Looking through the eyes of the painter: from visual perception to non-photorealistic rendering

In this paper we present a brief overview of the processing in the primary visual cortex, the multi-scale line/edge and keypoint representations, and a model of brightness perception. This model, which is being extended from 1D to 2D, is based on a symbolic line and edge interpretation: lines are represented by scaled Gaussians and edges by scaled, Gaussian-windowed error functions. We show that this model, in combination with standard techniques from graphics, provides a very fertile basis for non-photorealistic image rendering

Cortical 3D Face Recognition Framework

Empirical studies concerning face recognition suggest that faces may be stored in memory by a few canonical representations. In cortical area V1 exist double-opponent colour blobs, also simple, complex and end-stopped cells which provide input for a multiscale line/edge representation, keypoints for dynamic routing and saliency maps for Focus-of-Attention. All these combined allow us to segregate faces. Events of different facial views are stored in memory and combined in order to identify the view and recognise the face including facial expression. In this paper we show that with five 2D views and their cortical representations it is possible to determine the left-right and frontal-lateral-profile views and to achieve view-invariant recognition of 3D faces

Artistic rendering of the visual cortex

In this paper we explain the processing in the first layers of the visual cortex by simple, complex and endstopped cells, plus grouping cells for line, edge, keypoint and saliency detection. Three visualisations are presented: (a) an integrated scheme that shows activities of simple, complex and end-stopped cells, (b) artistic combinations of selected activity maps that give an impression of global image structure and/or local detail, and (c) NPR on the basis of a 2D brightness model. The cortical image representations offer many possibilities for non-photorealistic rendering

Cortical multiscale line-edge disparity model

Most biological approaches to disparity extraction rely on the disparity energy model (DEM). In this paper we present an alternative approach which can complement the DEM model. This approach is based on the multiscale coding of lines and edges, because surface structures are composed of lines and edges and contours of objects often cause edges against their background. We show that the line/edge approach can be used to create a 3D wireframe representation of a scene and the objects therein. It can also significantly improve the accuracy of the DEM model, such that our biological models can compete with some state-of-the-art algorithms from computer vision

Building the what and where systems: multi-scale lines, edges and keypoints

Computer vision for realtime applications requires tremendous computational power because all images must be processed from the first to the last pixel. Ac tive vision by probing specific objects on the basis of already acquired context may lead to a significant reduction of processing. This idea is based on a few concepts from our visual cortex (Rensink, Visual Cogn. 7, 17-42, 2000): (1) our physical surround can be seen as memory, i.e. there is no need to construct detailed and complete maps, (2) the bandwidth of the what and where systems is limited, i.e. only one object can be probed at any time, and (3) bottom-up, low-level feature extraction is complemented by top-down hypothesis testing, i.e. there is a rapid convergence of activities in dendritic/axonal connections

Constructing and Visualizing High-Quality Classifier Decision Boundary Maps dagger

Visualizing decision boundaries of machine learning classifiers can help in classifier design, testing and fine-tuning. Decision maps are visualization techniques that overcome the key sparsity-related limitation of scatterplots for this task. To increase the trustworthiness of decision map use, we perform an extensive evaluation considering the dimensionality-reduction (DR) projection techniques underlying decision map construction. We extend the visual accuracy of decision maps by proposing additional techniques to suppress errors caused by projection distortions. Additionally, we propose ways to estimate and visually encode the distance-to-decision-boundary in decision maps, thereby enriching the conveyed information. We demonstrate our improvements and the insights that decision maps convey on several real-world datasets

Stimulated Brillouin scattering by surface acoustic waves in lithium niobate waveguides

We numerically demonstrate that Lithium Niobate on Insulator (LNOI) waveguides may support confined short-wavelength surface acoustic waves that interact strongly with optical fields through backward stimulated Brillouin scattering in both $Z$ and $X$-cut orientation. We conduct fully anisotropic simulations that consider not only moving boundary and photoelastic forces, but also roto-optic forces for the Brillouin interaction. Our results indicate that photoelasticity dominates the Brillouin gain and can reach as high as $G_{B}/Q_{m}$ = 0.43 W$^{-1}$m$^{-1}$ in standard ridge waveguide

Evidences for a new role of miR-214 in chondrogenesis

miR-214 is known to play a role in mammalian skeletal development through inhibition of osteogenesis and stimulation of osteoclastogenesis, but data regarding other vertebrates, as well as a possible role in chondrogenesis, remain unknown. Here, we show that miR-214 expression is detected in bone and cartilage of zebrafish skeleton, and is downregulated during murine ATDC5 chondrocyte differentiation. Additionally, we observed a conservation of the transcriptional regulation of miR-214 primary transcript Dnm3os in vertebrates, being regulated by Ets1 in ATDC5 chondrogenic cells. Moreover, overexpression of miR-214 in vitro and in vivo mitigated chondrocyte differentiation probably by targeting activating transcription factor 4 (Atf4). Indeed, miR-214 overexpression in vivo hampered cranial cartilage formation of zebrafish and coincided with downregulation of atf4 and of the key chondrogenic players sox9 and col2a1. We show that miR-214 overexpression exerts a negative role in chondrogenesis by impacting on chondrocyte differentiation possibly through conserved mechanisms.Calouste Gulbenkian Foundation (program "Na Fronteira das Ciencias da Vida"); FCT [UID/Multi/04326/2013, PEst-C/MAR/LA0015/2011, SFRH/BD/38607/2007, SFRH/BPD/45034/2008, SFRH/BPD/111289/2015]; European Commission (ERDF-COMPETE) [PEst-C/MAR/LA0015/2011]info:eu-repo/semantics/publishedVersio