, ‘noise enlargement’ and ‘halo’ effects existing in classical Retinex image enhancement algorithms, an adaptive single scale Retinex scheme based on luminance is proposed. The edge information is incorporated into the Gaussian filter to restrain ‘halo’ and ‘noise enlargement’ effects, in which the filtering is carried out with adjacent pixels possessing the same characteristics. The original luminance is added to the obtained reflectance to restrain ‘graying out’ and ‘noise enlargement’ effects. Compared with other algorithms, the simulation results indicate that the proposed adaptive single scale Retinex scheme based on luminance can acquire more details, less ‘halo’, less noise and better color fidelity.