Subjective reactions to misconvergence on a colour display

Subjective ratings of various degrees of misconvergence were obtained from subjects viewing text and graphics pictures on a 355 mm high-resolution shadow mask colour CRT display. The pictures were displayed in four secondary colours: white, yellow, turquoise (cyan), and pink (magenta). In commercial applications, user acceptance and satisfaction often present more stringent requirements for front-of-screen quality than do objective performance criteria such as legibility. In this case, it is expected that the picture quality would become unacceptable at lower levels of misconvergence than would cause it to be considered illegible. The results show a marked degradation in apparent quality of convergence as misconvergence increases from about 0.2 mm to about 0.5 mm. To obtain subjectively acceptable picture quality, misconvergence should be no more than about 0.3 mm and should be better than 0.2 mm over the majority of the screen. (The spot size of the display used was about 0.8 mm.) Textual and graphical pictures did not produce significantly different results.     

The Management of Water Colour in Peatland Catchments

The problems of water-colour management in peatland catchments are discussed. Colour may be managed in three areas of the reservoir catchment system: on the catchment itself, in the channel/conduit system and within the reservoir. Whilst a number of workers have considered the management of catchment areas and some have evolved tributary turnout strategies, no previous research has considered the role of the reservoir in the amelioration or enhancement of water colour. The management of water colour at Thornton Moor catchment (near Bradford) is described. In this catchment a staged approach has been adopted, with colour being managed in an integrated manner at three stages along the catchment/conduit/reservoir system.     

提高真丝印花绸色牢度的工艺研究

针对真丝印花绸普遍存在的水洗牢度差问题进行了研究探讨。通过实践,采用单宁—吐酒石法对真丝印花绸进行固色,提高了真丝印花绸的水洗牢度,并提出了在提高真丝印花绸色牢度方面需要注意的几个问题。     

Framestore system for map displays

The map displays project was undertaken to investigate techniques for the storage and display of geographical maps and related information and to develop the hardware and software required for a complete working system. Initially most of the project was concerned with the design of graphics hardware to be interfaced to a DEC LSI-11/03 micro-computer which was the main supply of computing power for the project. The development of one of the pieces of specialized hardware, the framestore display, is described.     

Image reconstruction from acoustical holograms using microprocessors

An acoustic imaging system using holographic techniques is described. Insonification of the object is achieved using a phased array scanner. Image reconstruction uses Fourier Transformations to produce a 128 × 128 pixel TV display. The system has the ability to focus in the ‘near field’ of its transducer arrays and has a frame rate of approximately 0.3 Hz.     

散射参考光法制作真彩色全息图

本文提出了用散射参考光制作2D真彩色全息图的原理,按本原理制作的全息图比用散射物光法制作的图像清晰得多,并且使记录激光能量得到充分利用,特别适用于记录大幅面彩色全息图。     

Automated Measurement of Uniform Pink Areas in Bricks Employing Morphological Operators

After a previous investigation into the feasibility of using image processing in the quality control system at a brickworks, it was concluded that the methods used could be developed into a commercial real-time quality control system, which could result in considerable cost savings. Among the measurements automated were methods that allowed the approximate measurement of the area of uniform pink colour on the surface of the particular brick type considered. However, even though the measurement was reported to be "quite good considering the complexity of the problem", it has been found that it could be enhanced and simplified by employing morphological operators. It is concluded that the method shows itself to be very robust to variation of pink coloration in the bricks and allows accurate colour segmentation of the bricks.     

The colour of the Mediterranean Sea: Global versus regional bio-optical algorithms evaluation and implication for satellite chlorophyll estimates

In this paper, uncertainties in the retrieval of satellite surface chlorophyll concentrations in the Mediterranean Sea have been evaluated using both regional and global ocean colour algorithms. The rationale for this effort was to define the most suitable ocean colour algorithm for the reprocessing of the entire SeaWiFS archive over the Mediterranean region where standard algorithms were demonstrated to be inappropriate. Using a large dataset of coincident in situ chlorophyll and optical measurements, covering most of the trophic regimes of the basin, we validated two existing regional algorithms [Bricaud, A., E. Bosc, and D. Antoine, 2002. Algal biomass and sea surface temperature in the Mediterranean Basin — Intercomparison of data from various satellite sensors, and implications for primary production estimates. Remote Sensing of Environment, 81(2-3), 163-178.; D'Ortenzio, F., S. Marullo, M. Ragni, M. R. d'Alcala and R. Santoleri, 2002. Validation of empirical SeaWiFS algorithms for chlorophyll-alpha retrieval in the Mediterranean Sea — A case study for oligotrophic seas. Remote Sensing of Environment, 82(1), 79-94.] and the global algorithm OC4v4 used for standard NASA SeaWiFS products. The results of our analysis confirmed that the OC4v4 performs worse than the two existing regional algorithms. Nonetheless, these two regional algorithms do show uncertainties dependent on chlorophyll values. Then, we introduced a better tuned algorithm, the MedOC4. Using an independent set of in situ chlorophyll data, we quantified the uncertainties in SeaWiFS chlorophyll estimates using the existing and new regional algorithms. The results confirmed that MedOC4 is the best algorithm matching the requirement of unbiased satellite chlorophyll estimates and improving the percentage of the satellite uncertainty, and that the NASA standard chlorophyll products are affected by an uncertainty of the order of 100%. Moreover, the analysis suggests that the poor quality of the SeaWiFS chlorophyll in the Mediterranean is not due to the atmospheric correction term but to peculiarities in the optical properties of the water column. Finally the observed discrepancy between the global and the regional bio-optical algorithms has been discussed analysing the differences between the two in situ datasets used for tuning the algorithms (SeaBASS versus ours). The main results are that methodological differences in the two datasets cannot play a major role and the inherent bio-optical properties of the basin can explain the observed discrepancy. In particular the oligotrophic water of the Mediterranean Sea is less blue (30%) and greener (15%) than the global ocean.     

Full Wave Modelling of Light Propagation and Reflection

The propagation and reflection of electromagnetic waves in a three‐dimensional environment is simulated, and realistic images are produced using the resulting light distributions and reflectance functions. A finite difference time domain method is employed to advance the electric and magnetic fields in a scene. Surfaces containing wavelength scaled structures are created, the interaction of the electromagnetic waves with these nano‐structured materials is calculated, and the sub‐surface interference and diffraction effects are modelled. The result is a reflectance function with wavelength composition and spatial distribution properties that could not have been predicted using classic computer graphic ray tracing approaches. The techniques are employed to reproduce demonstrations of simple interference and diffraction effects, and to create computer‐generated pictures of a Morpho butterfly.     

A zonohedral approach to optimal colours

This article demonstrates that the CIE XYZ colour solid is a zonoid. An approximating zonohedral colour solid is constructed explicitly from a set of generating vectors, which are integrals of colour‐matching functions over narrow intervals of the visible spectrum. The zonohedral approach yields an intuitive, constructive proof of the Optimal Colour Theorem: the reflectance function of an optimal colour takes on only the values 0 or 1, with at most two transition wavelengths. In addition, zonohedral techniques can simplify computations: for example, optimal colours can be found without calculating transition wavelengths. Finally, zonohedra provide a simple, unified approach to colour space and eliminate much of the confusion arising from chromaticity diagrams. © 2011 Wiley Periodicals, Inc. Col Res Appl, 2013