A method of providing a digital image with a unique, machine readable, code image is presented. It is called "Full Spectrum," because the method uses Fourier transform techniques to embed the code in a wide range of spatial frequencies. The changes made to the original image by the encoding process are meaningless to the observer, and, by proper choice of the embedding parameters and the resolution (reproduction size) of the marked image, they can be made imperceptible. Full Spectrum has some intrinsic advantages for application to printed security structures in a document authentication and identification environment. Using its mathematical properties, the method is shown to be invariant to shifting and robust to cropping, which enables the code image to be reconstructed from a recording of the document with arbitrary position and size. Techniques to deal with possible rotation and scaling of the recorded image with respect to the (printed) original are elaborated. Finally, a general method is developed to match the reconstructed code image to the reference image (expected code image). Experiments show that the code image can survive various graphical transfer processes, such as halftone screening, printing and digitizing. An actual document containing a printed Full Spectrum structure, the Security ID, is used as a practical example.

In this article a region based color image watermarking algorithm is presented. The objective of the method is to embed a particular message in each region of interest (ROI) in the image. The embedding message has to be detected after image manipulations such as cropping, rotation and color JPEG compression. As a basis for the watermarking, a segmentation algorithm is used. Based on the extracted regions, characteristic features are estimated by using shape information. The embedding message is synchronized with each ROI on each color component Y, Cr and Cb. To embed information non-rounded DCT coefficients are watermarked. Experimental results show the performance of the algorithm against spatial and frequential attacks.

This article presents a method to remove watermarks from watermarked spectral images. The watermarks were added through the Principal Component Analysis (PCA). The removal is also performed using the PCA transform. Experimental results indicate that the removal of the watermark can be performed successfully.

Recently, the wavelet transform has been widely applied in the watermarking research due to its excellent property of multi-resolution analysis. This article proposes an adaptive watermarking capacity analysis in the wavelet domain. This is different from most previous works that focused on spatial domain. This article discusses the relationship between the watermarking capacity and the watermark detection bit error rate (BER), and derives the relation between the capacity and the bounds of BER. Based on this research, the detection error rate of watermark is mainly influenced by the watermark average energy and the watermarking capacity. The error rate rises with the increase of watermarking capacity.

With the popularity of digital still cameras (DSCs), improvement of image quality in dark areas of the image is needed. There are two typical techniques for this: gamma correction and histogram equalization. However, such techniques are not always sufficient to improve scene detail in dark areas. Recently, examinations of Retinex theory taking into account the human vision model proposed by Land are being given attention. This algorithm, which utilizes spatial information between surrounding pixels, gives good image detail. Single-scale Retinex (SSR) and Multi-scale Retinex (MSR) are typical Retinex algorithms. However, they raise several practical use issues concerning color images reproduced by printers. In order to address such issues, Adaptive Multi-scale Retinex (AMSR) synthesis of images originally processed by MSR to the original image has been proposed. This algorithm consists of two processes, linear computation and synthesis of both the original image and the image processed by MSR. AMSR can be compared to histogram equalization and MSR for DSC images. AMSR shows that visibility in dark areas can be improved compared to other techniques. Moreover, NEW-AMSR has the following two features: suppression of chromatic unbalance in R, G and B channels, and a high speed processing technique to compute a weighted average.

A spectral classifier for pixels on the basis of measurements made with two or more broad, spectrally-overlapping sensitivity curves has been called Artificial Color, because animals appear to do the same thing. While Artificial Color appears very attractive in tests to date, it has the drawback of being pixel-by-pixel. We know there are neighborhood effects in the perceived color in animals. The purpose of this article is to introduce and study the effects of neighborhood operations in Artificial Color.

In this article we describe NVIZ, an interactive environment for system level investigation of neural function. NVIZ combines simulation, visualization and analysis in a single software system that encompasses five biological levels of organization, from ion channels to generated behavior. Once a simulation has been completed, cell-level output data can be visualized as height fields (presenting data from an entire population in a compact representation), or within an anatomical model of cat spinal cord. NVIZ provides a set of numerical analysis tools such as histograms, and a variety of 2D plots that permit both population and cell level analysis within the software system. Movement of a visualized limb segment is generated from activity of motoneurons, using a novel new algorithm called Net Neural Drive. The linked visualizations in NVIZ provide a powerful means to comprehend neuronal activity generated in complex models involving thousands of cells. The ability to design or modify neural circuits involving multiple populations, followed by simulation, visualization and analysis promotes rapid experimentation and the ability to digest massive amounts of time-varying simulation data. NVIZ is highly scalable, in terms of the number of populations, neurons, and limb segments. Using interactive tools, the visualization can be easily customized to focus on neural activity of interest. We demonstrate the application of NVIZ to understanding locomotion of a single limb joint, using a central pattern generator model.

A new method for measuring the dark conductivity of emulsion microcrystals using a microwave technique is described. The principle behind this method is the reduction of the resonant cavity 'quality factor' which occurs due to the electric power loss associated with the conductivity of microcrystals present in the cavity. Measured conductivity of both cubic and octahedral microcrystals was greater for smaller sized crystals of either habit. For crystals of the same size, conductivity was greater for the octahedral crystals. These results coincide well with reported ionic conductivity measurements of silver halide microcrystals. However, the values obtained by the proposed method differ from those obtained elsewhere with the conventional dielectric loss method. In this new method, unlike in the dielectric loss method, crystal shape does not influence the measurement.

The potential profile in the space charge layer with excess negative kink sites on the surface and corresponding interstitial silver ions in the interior of silver halide influences the distribution of latent image centers in it, depending on the presence of photographic stabilizers and antifoggants on its surface. In this article, the effect of the space charge layer on the spectral sensitization is explained from the following viewpoint. The electronic energy levels of a sensitizing dye molecule are higher on a negatively charged site than on a neutral site. An exciton, i.e., an excited dye molecule in a J-aggregate, migrates and injects an electron to the conduction band of silver halide more rapidly and efficiently on a negatively charged site than on a neutral site. A positive hole migrates in a J-aggregate and is kept by a dye molecule on a negatively charged site for longer time than by a dye molecule on a neutral site. It is known that the concentration of negatively charged sites is larger on octahedral grains than on cubic ones. It is then demonstrated that the above-stated viewpoints and knowledge explain the spectral sensitization phenomena. Namely, the quantum yield and rate of the electron injection by excited dye molecules for spectral sensitization are larger on octahedral grains than on cubic ones. The decay time and concentration of positive holes in J-aggregates, which are responsible for the dye desensitization, are larger on octahedral grains than on cubic ones.