Memory Representation of Object Colours

Perception ◽  
1996 ◽  
Vol 25 (1_suppl) ◽  
pp. 185-185 ◽  
Author(s):  
S N Yendrikhovskij ◽  
F J J Blommaert ◽  
H de Ridder
Keyword(s):  
Bivariate Normal Distribution ◽  
Memory Representation ◽  
Natural Scenes ◽  
Colour Space ◽  
Gray Background ◽  
Surface Information ◽  
Chromaticity Coordinates ◽  
Hue Angle ◽  
Similarity Judgments ◽  
Powerful Constraint

Memory colours, ie colours recalled in association with familiar objects, impose a powerful constraint on colour appraisal of images of natural scenes. The purpose of this study is to specify the memory representation of one particular object colour. To this end, the colour of a banana was manipulated by varying hue-angle and saturation in the CIELUV colour space. Subjects' task was to rate the similarity in colour of the resulting banana samples displayed on the screen to the typical ripe banana stored in their mind. In order to examine the dependence of memory colour on texture information and context, three ways of presentation were used: original (banana among other fruit), isolated (the same banana against a homogenous gray background), and contour (silhouette of the banana with its average colour against the gray background). The relationships between the similarity judgments and chromaticity coordinates of the manipulated banana-represented points in the CIELUV colour space is described by a bivariate normal distribution with four parameters: two means and two variances of the Gaussians on the hue and saturation dimensions. For all three types of presentation, the variance of hue is significantly smaller than the variance of saturation; this suggests that memory description of hue is more precise than that of saturation. The data show systematic differences in the hue of memory colour between the original, isolated, and contour presentations of the banana. A model describing the hue shift in terms of illuminant and surface information content in the images is discussed.

scholarly journals Automatic gravure print feature determination at production speeds

2003 ◽  
Vol 217 (8) ◽  
pp. 1101-1110 ◽  
Author(s):  
N Brown ◽  
M R Jackson ◽  
R M Parkin
Keyword(s):  
Feature Recognition ◽  
Colour Space ◽  
Spectral System ◽  
Chromaticity Coordinates ◽  
Video Systems ◽  
Examination Methods ◽  
Software And Hardware ◽  
Progressive Scan ◽  
Feature System ◽  
Rgb System

This paper describes the development of a non-contact system for measuring the colour of printed material at web speeds, in addition to gravure-printed dot feature recognition. The system proposed uses a non-contact spectrophotometer based on a holographic grating, in conjunction with a conventional monochrome area scan camera, from which colour spectral data are extracted, while a xenon flash is used to illuminate colour samples. Dot features are captured by a magnification lens, in conjunction with a progressive scan camera. Software and hardware details of the system are given, together with the underlying mathematics for colour space conversion and measurement. Conversion equations from X, Y, Z chromaticity coordinates to the RGB system are presented, and also equations to convert from the L* a* b* colour space to X, Y, Z chromaticity coordinates. Experimental results are presented whereby the non-contact spectral system is shown to perform to a colour tolerance exceeding that of conventional colour video systems, and where performance of the dot feature system is comparable with traditional static examination methods using a microscope.

Chromatic Cues for Face Detection in Natural Scenes

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 294-294
Author(s):  
A Oliva ◽  
S Akamatsu ◽  
P G Schyns
Keyword(s):  
Face Detection ◽  
Reaction Times ◽  
Detection Task ◽  
Natural Scenes ◽  
Colour Space ◽  
Affect Detection ◽  
Detection Of Objects ◽  
Chromatic Cues ◽  
Colour Histograms ◽  
Euclidian Distances

One of the challenging problems of human and machine vision is the detection of objects against complex backgrounds. Our research addresses the question of how faces can be very quickly detected in naturalistic scenes on the basis of luminance and chromatic cues. Although luminance information varies with pose and illumination differences, chromatic information is by and large invariant under these transformations. Hence, chromatic information might be a very powerful cue for segmentation and detection. We compared faces of different pigmentation against background scenes of different colours. Specifically, colour histograms were computed in a perceptually uniform colour space (L*u*v*). We computed the Euclidian distances between the averages of the colour histograms of faces and scenes in L*u*v*. This metric was used to calibrate the contrast between face and scene colour in the experimental design. In a face detection task, subjects saw faces against scene backgrounds at a different distance in colour space. Each combination face - scene was presented for 120 ms (to prevent saccadic explorations), and the subject's task was to indicate whether or not a face was present. Controls involved face - scene pairs on an isoluminant background. Results revealed that luminance information did not affect detection on the basis of chromatic cues. Importantly, the metric of detectability in L*u*v* space between scene and faces predicted reaction times to detection.

