Imbibition and evaporation of picoliter (pL) sized water droplets on paper media commonly used for inkjet printing is measured using high speed imaging system. Three types of uncoated and coated paper samples were chosen: multipurpose uncoated paper (80 g/m²), matte coated paper (230 g/m², and gloss coated paper (240 g/m². As a reference, the rate of the evaporation process was quantified by using three impermeable solid substrates with different wetting characteristics, i.e., silicon, glass, and hydrophobized glass. It is shown that for water droplets of about 60 pL, imbibition is the dominant phenomenon on the matte and gloss coated paper leading to a total drying time (imbibition plus evaporation) of 10–15 ms for gloss coated paper and 30–150 ms on the matte coated paper. In the latter sample, different regimes in the imbibition process were correlated with the layered structure of the sample. The drying process on the multipurpose paper is dominated by evaporation, with initial drying rate of 0.4–0.6 pL/ms.

We present a new experimental method to assess the jetting performance of fluids for use in drop-on-demand (DoD) ink jet printheads. The oblique collision of two continuous liquid jets leads to the formation of a thin oval liquid sheet bounded by a thicker rim which disintegrates into ligaments and droplets. Under certain conditions the flow structure exhibits a remarkably symmetrical "fishbone" pattern composed of a regular succession of longitudinal ligaments and droplets. For a series of model elastic fluids containing polystyrene (PS) in diethyl phthalate (DEP), and also for solutions of polyethylene oxide (PEO) in glycerol/water, ejected from nozzles with an internal diameter of 0.85 mm, the shape of the fishbone pattern varies strongly with polymer concentration. The same fluids were also used in a Xaar piezoelectric DoD print head to characterize their jetting performance in terms of the maximum ligament length, a crucial parameter in determining the printability of the fluid. There are close similarities between the ligament collapse behaviors in both experiments. Good correlation was found between the maximum included angle of the fishbone pattern and the maximum ligament length in the jetting experiments, which suggests that a test based on oblique impinging jets may be useful in the development of fluids for ink jet printing.

In the present article we analyze the relationship between ambient illuminations and psychological effects while viewing still images displayed on a liquid crystal display (LCD). In two experiments, six kinds of images were displayed on the LCD under different brightness of illumination conditions and were rated by 15 observers, and four kinds of images were displayed under different colors of illumination conditions and were rated by 27 observers. The semantic differential method and factor analysis method are introduced to analyze the subjective evaluation. It is shown that comfort in viewing is enhanced according to the increase in brightness of the ambient illumination. Particularly, realistic sensation and dynamism are enhanced while retaining comfort with the illumination behind the LCD. It is also shown that realistic sensation and dynamism and comfort are enhanced under the illumination of average chromaticity of displayed images.

In this research, we develop a practical lighting reproduction technique to reproduce the appearance of a face under an arbitrary lighting condition in a facial live video with rigid facial motion. The reproduced facial image has texture detail and novel shading by combining image-based components and model-based components. Our technique is practical because it requires using only polarizing filters with the conventional green screen matting technique.

The images captured by most current digital cameras suffer from a narrow dynamic range that results in poor color fidelity and perceived image quality. Accordingly, this article proposes an enhanced integrated multi-scale Retinex (IMSR) method in a device-independent color space, namely, CIELAB, to preserve the hue and obtain a high contrast and naturalness. To achieve the desired objectives, a captured sRGB image is transformed into CIELAB color space using standard equations, then the IMSR is applied to only the L^* values, thereby preserving the balance of the color components, hue, and saturation. However, since this process causes unnatural undersaturation, a saturation adjustment is performed by applying a simple saturation compensation method, which maintains the chromatic ratio with respect to the sRGB gamut boundary according to the variation in the luminance. The adjusted CIELAB values are then transformed into sRGB using an inverse transform function. In experiments, the proposed method showed an improved visibility in both dark and bright regions, while reducing color distortion. Furthermore, in an observation preference test, the images resulting from the proposed method were perceived as having a higher visibility and naturalness.

