Recently, several algorithms have been developed to hide data in either text images or halftone images. According to an observation that the number of transitions between black pixel and white pixel in the halftone image is much larger than that in the text image, this paper presents a unified min-max transition (MMT) scheme to embed data into the above two types of images without visual degrad...

The conventional method for sending halftone images via facsimile machines is inefficient. The previously proposed ToneFac algorithm improves the transmission of halftone images. ToneFac represents a halftone image by mean gray values of the disjoint blocks and an error image, which records the difference between the desired halftone and the halftone generated using the mean gray values. To imp...

Since digital right management of digital media data has received considerable attention recently, protection of halftone image documents becomes another important topic. Image-based visual cryptography is found to provide an alternative for applications of copyright protection by overlapping more than one secret embedded image to show the hidden information. In this paper, we propose a novel s...

Since digital right management of digital media data has received considerable attention recently, protection of halftone image documents becomes another important topic. Imagebased visual cryptography is found to provide an alternative for applications of copyright protection by overlapping more than one secret embedded image to show the hidden information. In this paper, we propose a novel sc...

A novel method is presented to manufacture multilevel diffractive optical elements (DOEs) in polymer by single-step KrF excimer laser ablation using a halftone mask. The DOEs have a typical pixel dimension of 5 μm and are up to 512 by 512 pixels in size. The DOEs presented are Fresnel lenses and Fourier computer generated holograms, calculated by means of a conventional iterative Fourier transf...

As digital halftone images are widely used in the printing of books, magazines, newspapers and computer printers, the ease with which perfect copies can be made, may lead to large-scale unauthorized copying. Watermarking has been considered for many copy prevention and copyright protection applications. The hybrid watermarking system is proposed for halftone images that the watermarks embedded ...

The reduction of a structural pattern at specific gray levels or at the special condition of image data has mainly been discussed in digital halftone methods. This problem is more severe in some flat panel displays because their black levels typically are brighter than other displays blocks. The authors proposed an advanced confined error diffusion (ACED) algorithm which was a well-organized ha...

A method of concealing an image in a different halftone image is proposed. Continuous-tone levels of the visible images are represented by the area of the halftone dots. However, the hidden image is encoded by the dots' positions inside their cells. Only a spatial correlator with a unique filter function can reveal the hidden image from the halftone picture. The technique and its robustness to ...

This paper presents a new digital watermarking algorithm for color halftone images. According to the Minimal Brightness Variation Quadruples (MBVQ), this paper gets the conclusion that each pixel of color halftone image belongs to one of the five MBVQs. Based on the edge and MBVQ, this algorithm implements the watermark embedding in the halftone process. Experimental results show that the algor...