The effect of UV radiation in Xenotest 450 on the colour of steamed beech wood during the process of simulated ageing

2019 ◽  
Vol 106 ◽  
pp. 114-120
Author(s):  
LADISLAV DZURENDA
Keyword(s):  
Uv Radiation ◽  
Wave Length ◽  
Beech Wood ◽  
Exposure Period ◽  
Rate Of Change ◽  
Accelerated Ageing ◽  
Colour Difference ◽  
Colour Space ◽  
Yellow Colour ◽  
Hue Angle

The effect of UV radiation in Xenotest 450 on the colour of steamed beech wood during the process of simulated ageing .The aim of the paper is to present the changes in colour of steamed beech wood in the pocess of simulated ageing in Xenotest 450. Red-brown colour of beech wood with the coordinates of L* = 62.6 ± 2.8; a* = 10.9 ± 2.3; b* = 17.1 ± 1.3 in the CIE L*a*b* colour space resulted from the mode of colour modification of wood with saturated vapour with the temperature of t = 120 ± 2 oC for τ = 6.5 hours. The surface of samples after drying to the moisture content of w = 12 % and planing was irradiated in Xenotest 450 with xenon gasdischarge tube by UV radiation with the wave length of 340 nm. Accelerated ageing experiment ran in exposure period A1 for seven days. Simulated ageing of thermally treated beech wood showed that due to UV radiation, the wood surface is turning pale and brown. The change in the lightness coordinate by the value of ΔL* = + 6.7 shows the rate of change in the surface lightness and the changes in the values of chromatic coordinates of red colour by the value of Δa* = - 0.1 and yellow colour by Δb* = + 12.3 shows the rate of getting brown. Therefore the hue angle increases from h*ab = 57.5 ° to h°ab = 69.8 °. The value of the total colour difference resulting from the process of ageing is ΔE* = 14.5.

scholarly journals Detecting Novelty and Significance

2010 ◽  
Vol 22 (2) ◽  
pp. 404-411 ◽  
Author(s):  
Vera Ferrari ◽  
Margaret M. Bradley ◽  
Maurizio Codispoti ◽  
Peter J. Lang
Keyword(s):  
Oddball Paradigm ◽  
Memory Representation ◽  
Natural Scenes ◽  
Significant Information ◽  
Stimulus Significance ◽  
Passive Viewing ◽  
Current Context ◽  
Viewing Context ◽  
P3 Component ◽  
A Current

Studies of cognition often use an “oddball” paradigm to study effects of stimulus novelty and significance on information processing. However, an oddball tends to be perceptually more novel than the standard, repeated stimulus as well as more relevant to the ongoing task, making it difficult to disentangle effects due to perceptual novelty and stimulus significance. In the current study, effects of perceptual novelty and significance on ERPs were assessed in a passive viewing context by presenting repeated and novel pictures (natural scenes) that either signaled significant information regarding the current context or not. A fronto-central N2 component was primarily affected by perceptual novelty, whereas a centro-parietal P3 component was modulated by both stimulus significance and novelty. The data support an interpretation that the N2 reflects perceptual fluency and is attenuated when a current stimulus matches an active memory representation and that the amplitude of the P3 reflects stimulus meaning and significance.

Colour Change Analysis of Fig Fruit during Microwave Drying

2013 ◽  
Vol 9 (1) ◽  
pp. 107-114 ◽  
Author(s):  
Faroogh Sharifian ◽  
Asad Modarres-Motlagh ◽  
Mohammad Hasan Komarizade ◽  
Ali M. Nikbakht
Keyword(s):  
Microwave Power ◽  
Colour Change ◽  
Microwave Drying ◽  
Colour Space ◽  
Change Analysis ◽  
Power Intensity ◽  
Before And After ◽  
Yellow Orange ◽  
Hue Angle ◽  
Orange Colour

AbstractInvestigation of qualitative indices for the pulsed microwave dried figs (Ficus carica L.) is accomplished through image processing techniques. Three hundred colour pictures of fig fruit before and after drying were prepared in RGB colour space. After converting the RGB colour space into Lab units, colour values in Lab units were analysed before and after drying at five levels of microwave power intensity and six pulsing ratio levels. Kinetic parameters for the colour change were determined using the total colour change parameter, chroma, hue angle and browning index. The results showed that the L value decreases with the pulsing ratio and increases with microwave power intensity while a values remains constant with the microwave power intensity. Values of hue angle for dried fig varied between 1.21 and 1.32 radian, i.e. the dried fruits presented an appealing yellow/orange colour. Additionally, increasing microwave power intensity led to higher browning indices. Based on the resulting values, an optimized microwave drying of fig will be achieved serving as a tool for enhanced economical processing of the fruit.

scholarly journals Colour analysis of syrup from malted and unmalted rice of different varieties

