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A high efficiency and contrast enhanced halftoning is presented in this paper. The contrast of digital image highly depends on the nature of the ambient lighting and the quality of the lens. The required processing time skyrockets when a high resolution and quality printed work is needed. In this paper, we employ the benefits of high speed ordered dithering and high quality error diffusion to simultaneously solve the problems we described above. As the experimental results demonstrate, this technique is able to enlarge the dynamic range of the histogram and improve execution efficiency to around 15%~47% with the tested images

In this paper, we propose a novel technique for embedding flexible amounts of data into a dithering halftone image and still achieving a high quality result. In the encoder, we reserve the high frequency regions with nearly the same number of black and white pixels by calculating the pixel connection. The secret data is embedded into these regions. In the decoder, a blind decoding technique is applied without prior knowledge of the original dithering image but with some side information. From the experimental results, a subjective high quality image with flexible capacity is obtained. Moreover, the correct decoding rate is kept 100%, and the original dithered halftone image can also be reconstructed in the receiver

In this paper, we propose a new technique for converting gray level images into bi-level images, while the most significant information in original gray level image are preserved. From experimental, the reconstructed quality is better than Otsu and Kapur's methods. The well-known digital halftoning is traditionally applied to get a high quality binary image for specified output devices, e.g., printers. However, the halftone image is not suitable for some image processing, such as downsampling or further compression. These problems can be solved with the proposed 3-step bi-leveling, which including Sobel high active regions detection, LMS-designed halftoning, local and global smooth region binarization