Measurements of ‘Von Kries’ Contrast Colours

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 42-42 ◽  
Author(s):  
P Whittle ◽  
L Arend
Keyword(s):  
Luminance Contrast ◽  
Second Order ◽  
Logarithmic Function ◽  
Binocular Field ◽  
First Approximation ◽  
Cone Axis ◽  
Multiplicative Shift

At two previous ECVPs we showed demonstrations and preliminary measurements of contrast colours in a haploscopic display. Colours were presented in different uniform surrounds to the two eyes, superimposed in the binocular field so that they appeared to be in the same surround. Here we report more extensive matching experiments. The principal results are as follows: (1) To a first approximation, in a log MacLeod - Boynton space, perceived colour is determined by the surround-to-colour vector (SCV). The remaining results are second-order deviations from this von Kries scheme. (2) Increment colours are tinged with the hue of the surround, even though that surround hue cannot be seen. This effect of the sign of luminance contrast seems to be just a multiplicative shift: otherwise, increment and decrement data can be superimposed. (3) SCVs for a constant perceived colour shrink and expand slightly with movement along the S-cone axis, suggesting that the transform of S-cone excitation is less compressive than a logarithmic function. (4) SCVs show consistent small rotations, suggesting that L- M and S-( L+ M) axes are not completely independent.

Metaontology

2018 ◽  
Author(s):  
Uriah Kriegel
Keyword(s):  
Second Order ◽  
Order Property ◽  
First Order ◽  
First Approximation

Brentano’s theory of judgment serves as a springboard for his conception of reality, indeed for his ontology. It does so, indirectly, by inspiring a very specific metaontology. To a first approximation, ontology is concerned with what exists, metaontology with what it means to say that something exists. So understood, metaontology has been dominated by three views: (i) existence as a substantive first-order property that some things have and some do not, (ii) existence as a formal first-order property that everything has, and (iii) existence as a second-order property of existents’ distinctive properties. Brentano offers a fourth and completely different approach to existence talk, however, one which falls naturally out of his theory of judgment. The purpose of this chapter is to present and motivate Brentano’s approach.

Mixing and the Jet Flap

1956 ◽  
Vol 7 (2) ◽  
pp. 85-105 ◽  
Author(s):  
B. S. Stratford
Keyword(s):  
First Principles ◽  
Second Order ◽  
Experimental Results ◽  
Order Effects ◽  
List Type ◽  
Two Dimensional ◽  
Form Drag ◽  
First Approximation ◽  
Close Proximity ◽  
Thrust Characteristics

SummaryOne of the main problems associated with the “ Jet Flap ” concerns the discrepancy in thrust between idealised theory and the experimental results. This discrepancy is attributable to the mixing with the surrounding flow of the thin two-dimensional jet while still in close proximity to the aerofoil. The effect of the mixing may be calculated to a first approximation from a formula derivable from first principles, while certain second order effects, which can be significant, may be considered qualitatively.It is concluded that.(i) the full thrust should be experienced by a jet flapped aircraft at cruise,(ii) it should be possible to attain a low form drag at cruise in comparison with a conventional aircraft,(iii) at take-off, an aircraft using a shrouded jet flap would have better thrust recovery than one using a pure jet flap (which shows appreciable losses),(iv) the use of by-pass engines would further improve the thrust characteristics,(v) the practical gains from thrust augmentation, as obtained by controlling the mixing, seem likely to be small.

scholarly journals XXXIII. On the figure of the earth

1826 ◽  
Vol 116 ◽  
pp. 548-578 ◽  
Keyword(s):  
Present State ◽  
Royal Society ◽  
Mathematical Theory ◽  
Second Order ◽  
The Earth ◽  
First Approximation ◽  
Figure Of The Earth ◽  
The Subject ◽  
The Difference

The ellipticity of the earth, deduced by Captain Sabine from a series of pendulum experiments the most extensive, and apparently the most deserving of confidence, that has ever been made, differs considerably from that which, as is generally believed, is indicated by geodetic measures. The difference can only be explained by errors of observation, by peculiarities of local circumstances, or by some defect in the theory which connects the figure of the earth with the variation of gravity on its surface: under the last head may be placed defects in the mathematical part of the theory, and errors in the assumptions of the original constitution and present state of the earth. It was with a view to ascertain the sufficiency of the mathematical theory, that I undertook the investigations contained in this paper. The celebrated proposition called Clairaut's theorem, by which the earth's ellipticity is inferred from the variation of gravity on its surface, is obtained only by the rejection of the squares and higher powers of the ellipticity. It is by the same rejection that the figure of the earth, supposed a heterogeneous fluid, is proved to be an elliptic spheroid. It appeared therefore probable, that a more accurate theory might introduce some modification into Clairaut's theorem, and might also show he figure of the earth to differ from an ellipsoid ; and there was no reason to think that the first approximation to that figure was more accurate, than the first approximation to the motion of the moon’s perigee. The result of my investigation does not at all serve to reconcile the pendulum observations made by Captain Sabine with the measures of degrees : and with respect to one object, which I hoped to obtain, I am therefore completely unsuccessful. The theory shows, however, that the earth’s figure, on the usual suppositions as to its constitution, is not an elliptic spheroid; and the formulæ which I have obtained will give the means of determining very exactly the figure of the earth, when the experiments on the variation of gravity, or the measures of arcs on the earth’s surface, shall be thought sufficiently accurate. As the subject is one whose interest is not confined to the present time, I have ventured to offer my investigations to the Royal Society. The first part of the following sheets contains the theory of the heterogeneous earth, pushed so far as to include all the terms of the second order: it is succeeded by a comparison of this theory with Captain Sabine’s results, and with the best arcs of the meridian that have been measured and in the conclusion, I have offered some suggestions on the propriety of repeating some of these measures.