2020 ◽  
Vol 12 (1) ◽  
pp. 130-138 ◽  
Author(s):  
Chijioke Maduka Osuji ◽  
Chigozie Emmanuel Ofoedu ◽  
Gloria Chienyenwa Omeire ◽  
Moses Ojukwu
Keyword(s):  
Visible Region ◽  
Colour Difference ◽  
Colour Space ◽  
Brown Colour ◽  
Significant Difference ◽  
Hue Angle ◽  
Hydrolyzing Enzymes ◽  
Cie Lab ◽  
Starch Hydrolyzing Enzymes ◽  
Colour Chart

The colour of rice syrup produced from flours of malted and unmalted rice of different varieties treated with a combination of starch hydrolyzing enzymes were analysed using CIE-LAB Spectrophotometric colorimeter after being filtered and/or centrifuged. The resulting syrups were processed as filtered unmalted hydrolyzed rice (FUHR), filtered malted hydrolyzed rice (FMHR), centrifuged unmalted hydrolyzed rice (CUHR) and centrifuged malted hydrolyzed rice (CMHR). Results showed that L* ranged from 60.16 to 68.57, a* ranged from 10.49 to 11.13 and b* ranged from 55.34 to 64.56. The magnitude of the colour values was an indication of the intensity of the rice syrup colour. Hue angle (oH*) ranged from 79.08o to 80.36o indicating less yellow in the CIE-LAB colour space and brown colour spectrum in the visible region of opponent colour chart. Total colour difference (ΔE) of syrups ranged from 0.50 to 1.72 for ΔEunmalted while ΔEmalted ranged from 0.49 to 1.76. However, the ΔEfiltered ranged from 5.89 to 11.19 while ΔEcentrifuged ranged from 5.54 to 9.47 indicating that filtration and centrifugation contributed to non-significant difference (p>0.05) in colour attributes (ΔE) of the rice syrup, whereas very distinct colour difference (ΔE) was observed between rice syrups from malted and unmalted samples.

scholarly journals Genesis and Influencing Factors of the Colour of Chrysoprase: Colourimetric Analysis Based on the Cie 1976 L*a*b* Uniform Colour Space

2021 ◽  
Author(s):  
Yuansheng Jiang ◽  
Ying Guo
Keyword(s):  
Electron Microscopy ◽  
Visible Spectrum ◽  
Fluorescent Lamp ◽  
Colour Space ◽  
X Ray ◽  
Cr Content ◽  
Ni Content ◽  
Transmission Electron ◽  
Hue Angle ◽  
Transmission Window

Abstract The colour of chrysoprase is produced by Ni cations and influenced by other transition-metal cations and crystallinity. Presented here is a study of the origin of chrysoprase colour and an exploration of the factors that influence it from the perspective of gemstone chromaticity. Transmission electron microscopy and X-ray fluorescence, ultraviolet–visible and Raman spectroscopies are used to investigate 41 gem-quality chrysoprase samples, and the results show that chrysoprase colour results from nanometre-size inclusions of pimelite. Under a 6504-K fluorescent lamp, chrysoprase colour is divided into the grades of fancy, fancy intense and fancy deep. The lightness of chrysoprase is affected mainly by its Cr content, the chroma is affected by its Ni content and the hue angle is affected by the sum of its Cr and Fe contents. Chrysoprase hue and chroma are related significantly to the transmission window that occurs between the two main bands centred at 380 and 660 nm and the absorption peak at 660 nm in the ultraviolet–visible spectrum. Chrysoprase with low crystallinity has more Ni and a higher chroma.

Detector strategies for environmental scanning electron microscopy

1992 ◽  
Vol 50 (2) ◽  
pp. 1296-1297
Author(s):  
Klaus-Ruediger Peters
Keyword(s):  
High Vacuum ◽  
Environmental Scanning Electron Microscopy ◽  
Charge Carriers ◽  
Environmental Scanning ◽  
Surface Information ◽  
X Ray ◽  
Detector Electrode ◽  
Electrons And Ions ◽  
Low Energy Electrons ◽  
Environmental Sem

Environmental SEM operate at specimen chamber pressures of ∼20 torr (2.7 kPa) allowing stabilization of liquid water at room temperature, working on rugged insulators, and generation of an environmental secondary electron (ESE) signal. All signals available in conventional high vacuum instruments are also utilized in the environmental SEM, including BSE, SE, absorbed current, CL, and X-ray. In addition, the ESEM allows utilization of the flux of charge carriers as information, providing exciting new signal modes not available to BSE imaging or to conventional high vacuum SEM.In the ESEM, at low vacuum, SE electrons are collected with a “gaseous detector”. This detector collects low energy electrons (and ions) with biased wires or plates similar to those used in early high vacuum SEM for SE detection. The detector electrode can be integrated into the first PLA or positioned at any other place resulting in a versatile system that provides a variety of surface information.

Individual differences in colourfulness judgments of images of natural scenes

1995 ◽  
Author(s):  
S.N. Yendrikhovskij ◽  
H. DE Ridder ◽  
E.A. Fedorovskaya
Keyword(s):  
Individual Differences ◽  
Natural Scenes
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