Human cortical processing of colour and pattern

Investigated human visual processing of simple two-colour patterns using a delayed match to sample paradigm with positron emission tomography (PET). This study is unique in that the authors specifically designed the visual stimuli to be the same for both pattern and colour recognition with all patterns being abstract shapes not easily verbally coded composed of two-colour combinations. The authors did this to explore those brain regions required for both colour and pattern processing and to separate those areas of activation required for one or the other. 10 right-handed male volunteers aged 18–35 yrs were recruited. The authors found that both tasks activated similar occipital regions, the major difference being more extensive activation in pattern recognition. A right-sided network that involved the inferior parietal lobule, the head of the caudate nucleus, and the pulvinar nucleus of the thalamus was common to both paradigms. Pattern recognition also activated the left temporal pole and right lateral orbital gyrus, whereas colour recognition activated the left fusiform gyrus and several right frontal regions.

Change in colour appearance of small defocused lights

Small long wavelength lights (≤ 1’ arc) change colour appearance with positive defocus, appearing yellow or white. I investigated influences of longitudinal chromatic aberration and monochromatic aberrations on colour appearance of small narrow band lights. Seven cyclopleged participants viewed a small light (1’ arc diameter, λmax range 510 - 628 nm) centred within a 4.6’ black annulus and surrounded by a uniform white field under photopic light levels. An optical trombone varied focus. Participants were required to vary the focus by moving the optical trombone in either positive or negative direction and report when they noticed a change in appearance of the defocused narrow band light. Longitudinal chromatic aberration was controlled using a Powell achromatizing lens and its doublet and triplet components that neutralized, doubled and reversed the eye’s chromatic aberration, respectively. Changes in colour appearance for a 628 nm light occurred without any lens at +0.5 ± 0.2D defocus and with the doublet at +0.6 ± 0.2 D. The achromatizing lens did not affect appearance and the phenomenon was evident with the triplet for negative defocus (-0.5 ± 0.3 D). Adaptive optics correction of astigmatism and higher order monochromatic aberration did not affect magnitude significantly. Colour changes occurred despite a range of participant L/M cone ratios. Direction of change in colour appearance was reversed for short compared to long wavelengths. We conclude that longitudinal chromatic aberrations, but not monochromatic aberrations, are involved in changing appearance of small lights with defocus. Additional neuronal mechanisms that may contribute to the colour changes are considered.

Effect of optical aberrations on the colour appearance of small lights

Purpose: Small red lights (one minute of arc or less) change colour appearance with positive defocus. We investigated the influence of longitudinal chromatic aberration and monochromatic aberrations on the colour appearance of small narrow band lights. Methods: Seven cyclopleged, trichromatic observers viewed a small light (one minute of arc, λmax = 510, 532, 550, 589, 620, 628 nm, approximately 19 per cent Weber contrast) centred within a black annulus (4.5 minutes of arc) and surrounded by a uniform white field (2,170 cd/m2). Pupil size was four millimetres. An optical trombone varied focus. Longitudinal chromatic aberration was controlled with a two component Powell achromatising lens that neutralises the eye’s chromatic aberration; a doublet that doubles and a triplet that reverses the eye’s chromatic aberration. Astigmatism and higher order monochromatic aberrations were corrected using adaptive optics. Results: Observers reported a change in appearance of the small red light (628 nm) without the Powell lens at +0.49 ± 0.21 D defocus and with the doublet at +0.62 ± 0.16 D. Appearance did not alter with the Powell lens, and five of seven observers reported the phenomenon with the triplet for negative defocus (-0.80 ± 0.47 D). Correction of aberrations did not significantly affect the magnitude at which the appearance of the red light changed (+0.44 ± 0.18 D without correction; +0.46 ± 0.16 D with correction). The change in colour appearance with defocus extended to other wavelengths (λmax = 510 to 620 nm), with directions of effects being reversed for short wavelengths relative to long wavelengths. Conclusions: Longitudinal chromatic aberrations but not monochromatic aberrations are involved in changing the appearance of small lights with defocus.