scholarly journals Fibonacci Sequence and Series by Second Order Difference Operator with Logarithmic Function

10.26524/cm39 ◽  
2018 ◽  
Vol 2 (2) ◽  
pp. 51-60
Author(s):  
Rajiniganth P ◽  
Britto Antony Xavier G
Keyword(s):  
Difference Operator ◽  
Fibonacci Sequence ◽  
Second Order ◽  
Logarithmic Function ◽  
Order Difference

Visual Inter-Attribute Contour Completion

Perception ◽  
10.1068/p3222 ◽  
2001 ◽  
Vol 30 (7) ◽  
pp. 855-865 ◽  
Author(s):  
Leo Poom
Keyword(s):  
Binocular Disparity ◽  
Luminance Contrast ◽  
Second Order ◽  
Temporal Contrast ◽  
Pictorial Cues ◽  
Visual Phenomenon ◽  
Completion Process ◽  
Contour Completion

A new visual phenomenon, inter-attribute illusory (completed) contours, is demonstrated. Contour completions are perceived between any combination of spatially separate pairs of inducing elements (Kanizsa-like ‘pacman’ figures) defined either by pictorial cues (luminance contrast or offset gratings), temporal contrast (motion, second-order-motion or ‘phantom’ contours), or binocular-disparity contrast. In a first experiment, observers reported the perceived occurrence of contour completion for all pair combinations of inducing elements. In a second experiment they rated the perceived clarity of the completed contours. Both methods generated similar results—contour completions were perceived even though the inducing elements were defined by different attributes. Ratings of inter-attribute clarity were no lower than in either of the two corresponding intra-attribute conditions and seem to be the average of these two ratings. The results provide evidence for the existence of attribute-invariant Gestalt processes, and on a mechanistic level indicate that the completion process operates on attribute-invariant contour detectors.

scholarly journals Processing of first- and second-order motion signals by neurons in area MT of the macaque monkey

1998 ◽  
Vol 15 (2) ◽  
pp. 305-317 ◽  
Author(s):  
LAWRENCE P. O'KEEFE ◽  
J. ANTHONY MOVSHON
Keyword(s):  
Visual Motion ◽  
Luminance Contrast ◽  
Macaque Monkey ◽  
Small Sample ◽  
Second Order ◽  
Spatial Modulation ◽  
Motion Processing ◽  
Motion Sensors ◽  
Area Mt ◽  
First Order

Extrastriate cortical area MT is thought to process behaviorally important visual motion signals. Psychophysical studies suggest that visual motion signals may be analyzed by multiple mechanisms, a “first-order” one based on luminance, and a “second-order” one based upon higher level cues (e.g. contrast, flicker). Second-order motion is visible to human observers, but should be invisible to first-order motion sensors. To learn if area MT is involved in the analysis of second-order motion, we measured responses to first- and second-order gratings of single neurons in area MT (and in one experiment, in area V1) in anesthetized, paralyzed macaque monkeys. For each neuron, we measured directional and spatio-temporal tuning with conventional first-order gratings and with second-order gratings created by spatial modulation of the flicker rate of a random texture. A minority of MT and V1 neurons exhibited significant selectivity for direction or orientation of second-order gratings. In nearly all cells, response to second-order motion was weaker than response to first-order motion. MT cells with significant selectivity for second-order motion tended to be more responsive and more sensitive to luminance contrast, but were in other respects similar to the remaining MT neurons; they did not appear to represent a distinct subpopulation. For those cells selective for second-order motion, we found a correlation between the preferred directions of first- and second-order motion, and weak correlations in preferred spatial frequency. These cells preferred lower temporal frequencies for second-order motion than for first-order motion. A small proportion of MT cells seemed to remain selective and responsive for second-order motion. None of our small sample of V1 cells did. Cells in this small population, but not others, may perform “form-cue invariant” motion processing (Albright, 1992).

scholarly journals Possible significance of spatial heterogeneities of local visual features for face perception

F1000Research ◽  
2015 ◽  
Vol 4 ◽  
pp. 10
Author(s):  
Vitaly V. Babenko ◽  
Daria S. Alekseeva ◽  
Denis V. Yavna
Keyword(s):  
Spatial Heterogeneity ◽  
Random Sequence ◽  
Luminance Contrast ◽  
Second Order ◽  
Visual Features ◽  
Living Things ◽  
Spatial Frequencies ◽  
Average Luminance ◽  
Striate Neurons ◽  
Unfamiliar Faces

