Visual signal evolution along complementary color axes in four bird lineages

ABSTRACTAvian color patterns function in varied behavioral contexts, most being produced by only a handful of mechanisms including feather nanostructures and pigments. Within a clade, colors may not occupy the entire available space, and incorporating complementary colors may increase the contrast and efficacy of visual signals. Here, we describe plumage patterns in four ecologically and phylogenetically diverse bird families to test whether they possess complementary colors. We present evidence that plumage colors in each clade cluster along a line in tetrachromatic color space. Additionally, we present evidence that in three of these clades, this line contains colors on opposite sides of a line passing through the achromatic point (putatively complementary colors, presenting higher chromatic contrast). Finally, interspecific color variation over at least some regions of the body is not constrained by phylogenetic relatedness. By describing plumage patterns in four diverse lineages, we add to the growing body of literature suggesting that the diversity of bird visual signals is constrained. Further, we tentatively hypothesize that in at least some clades possessing bright colors, species-specific plumage patterns may evolve by swapping the distributions of a complementary color pair. Further research on other bird clades may help confirm whether these patterns are general across bird families.

Complementary Color Barcode-Based Optical Camera Communications

Electronic displays and cameras can provide an intuitive, simple communications interface without dependence on additional wireless interfaces or the Internet infrastructure. In this paper, we design a complementary color barcode-based optical camera communication (CCB-OCC) system to provide an easy-to-use communication capability from an electronic display-to-camera (D2C) link. The proposed method encodes information into specially designed color barcodes and transmits it in a format perceptually invisible to humans but detectable by camera-equipped devices. In addition, we propose a new transmission packet design that contains pilot symbols to synchronize symbol packets and estimate the D2C channel link for calibrating captured images caused by irregular differences between the sending color and the receiving color in the D2C link. Experimental results verify the feasibility of the CCB-OCC scheme for short-range communications to offer additional information which shows a new possibility in designing a D2C communication system with robust to environmental change, easy-to-use, and simple implementation.

Using watermark visibility measurements to select an optimized pair of spot colors for use in a binary watermark

Spot colors are widely used in the food packaging industry. We wish to add a watermark signal within a spot color that is readable by a Point Of Sale (POS) barcode scanner which typically has red illumination. Some spot colors such as blue, black and green reflect very little red light and are difficult to modulate with a watermark at low visibility to a human observer. The visibility measurements that have been made with the Digimarc watermark enables the selection of a complementary color to the base color which can be detected by a POS barcode scanner but is imperceptible at normal viewing distance.

Complementary Color Tuning by HCl via Phosphorescence-to-Fluorescence Conversion on Insulated Metallopolymer Film and Its Light-Induced Acceleration

An insulated metallopolymer that undergoes phosphorescence-to-fluorescence conversion between complementary colors by an acid-stimulus is proposed as a color-tunable material. A Pt-based phosphorescent metallopolymer, where the conjugated polymeric backbone is insulated by a cyclodextrin, is depolymerized by HCl via acidic cleavage of Pt-acetylide bonds to form a fluorescent monomer. The insulation enables phosphorescence-to-fluorescence conversion to take place in the solid film. Rapid color change was achieved by accelerating the reaction between the metallopolymer and HCl by UV irradiation. These approaches are expected to provide new guidelines for the development of next-generation color-tunable materials and printable sensors based on precise molecular engineering.

A sequence-specific plasmonic loop-mediated isothermal amplification assay with orthogonal color readouts enabled by CRISPR Cas12a

CRISPR Cas12a enables a sequence-specific plasmonic LAMP assay with dual complementary color readouts.

Visual signal evolution along complementary color axes in four bird lineages

Animal color patterns function in varied behavioral contexts including recognition, camouflage and even thermoregulation. The diversity of visual signals may be constrained by various factors, for example, dietary factors, and the composition of ambient environmental light (sensory drive). How have high-contrast and diverse signals evolved within these constraints? In four bird lineages, we present evidence that plumage colors cluster along a line in tetrachromatic color space. Additionally, we present evidence that this line represents complementary colors, which are defined as opposite sides of a line passing through the achromatic point (putatively for higher chromatic contrast). Finally, we present evidence that interspecific color variation over at least some regions of the body is not constrained by phylogenetic relatedness. Thus, we hypothesize that species-specific plumage patterns within these bird lineages evolve by swapping the distributions of a complementary color pair (or dark and light patches in one group, putatively representing an achromatic complementary axis). The relative role of chromatic and achromatic contrasts in discrimination may depend on the environment that each species inhabits.