Halftone Visual Cryptography Embedding a Natural Grayscale Image Based on Error Diffusion Technique

Contrast-enhancing and deterministic tone mapping method in natural image hiding scheme using halftone images

“…We can visually confirm that the image quality is almost the same as [9] but sometimes visual artifacts appear that are derived from a error diffusion halftoning technique [12]. If there is a demand for users to create images again and again using dialog-based software, the halftoning method [11] is recommended due to the fast processing, but if the users notice any artifact, the halftonning method [9] may be more appropriate. Processing time increases in proportion to the number of image pixels.…”

“…If we use the fast halftoning method [11], the entire processing time is less than 1 second. The examples of output halftone images generated by method [11] are shown in Figure 11. We can visually confirm that the image quality is almost the same as [9] but sometimes visual artifacts appear that are derived from a error diffusion halftoning technique [12].…”

“…Two of them [9][11] generate high quality output halftone images. It takes about 130 seconds using the method [9] while it takes 0.40 seconds using the method [11] to generate output halftone images. If we use the fast halftoning method [11], the entire processing time is less than 1 second.…”

“…It takes about 130 seconds using the method [9] while it takes 0.40 seconds using the method [11] to generate output halftone images. If we use the fast halftoning method [11], the entire processing time is less than 1 second. The examples of output halftone images generated by method [11] are shown in Figure 11.…”

“…Thus, fast processing is realized because the proposed deterministic tone mapping requires no heuristic iterations. Any halftoning methods for natural image hiding [9][10] [11] can be used to generate output halftone images B X , B Y and B Z from proposed tone mapped images X, Y and Z. Two of them [9][11] generate high quality output halftone images.…”