Second-order visual filters are the mechanisms which preattentively combine the rectified outputs of first-order filters (the linear striate neurons). This allows them to select the image areas which are characterized by spatial heterogeneity of the local visual features. The aim of our research is to determine whether information from these areas may be sufficient to detect unfamiliar faces and to distinguish their gender. In our experiments we used digital photos of real living things or artificial objects and faces. All these images were adjusted to an average luminance, contrast and size (7 angle degree) and were processed to extract the areas which differ the most in contrast, orientation, and spatial frequency in each of the six spatial frequencies (0.5, 1, 2, 4, 8, and 16 cpd). The other image parts were adjusted to the background. The obtained pictures were presented in a random sequence. The observer had to say what he/she saw after each presentation. When a face was presented the observer’s answer could be assigned to one of the categories: ‘it is not clear’, ‘head’, ‘human face’, ‘male / female’. We found that the information contained in the image areas with a spatial heterogeneity of the local features is sufficient not only for detecting a face, but also for distinguishing its gender. The best results were obtained at a carrier frequency of 2 cpd. The results were a little bit worse at 0.5 and 1 cpd. However, the information extracted from the high-frequency half of the spectrum was significantly less useful. The obtained results allow us to suggest that the information transmitted by the second-order visual filters may be used for pattern recognition.

scholarly journals Different latencies of edge detection cause the fluttering-heart illusion

2021 ◽  
Author(s):  
Masahiro Suzuki ◽  
Kazuhisa Yanaka
Keyword(s):  
Edge Detection ◽  
Luminance Contrast ◽  
Second Order ◽  
High Luminance ◽  
First Order ◽  
Low Luminance

AbstractWe studied the mechanism causing the fluttering-heart illusion in which the motion of an inner figure appears unsynchronized compared with that of the outer figure surrounding it although the motion of both figures is objectively synchronized in reality. Experiment 1 examined the effect of edges’ luminance contrasts. The illusion was measured under conditions where the luminance contrasts of the outer and inner figures’ edges were varied. The results indicated that the illusion occurred when the outer figure’s edge had a high luminance contrast and the inner figure’s edge had a low luminance contrast and that the illusion was reversed when the outer figure’s edge had a low luminance contrast and the inner figure’s edge had a high luminance contrast. Experiment 2 examined the effect of the first- and second-order edges. The illusion was measured under conditions where the first- and second-order edges coexisted or only the first-order edges existed. The results indicated that the illusion occurred when the outer figure had the first-order edge and the inner figure had the second-order edge, and that the illusion was reversed when the outer figure had the second-order edge and the inner figure had the first-order edge. These findings supported the hypothesis that the different latencies of edge detection cause the fluttering-heart illusion.

scholarly journals Interaction between the forced and parametric excitations with different degrees of smallness

1998 ◽  
Vol 20 (2) ◽  
pp. 11-17
Author(s):  
Nguyen Van Dao
Keyword(s):  
Nonlinear System ◽  
Parametric Excitation ◽  
Asymptotic Method ◽  
Special Interest ◽  
Second Order ◽  
First Order ◽  
First Approximation ◽  
Forced Excitation

The nonlinear system under consideration in this paper has a specification which can be stated as an interaction between the first order of smallness no resonance parametric excitation and the second order of smallness resonance forced excitation. In the first approximation these excitations have no effect. However, they do interact one with another in the second approximation.The equations for the amplitude and phase of oscillation are found by means of the asymptotic method. The stationary oscillations and their stability are of special interest.

Disappearance Voltage Determinations Using a Convergent Beam

1971 ◽  
Vol 29 ◽  
pp. 184-185
Author(s):  
W. L. Bell
Keyword(s):  
Second Order ◽  
Objective Method ◽  
Uniform Thickness ◽  
Rocking Curve ◽  
Crystal Perfection ◽  
Kikuchi Line ◽  
Central Maximum ◽  
Diffraction Patterns ◽  
Convergent Beam ◽  
Beam Technique

Disappearance voltages for second order reflections can be determined experimentally in a variety of ways. The more subjective methods, such as Kikuchi line disappearance and bend contour imaging, involve comparing a series of diffraction patterns or micrographs taken at intervals throughout the disappearance range and selecting that voltage which gives the strongest disappearance effect. The estimated accuracies of these methods are both to within 10 kV, or about 2-4%, of the true disappearance voltage, which is quite sufficient for using these voltages in further calculations. However, it is the necessity of determining this information by comparisons of exposed plates rather than while operating the microscope that detracts from the immediate usefulness of these methods if there is reason to perform experiments at an unknown disappearance voltage.The convergent beam technique for determining the disappearance voltage has been found to be a highly objective method when it is applicable, i.e. when reasonable crystal perfection exists and an area of uniform thickness can be found. The criterion for determining this voltage is that the central maximum disappear from the rocking curve for the second order spot.

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