Since its discovery in 1989, electroluminescence from conjugated polymers has been a field of intensive research. One particular advantage of polymers compared to their small molecule counterparts is their processability from solution. This makes them the ideal active layer to be used for flat panel displays because the different colors can be ink jetted economically even onto relatively large substrates. Ink jet technology for polymer light emitting diodes (PLEDs) and full color displays, however, is not yet an established display production technology. A detailed understanding of the underlying principles and the interaction of print head, ink and substrate is a prerequisite for the development of the technology. This paper presents performance data of ink jetted PLEDs and compares them with the respective spin coated devices. These devices have been prepared on a substrate with a simple, low resolution photo resist structure. As the target application is the manufacture of full color displays, the light emitting polymers investigated in this study were red, green and blue. The results show that a careful choice of the printing parameters and environment results in devices with current-voltage, brightness-voltage and emission characteristics comparable to spin coating samples, which have been prepared as reference. The film homogeneity of the functional layers turned out to be of utmost importance and can be influenced by various jetting parameters.

A large-scale investigation into the perception of contrast in color images was performed. Psychophysical experiments were performed to determine the influence of image lightness, chroma, and sharpness transforms on perceived image contrast and observer preference. The influence of these transforms on perceived contrast was investigated separately by independent soft copy, paired comparison tests of contrast perception and image preference. The perception of contrast across transformations was also investigated, as was the perception of image contrast relative to the most preferred image manipulation. In all, four experiments of contrast perception and image preference were performed by at least thirty-two observers each. Results of the lightness, chroma, and sharpness-contrast experiments indicate perceived image contrast is a function of multiple image characteristics as opposed to simply being a function of the dynamic range of image intensity. In the lightness-contrast experiments, images of identical white and black points were scaled to have significant differences in contrast based on their manipulations from the original image. In the chroma-contrast experiments, images of identical lightness channels were scaled to have significant differences in perceived contrast due to relative chroma amount. In the sharpness-contrast experiments, images of identical white and black points were scaled to have significantly different levels of perceived contrast due to sharpness. In the scale-linking experiment, it was found that images of the above manipulations could be scaled similarly for perceived contrast. All scales of perceived contrast and image preference were found to be image independent among pictorial images, regardless of observer experience.

Psychophysical experimentation was performed on the perceived contrast of color images and its effect on observer preference. Goals of this research included the following: investigation into the roles of image lightness, chroma and sharpness manipulations on perceived image contrast; modeling the perception of image contrast with physical image parameters; the relation of perceived contrast of an image to the most preferred version of that image; and the generation of a large scale image contrast data set for later use in image difference/quality metric development. These goals were undertaken by administration of soft copy paired-comparison experiments of perceived image contrast and observer preference. These tests were performed over four months, by more than seventy observers. Perceived image contrast was determined to be scalable with respect to lightness, chroma, and sharpness manipulations. Perceived image contrast scales were image independent between five pictorial images. Significant contrast differences between images of identical white and black points were perceived, demonstrating that image white and black points do not solely determine image contrast. Significant image contrast differences were found between full color images and their achromatic versions, thus demonstrating that perceived image contrast is a function of image chroma information. It was also shown that the perceived contrast of achromatic images is higher than perceived contrast of very low chroma images. Perceived image contrast was empirically modeled using physical parameters of the images. Values based on image lightness, chroma, and sharpness information were used to model the perception of image contrast in a relative and stand-alone sense. In Reproduction Versus Preferred (RVP) contrast modeling, image parameters were taken relative to the most preferred version of the image. In Single Image Perceived (SIP) contrast modeling, parameters of single images were fit to scales of perceived contrast. RVP contrast modeling illustrated that image contrast is perceived relative to the most preferred version of that image. SIP contrast analysis indicated differences in perceived contrast were perceived image independent, and reinforced perception of image contrast relative to the most preferred version of an image. This concept of contrast perception relative to the preferred image indicates image contrast can be described without knowledge of an original scene in the image capture sense or knowledge of an original image in the image reproduction sense.

This paper describes work carried out to predict the result of a psychophysical experiment in which observers made judgments about the types of differences they perceived between originals and reproductions rendered on different media. The results of these observer–reported visual data are compared with analogous metrics extracted from colorimetric data of the corresponding originals and reproductions. While there is good agreement in terms of the most general findings, looking at more detailed results shows significant differences between visual and colorimetrically–based information. The paper then introduces a colorimetrically based image difference metric that takes into account some aspects of the human visual system. Using information both about the statistics of color differences, of the original images and of changes to spatial characteristics, the metric is able to give a close prediction of observer responses. The final delta-ICM metric is proposed for further testing as a means of predicting observer responses of image difference in cross–media color image reproduction as well as other applications.

The equipment needed to take astronomical images of deep sky objects, those faint targets found only with optical assistance, is within the reach of dedicated amateur astronomers. In such low light levels there is no color, strictly, but there is a natural desire to make these images look as they might appear if our vision were sensitive enough to perceive color. This is a component of esthetic presentation, and the use of color for this subject is extremely useful in education. CCD imaging equipment allows us to record and measure the spectral energy in a specific band determined by a filter placed in front of the sensor. By making several such recordings through red, green, blue, and sometimes additional filters, a full color composite can be created. Of particular interest are emission nebulas, whose spectra comprise the lines of energized gases. These are present in a scene along with the broadband blackbody emissions of stars. Because the spectra of these objects are simple or well known, they can be modeled and their recordings calibrated. Conventional color science methods can then be used to generate colorimetrically correct renditions of the scene.

An algorithm which exploits binary data representation for efficiently interpolating lookup tables (LUTs) is developed. Some implementation cost and accuracy trade-offs among trilinear, tetrahedral and binary proportional interpolation (BPI) when constrained to no more than one LUT access per pixel are compared for color space conversion of digital images. A simpler sample dither implementation of BPI, called Neighborhood Mask Dither Interpolation (NMDI), is also described.