Encoding in the Dark

Low light scenes often come with acquisition noise, which not only disturbs the viewers, but it also makes video compression harder. These type of videos are often encountered in cinema as a result of artistic perspective or the nature of a scene. Other examples include shots of wildlife (e.g. mobula rays at night in Blue Planet II), concerts and shows, surveillance camera footage and more. Inspired by all above, we are proposing a challenge on encoding low-light captured videos. This challenge intends to identify technology that improves the perceptual quality of compressed low-light videos beyond the current state of the art performance of the most recent coding standards, such as HEVC, AV1, VVC etc. Moreover, this will offer a good opportunity for both experts in the fields of video coding and image enhancement to address this problem. A series of subjective tests will be part of the evaluation, the results of which can be used in a study of the tradeoff between artistic direction and the viewers' preferences, such as mystery movies and some investigation scenes in the film

Pattern variation is linked to anti-predator colouration in butterfly larvae

Prey animals typically try to avoid being detected and/or advertise to would-be predators that they should be avoided. Both anti-predator strategies primarily rely on colour to succeed, but the specific patterning used is also important. While the role of patterning in camouflage is relatively clear, the design features of aposematic patterns are less well understood. Here, we use a comparative approach to investigate how pattern use varies across a phylogeny of 268 species of cryptic and aposematic butterfly larvae, which also vary in social behaviour. We find that longitudinal stripes are used more frequently by cryptic larvae and that patterns putatively linked to crypsis are more likely to be used by solitary larvae. In contrast, aposematic larvae are more likely to use horizontal bands and spots, but we find no differences in the use of individual pattern elements between solitary and gregarious aposematic species. However, solitary aposematic larvae are more likely to display multiple pattern elements, whereas those with no pattern are more likely to be gregarious. Our study advances our understanding of how pattern variation, colouration and social behaviour co-vary across lepidopteran larvae, and highlights new questions about how patterning affects larval detectability and predator responses to aposematic prey

Humans represent the precision and utility of information acquired across fixations dataset

This dataset contrains the behavioural and eyetracking data for the paper: Stewart, E.E.M., Ludwig, C.J.H. & Schütz, A.C. Humans represent the precision and utility of information acquired across fixations. Sci Rep 12, 2411 (2022). https://doi.org/10.1038/s41598-022-06357-7 For results of the supplementary online experiment for this paper, as well as analysis of the images in the Amsterdam Library of Object Images (ALOI) dataset, please see the separate dataset: https://doi.org/10.5281/zenodo.6068096 This dataset also contrains a copy of the ALOI images used in the experiment, originally sourced from https://aloi.science.uva.nl/

Pattern variation is linked to anti-predator colouration in butterfly larvae

Prey animals typically try to avoid being detected and/or advertise to would-be predators that they should be avoided. Both anti-predator strategies primarily rely on colour to succeed, but the specific patterning used is also important. While the role of patterning in camouflage is relatively clear, the design features of aposematic patterns are less well understood. Here, we use a comparative approach to investigate how pattern use varies across a phylogeny of 268 species of cryptic and aposematic butterfly larvae, which also vary in social behaviour. We find that longitudinal stripes are used more frequently by cryptic larvae and that patterns putatively linked to crypsis are more likely to be used by solitary larvae. In contrast, aposematic larvae are more likely to use horizontal bands and spots, but we find no differences in the use of individual pattern elements between solitary and gregarious aposematic species. However, solitary aposematic larvae are more likely to display multiple pattern elements, whereas those with no pattern are more likely to be gregarious. Our study advances our understanding of how pattern variation, colouration and social behaviour co-vary across lepidopteran larvae, and highlights new questions about how patterning affects larval detectability and predator responses to aposematic prey

Pattern variation is linked to anti-predator colouration in butterfly larvae

Prey animals typically try to avoid being detected and/or advertise to would-be predators that they should be avoided. Both anti-predator strategies primarily rely on colour to succeed, but the specific patterning used is also important. While the role of patterning in camouflage is relatively clear, the design features of aposematic patterns are less well understood. Here, we use a comparative approach to investigate how pattern use varies across a phylogeny of 268 species of cryptic and aposematic butterfly larvae, which also vary in social behaviour. We find that longitudinal stripes are used more frequently by cryptic larvae and that patterns putatively linked to crypsis are more likely to be used by solitary larvae. In contrast, aposematic larvae are more likely to use horizontal bands and spots, but we find no differences in the use of individual pattern elements between solitary and gregarious aposematic species. However, solitary aposematic larvae are more likely to display multiple pattern elements, whereas those with no pattern are more likely to be gregarious. Our study advances our understanding of how pattern variation, colouration and social behaviour co-vary across lepidopteran larvae, and highlights new questions about how patterning affects larval detectability and predator responses to aposematic prey

Data from: Background complexity and the detectability of camouflaged targets by birds and humans

