Color printing proceeds with multiple halftone separations overlay. Because of separation overlay misalignment in printing, the percentage of different primary color combination may vary and it will result in color shift. In traditional printing procedure with AM halftone, every separation has different screening angle to make the superposition pattern in a random style, which will reduce the c...

We describe computational experiments to predict the perceived quality of multi-level halftone images. Our cornputations were based on a spatial color difference metric, S-CIELAB, that is an extension of CIELAB, a widely used industry standard. CIELAB predicts the discriminability of large uniform color patches. S-CIELAB includes a pre-processing stage that accounts for certain aspects of the s...

In this paper, we propose a novel way called DHCED to hide invisible patterns in two or more visually different halftone images (e.g. Lena and Harbor) such that the hidden patterns would appear on the halftone images when they are overlaid. Conjugate Error Diffusion is used to embed the binary visual pattern in the two distinct halftone images. Simulation results show that the two halftone imag...

The efficient encoding and transmission of information for facsimile communication relies on redundancy in the scanned pixels. Halftone images, especiaily those rendered by high-quality dispersed dot techniques, are "busy" with alternative black and white pixels and shorter run lengths as compared to text information. Because of this, it is desirable to increase the redundancy and decrease the ...

In this paper, we propose a novel method called DHSED to hide binary visual patterns in two error diffused halftone images. While one halftone image is only a regular error diffused image, stochastic error diffusion is applied to the other image to generate special stochastic characteristics with respect to the first image such that the visual pattern would appear when the two halftone images a...

A new feature extraction method based on multidirectional correlation function is proposed for improving the classification performance of halftone images in this paper. The correlation function is improved to obtain feature vectors on three directions of halftone images. Based on the definition of pixel probability, pixel entropy and entropy histogram, we introduce a decision rule to reject so...

Modulating the orientation of elliptically clustered dots in each halftone cell enables binary data to be embedded into the clustered halftone dots. In this paper, a new decoding method is proposed for recovering hidden binary data from clustered halftone dots by using learned dictionaries, which are optimized to represent clustered dots with different elliptical shapes. The basic idea is that ...

Error Diffusion has been widely adopted in the printing industry due to its good visual quality and simple implementation. However, error diffusion still possesses its own deficiencies. Thus multiscale error diffusion (MED) has been developed, and this method outperforms traditional error diffusion according to extensive research results. The majority of previous halftone image watermarking tec...

Spatial frequency separability is proposed as an attractive exploit for obtaining color halftone watermarking methods from monochrome clustered-dot halftone watermarking techniques. Detection of watermarks embedded in individual halftone channels is typically confounded by the cross-coupling between colorant halftone separations and scan RGB channels caused by the so-called “unwanted absorption...

This paper proposes a reversible data hiding method for error diffused halftone images. It employs statistics feature of pixel block patterns to embed data, and utilizes the HVS characteristics to reduce the introduced visual distortion. The watermarked halftone image can be perfectly recovered if it is intact, only a secret key is required. The method is suitable for the applications where the...