Fast image enhancement in compressed wavelet domain

• We propose an efficient and flexible image enhancement framework.
• Brightness, contrast, sharpness, noisiness, and color consistency are considered for enhancement.
• Wavelet properties enable both global and local enhancement.
• The framework achieves computationally efficient for best wavelet encoded images since enhancement is performed in the wavelet domain.
• The experiments show that the proposed method achieves both visually and numerically good results to the existing approaches.

This paper presents computationally efficient framework for color image enhancement in the compressed wavelet domain. The proposed approach is capable of enhancing both global and local contrast and brightness as well as preserving color consistency. The framework does not require inverse transform for image enhancement since linear scale factors are directly applied to both scaling and wavelet coefficients in the compressed domain, which results in high computational efficiency. Also contaminated noise in the image can be efficiently reduced by introducing wavelet shrinkage terms adaptively in different scales. The proposed method is able to enhance a wavelet-coded image computationally efficiently with high image quality and less noise or other artifacts. The experimental results show that the proposed method produces encouraging results both visually and numerically compared to some existing approaches.