Red-green opponency in the long visual fibre photoreceptors of brushfoot butterflies (Nymphalidae)

In many butterflies, the ancestral trichromatic insect colour vision, based on UV-, blue- and green-sensitive photoreceptors, is extended with red-sensitive cells. Physiological evidence for red receptors has been missing in nymphalid butterflies, although some species can discriminate red hues well. In eight species from genera Archaeoprepona, Argynnis, Charaxes, Danaus, Melitaea, Morpho, Heliconius and Speyeria , we found a novel class of green-sensitive photoreceptors that have hyperpolarizing responses to stimulation with red light. These green-positive, red-negative (G+R–) cells are allocated to positions R1/2, normally occupied by UV and blue-sensitive cells. Spectral sensitivity, polarization sensitivity and temporal dynamics suggest that the red opponent units (R–) are the basal photoreceptors R9, interacting with R1/2 in the same ommatidia via direct inhibitory synapses. We found the G+R– cells exclusively in butterflies with red-shining ommatidia, which contain longitudinal screening pigments. The implementation of the red colour channel with R9 is different from pierid and papilionid butterflies, where cells R5–8 are the red receptors. The nymphalid red-green opponent channel and the potential for tetrachromacy seem to have been switched on several times during evolution, balancing between the cost of neural processing and the value of extended colour information.

DEVELOPMENT OF A COLOURIMETRIC METHOD FOR QUALITY CONTROL OF SAUSAGE PRODUCTS PRODUCED USING CHITINOUS FOOD ADDITIVES

A crucial technological task that must be solved in the production of sausage products is to stabilize the product’s red colour. In this paper, we propose a scheme to determine the most significant parameters of the quality of dry-cured sausages by their colour characteristics. For this purpose, colour digital images were obtained, which were further processed using two classical colour representation systems: RGB and xyY. We monitored changes in pH and the ratio of water to dry matter in meat products. These crucial sausage properties were changed by introducing chitin-containing supplements into their recipes, which allowed us to solve two tasks simultaneously. The first comprises, as already mentioned, changing the properties of sausages to obtain correlations with colour characteristics. The second is to enrich meat products with chitin complex for preventive purposes to improve people’s nutrition. The construction of correlation dependencies using each coordinate separately in two colour systems showed that each system (RGB and xyY) has one colour channel with a maximum correlation coefficient. This is due to the colour features of sausages, which can be represented to the greatest extent with the help of only one colour coordinate in the considered colour representation systems (RGB and xyY). Using these colour coordinates will allow one to achieve maximum measurement accuracy. Thus, two tasks are being solved: the enrichment of food with dietary supplement and the development of a method to control their content.

Real-Time Haze Removal Using Normalised Pixel-Wise Dark-Channel Prior and Robust Atmospheric-Light Estimation

This study proposes real-time haze removal from a single image using normalised pixel-wise dark-channel prior (DCP). DCP assumes that at least one RGB colour channel within most local patches in a haze-free image has a low-intensity value. Since the spatial resolution of the transmission map depends on the patch size and it loses the detailed structure with large patch sizes, original work refines the transmission map using an image-matting technique. However, it requires high computational cost and is not adequate for real-time application. To solve these problems, we use normalised pixel-wise haze estimation without losing the detailed structure of the transmission map. This study also proposes robust atmospheric-light estimation using a coarse-to-fine search strategy and down-sampled haze estimation for acceleration. Experiments with actual and simulated haze images showed that the proposed method achieves real-time results of visually and quantitatively acceptable quality compared with other conventional methods of haze removal.

Developing a visual method to characterize displays

The goal is to develop a display characterization model to include the personal vision characteristics. A two-step model for visually characterizing displays was developed. It was based on the concept of half-toning technique for obtaining gamma factor for each colour channel, and unique hue concept for achieving 3x3 matrix coefficients, respectively. The variation can be presented by the optimized RGB primaries for each observer. The typical difference between the individual and the measured ground truth is 2.2 in terms of CIEDE2000 units.

FLAT VERSUS HEMISPHERICAL DOME PORTS IN UNDERWATER PHOTOGRAMMETRY

Underwater photogrammetry, like its counterpart in 'air', has gained an increasing diffusion thanks to the availability of easy-to-use, fast and often quite inexpensive software applications. Moreover, underwater equipment that allows the use of digital cameras normally designed to work in air also in water are largely available. However, for assuring accurate and reliable 3D modelling results a profound knowledge of the employed devices as well as physical and geometric principle is even more crucial than in air. This study aims to take a step forward in understanding the effect of underwater ports in front of the photographic lens. In particular, the effect of dome or flat ports on image quality in 3D modelling applications is investigated. Experiments conducted in a semi submerged indust rial structure show that the tested flat port performs worse than the dome, providing higher image residuals and lower precision and accuracy in object space. A significant different quality per colour channel is also observed and its influence on achievable processing results is discussed.

Using Watermarking Techniques to Prove Rightful Ownership of Web Images

This article introduces intelligent watermarking scheme to protect Web images from attackers who try to counterfeit the copyright to damage the rightful ownership. Using secret signs and logos that are embedded within the digital images, the technique can investigate technically the ownership claim. Also, the nature of each individual image is taken into consideration which gives more reliable results. The colour channel used was chosen depending on the value of its standard deviation to compromise between robustness and invisibility of the watermarks. Several types of test images, logos, attacks and evaluation metrics were used to examine the performance of the techniques used. Subjective and objective tests were used to check visually and mathematically the solidity and weakness of the used scheme.