Remaining undetected is often key to survival, and camouflage is a widespread solution. However, extrinsic to the animal itself, the complexity of the background may be important. This has been shown in laboratory experiments using artificially patterned prey and backgrounds, but the mechanism remains obscure (not least because ‘complexity’ is a multifaceted concept). In this study, we determined the best predictors of detection by wild birds and human participants searching for the same cryptic targets on trees in the field. We compared detection success to metrics of background complexity and ‘visual clutter’ adapted from the human visual salience literature. For both birds and humans, the factor that explained most of the variation in detectability was the textural complexity of the tree bark as measured by a metric of feature congestion (specifically, many nearby edges in the background). For birds, this swamped any effects of colour match to the local surroundings, although for humans, local luminance disparities between the target and tree became important. For both taxa, a more abstract measure of complexity, entropy, was a poorer predictor. Our results point to the common features of background complexity that affect visual search in birds and humans, and how to quantify them.,Background complexity and the detectability of camouflaged targets by birds and humansRaw data of the experimentraw_data.xlsx

Warning coloration, body size and the evolution of gregarious behavior in butterfly larvae

Many species gain anti-predator benefits by combining gregarious behavior with warning coloration, yet there is debate over which trait evolves first, and which is the secondary adaptive enhancement. Body size can also influence how predators receive aposematic signals, and potentially constrain the evolution of gregarious behavior. To our knowledge, the causative links between the evolution of gregariousness, aposematism and larger body sizes have not been fully resolved. Here, using the most recently resolved butterfly phylogeny and an extensive new dataset of larval traits, we reveal the evolutionary interactions between important traits linked to larval gregariousness. We show that larval gregariousness has arisen many times across the butterflies, and aposematism is a likely prerequisite for gregariousness to evolve. We also find that body size may be an important factor for determining the coloration of solitary, but not gregarious larvae. Additionally, by exposing artificial 'larvae' to wild avian predation, we show that undefended, cryptic 'larvae' are heavily predated when aggregated but benefit from solitariness, whereas the reverse is true for aposematic prey. Our data reinforce the importance of aposematism for gregarious larval survival, whilst identifying new questions about the roles of body size and toxicity in the evolution of grouping behavior

Data from: Perceived duration of brief visual events is mediated by timing mechanisms at the global stages of visual processing

There is a growing body of evidence pointing to the existence of modality-specific timing mechanisms for encoding sub-second durations. For example, the duration compression effect describes how prior adaptation to a dynamic visual stimulus results in participants underestimating the duration of a sub-second test stimulus when it is presented at the adapted location. There is substantial evidence for the existence of both cortical and pre-cortical visual timing mechanisms; however, little is known about where in the processing hierarchy the cortical mechanisms are likely to be located. We carried out a series of experiments to determine whether or not timing mechanisms are to be found at the global processing level. We had participants adapt to random dot patterns that varied in their motion coherence, thus allowing us to probe the visual system at the level of motion integration. Our first experiment revealed a positive linear relationship between the motion coherence level of the adaptor stimulus and duration compression magnitude. However, increasing the motion coherence level in a stimulus also results in an increase in global speed. To test whether duration compression effects were driven by global speed or global motion, we repeated the experiment, but kept global speed fixed while varying motion coherence levels. The duration compression persisted, but the linear relationship with motion coherence was absent, suggesting that the effect was driven by adapting global speed mechanisms. Our results support previous claims that visual timing mechanisms persist at the level of global processing.,Data

BVI-Lowlight: Fully registered datasets for low-light image and video enhancement

Low-light images and video footage often exhibit issues due to the interplay of various parameters such as aperture, shutter speed, and ISO settings. These interactions can lead to distortions, especially in extreme lighting conditions. This distortion is primarily caused by the inverse relationship between decreasing light intensity and increasing photon noise, which gets amplified with higher sensor gain. Additionally, secondary characteristics like white balance and color effects can also be adversely affected and may require post-processing correction. These distortions not only impact the perceived quality of the images but also pose significant challenges for machine learning tasks, including classification and object detection. This is particularly evident when considering the susceptibility of deep learning networks to adversarial examples.The BVI-Lowlight datasets offer fully registered low-light content alongside their corresponding clean and normal light condition ones. This dataset includes both images and videos, enabling the use of supervised learning approaches and performance evaluation through objective metrics such as PSNR and SSIM

BVI-Lowlight: Fully registered datasets for low-light image and video enhancement

Low-light images and video footage often exhibit issues due to the interplay of various parameters such as aperture, shutter speed, and ISO settings. These interactions can lead to distortions, especially in extreme lighting conditions. This distortion is primarily caused by the inverse relationship between decreasing light intensity and increasing photon noise, which gets amplified with higher sensor gain. Additionally, secondary characteristics like white balance and color effects can also be adversely affected and may require post-processing correction. These distortions not only impact the perceived quality of the images but also pose significant challenges for machine learning tasks, including classification and object detection. This is particularly evident when considering the susceptibility of deep learning networks to adversarial examples.The BVI-Lowlight datasets offer fully registered low-light content alongside their corresponding clean and normal light condition ones. This dataset includes both images and videos, enabling the use of supervised learning approaches and performance evaluation through objective metrics such as PSNR and SSIM