A method of converting cyan, magenta, yellow, and black (CMYK) digital values into cyan, magenta, yellow, black, light cyan, and light magenta (CMYKLcLm) in six-color printers is proposed for providing a better print quality with less dot visibility, high color fidelity, and smooth color transition. Based on the attribute of the dependent variable Lm and Lc to M and C, the input M and C digital values are separated into MYLm and CLcLm digital values, respectively, according to three types of region: bright, middle, and dark. In bright regions, the input M digital values are separated into LmY digital values minimizing the colorimetric errors to compensate for the hue difference between M and Lm, while C is separated into LcLm in the same manner. In middle regions, to guarantee a gradual lightness transition between bright and dark regions, M and C are newly included along with LmY and LcLm used in bright regions, respectively, which raises a redundancy problem, i.e., many to one mapping between M and MYLm or C and CLcLm. To solve this problem, a digital-patch-based dot visibility metric, which avoids the need to scan a large number of printed patches, is proposed based on the standard deviation of the lightness component for digitally bilevel patches through model-based error diffusion, thereby making it possible to choose the unique MYLm and CLcLm with the lowest dot visibility score. Finally, in dark regions, the input M and C digital values are modified by the M and C with the closest color to reduce the use of unnecessary amounts of colorant. Moreover, to eliminate the appearance of color tones on the gray ramp, the input gray CMY digital values are converted into CMYK digital values using a simple gray component replacement, and the input CMY digital values in the predefined gray boundary regions are then transformed by a weighted sum of the CMYLcLm obtained from above-mentioned color separation and the separated CMYK on the gray axis. Experimental results show that the proposed method is able to produce printed images with both a lower color difference and a lower dot visibility when compared to conventional methods.

In this paper, a new method for efficient generation of video hologram for three-dimensional (3D) video is proposed by combined use of redundant data of 3D video and look-up table techniques. That is, 3D video is a collection of sequential 3D images having depth data as well as intensity and neighboring moving pictures in the 3D video differ slightly from each other. Therefore, a method for fast computation of computer generated holography (CGH) patterns for 3D video images is proposed by combined use of temporal redundancy and look-up table techniques. Furthermore, adjacent pixels of a 3D image have very similar values of intensity and depth, and some of them even have exactly the same values of them. In other words, a 3D image has a spatial redundancy in intensity and depth data. Therefore, a method for fast computation of CGH patterns for the 3D image taking into account of the spatial redundancy of the 3D image is proposed. To confirm the feasibility of the proposed method, some experiments with a 3D test object are carried out and the results are compared to those of the conventional methods in terms of a computational speed and a required memory size.

Passive autofocus (AF) is a key component of many digital and high megapixel smart-phone camera systems. In order to make informed choices in the selection of a passive AF search algorithm, it is essential to utilize sound performance metrics. The performance metrics currently employed do not take into account all facets involved in passive AF systems. In this article, five performance metrics are proposed to be simultaneously evaluated in order to accurately reflect all aspects of a passive AF system including focusing speed, accuracy, power consumption, and user experience. Experimental results on a prototype digital camera platform for four representative AF search algorithms are presented to show how to carry out the evaluation of any passive AF search algorithm.

An algorithm for image segmentation of the secondary septa in the lungs using light microscopy is presented. After converting the original analog image to binary with proper thresholding, morphological operations are applied to individual lumen regions to extract the secondary septum regions that appear as cavelike regions in each lumen. To reduce the errors of misclassifying the primary septa from secondary septa because of the occasional leaks in the broken primary septum lines, a gap-closing procedure is designed before another separation procedure of the secondary septa is executed. The algorithm is applied to real lung images of both normal and cancerous lungs. The results show that the algorithm is robust and is able to identify and segment the secondary septa in lungs effectively.