Corneal confocal microscopy : a novel means to detect nerve fibre damage in idiopathic small fibre neuropathy

Patients with idiopathic small fibre neuropathy (ISFN) have been shown to have significant intraepidermal nerve fibre loss and an increased prevalence of impaired glucose tolerance (IGT). It has been suggested that the dysglycemia of IGT and additional metabolic risk factors may contribute to small nerve fibre damage in these patients. Twenty-five patients with ISFN and 12 aged-matched control subjects underwent a detailed evaluation of neuropathic symptoms, neurological deficits (Neuropathy deficit score (NDS); Nerve Conduction Studies (NCS); Quantitative Sensory Testing (QST) and Corneal Confocal Microscopy (CCM)) to quantify small nerve fibre pathology. Eight (32%) patients had IGT. Whilst all patients with ISFN had significant neuropathic symptoms, NDS, NCS and QST except for warm thresholds were normal. Corneal sensitivity was reduced and CCM demonstrated a significant reduction in corneal nerve fibre density (NFD) (Pb0.0001), nerve branch density (NBD) (Pb0.0001), nerve fibre length (NFL) (Pb0.0001) and an increase in nerve fibre tortuosity (NFT) (Pb0.0001). However these parameters did not differ between ISFN patients with and without IGT, nor did they correlate with BMI, lipids and blood pressure. Corneal confocal microscopy provides a sensitive non-invasive means to detect small nerve fibre damage in patients with ISFN and metabolic abnormalities do not relate to nerve damage.

An investigation of rail condition monitoring by Fibre Bragg Grating sensors

Condition monitoring on rails and train wheels is vitally important to the railway asset management and the rail-wheel interactions provide the crucial information of the health state of both rails and wheels. Continuous and remote monitoring is always a preference for operators. With a new generation of strain sensing devices in Fibre Bragg Grating (FBG) sensors, this study explores the possibility of continuous monitoring of the health state of the rails; and investigates the required signal processing techniques and their limitations.

Shifting interpretations of interiors and buildings: the impact of colour

The ability of a designer – for example, interior designer, architect, landscape architect, etc. – to design for a particular target group (user and/or clients) is potentially enhanced through more targeted studies relating colour in situ. The study outlined in this paper involved participant responses to five achromatic scenes of different built environments prior to viewing the same scenes in colour. Importantly, in this study the participants, who were young designers, came to realise that colour potentially holds the power to impact on the identity of an architectural form, an interior space and/or particular elements such as doorways, furniture settings, etc., as well as influence atmosphere. Prior to discussing the study, a selection of other research, which links colour to meaning and emotions, introduces how people understand and/or feel in relation to colour. For example, yellow is said to be connected to happiness; or red evokes feelings of anger. Secondly, the need for spatial designers to understand colour in context is raised. An overview of the study is then provided. It was found that the impact of colour includes a shift in perception of aspects such as its atmosphere and youthfulness. Through studio/class discussions it was also noted the predicted age of the place, the function, and in association, the potential users when colour was added (or deleted) were often challenged.

Graphcut-based interactive segmentation using colour and depth cues

Segmentation of novel or dynamic objects in a scene, often referred to as background sub- traction or foreground segmentation, is critical for robust high level computer vision applica- tions such as object tracking, object classifca- tion and recognition. However, automatic real- time segmentation for robotics still poses chal- lenges including global illumination changes, shadows, inter-re ections, colour similarity of foreground to background, and cluttered back- grounds. This paper introduces depth cues provided by structure from motion (SFM) for interactive segmentation to alleviate some of these challenges. In this paper, two prevailing interactive segmentation algorithms are com- pared; Lazysnapping [Li et al., 2004] and Grab- cut [Rother et al., 2004], both based on graph- cut optimisation [Boykov and Jolly, 2001]. The algorithms are extended to include depth cues rather than colour only as in the original pa- pers. Results show interactive segmentation based on colour and depth cues enhances the performance of segmentation with a lower er- ror with respect to ground truth.

Investigation of hybridized polyurethane, glass fibre reinforced cement and steel laminate in structural floor plate systems

Sandwich components have emerged as light weight, efficient, economical, recyclable and reusable building systems which provide an alternative to both stiffened steel and reinforced concrete. These components are made of composite materials in which two metal face plates or Glassfibre Reinforced Cement (GRC) layers are bonded and form a sandwich with light weight compact polyurethane (PU) elastomer core. Existing examples of product applications are light weight sandwich panels for walls and roofs, Sandwich Plate System (SPS) for stadia, arena terraces, naval construction and bridges and Domeshell structures for dome type structures. Limited research has been conducted to investigate performance characteristics and applicability of sandwich or hybrid materials as structural flooring systems. Performance characteristics of Hybrid Floor Plate Systems comprising GRC, PU and Steel have not been adequately investigated and quantified. Therefore there is very little knowledge and design guidance for their application in commercial and residential buildings. This research investigates performance characteristics steel, PU and GRC in Hybrid Floor Plate Systems (HFPS) and develops a new floor system with appropriate design guide lines.

Urban identity and colour : the case of Tirana, Albania

When an artist is put in charge of a city, he will use the town as his canvas. Edi Rama became Mayor of Tirana in 2000 and since them has undertaken an unusual and colourful renewal program for the Albania capital.