Visuelle Wahrnehmung

Quiz Fragen zu der Vorlesung

Quiz Fragen zu der Vorlesung


L. M.
This flashcard set delves into the intricate world of visual perception at a university level, focusing on object recognition, color theory, and the underlying models and systems that govern how we interpret visual stimuli. It explores various theories and models, such as the HMO model, recognition-by-components, and view-based models, highlighting their strengths and limitations. The flashcards are particularly useful for students and researchers in computer science and cognitive psychology, offering insights into how the human visual system processes and recognizes objects, scenes, and colors, and how these processes can be replicated or understood through computational models.
Cartes-fiches
151
Utilisateurs
2
Langue
Anglais
Catégorie
Informatique
Niveau
Université
Créé / Mis à jour
01.11.2017 / 27.01.2018

Cartes-fiches

10: Which of the following is not a type of cone?

10: What type of lighting conditions occurs during the daytime in full sunlight?

10: In the hue cancellation experiments described in the textbook, if starting colour were too reddish, you would add

10: Which of the following colours is "illegal" for our visual systems?

10: --- are different mixtures of wavelengths that look identical

10: What is the term for the light that illuminates a surface?

10: Name the three steps in colour perception as discussed in the textbook, and briefly describe each one

The three steps are detection, during which wavelengths must be sensed by the photoreceptors, discrimination, during which different wavelengths and combinations of wavelengths are differentiated from each other, and appearance, during which colours are intelligently assigned to objects in the world based on both their sensed colour and scene layout.

10: What kind of lighting conditions are depicted in the photograph?

(gräulich, See, Berge, Mondschein)

10: The principle of univariance refers to the fact that

10: A unique blue is a blue that has no --- or green tint

10: Which of the following is not a unique hue?

10: Which of the following is a typical argument from the textbook about the usefulness of colour vision?

10: What is an afterimage and what does it reveal about how colour perception works?

An afterimage is the continued sensory experience of a stimulus after the stimulus is no longer being viewed. Due to colour neurons fatiguing (or, more accurately, habituating), the afterimage takes on the opposite colour of the inducing stimulus, thereby demonstrating that colour perception involves opponent pairs of colours (red vs. green, blue vs. yellow, and white vs. black).

10: What is a unique hue?

A unique hue is either red, green, blue, or yellow and contains no elements of any other colour. For example, a unique yellow is one that contains no red or green in it, a unique green is one that contains no blue or yellow, and so on. Unique hues are determined through colour cancellation experiments in which, for example, some red is added to a greenish-blue light to cancel out the green and leave only blue. The ability to cancel out red, green, yellow, or blue from a hue demonstrates the existence of colour-opponent mechanisms.

10: What is colour constancy and how does the visual system achieve it?

Colour constancy is the tendency of surfaces to appear to be the same colour under a wide range of illumination conditions, despite the fact that the spectral reflectance function of the surface changes dramatically under different light sources. Colour constancy allows for a stability of perceptual experience across different lighting situations. The visual system achieves colour constancy by taking the illuminant (light source) into account when determining the final appearance of colours. Essentially, the spectral power distribution of a scene is registered by the visual system and subtracted away from the final percept to yield perceptions of colour that are stable across vast changes in the illuminant.

10: What is the difference between additive and subtractive colour mixing?

Additive colour mixing involves combinations of light, while subtractive colour mixing (usually) involves mixtures of pigments. In additive colour mixing, the parts of the visible spectrum contained in each coloured light are combined, while in subtractive colour mixing, the parts of the visible spectrum that are absorbed in each colour pigment are combined.

10: What is the principle of univariance and what are the implications of the principle for colour perception?

The principle of univariance refers to the fact that a single photoreceptor cannot make colour discriminations based on wavelength because an infinite number of wavelength-intensity combinations can elicit the same response from that photoreceptor. There are several implications of the principle, including the idea that at least two photoreceptor types (i.e., photoreceptors that respond to different wavelengths of light) are necessary to perceive colour, and also that in scotopic conditions during which vision is dominated by rods, we perceive little colour in the world because we only have a single type of photoreceptor that is active.

9: Thorpe, Fize & Merlot published a study in ature which exerted a very strong influence on the object recognition community.

In their paper they showed that --- could decide wther a previously unseen --- of a natural scene contained an animal or not.

9: Thorpe, Fize & Merlot published a study in ature which exerted a very strong influence on the object recognition community.

The median reaction time (RT) of the observers was around --- ms with a mean percentage correct of --- % correct (note that the observers showed --- speed-accuracy trade-off).

9: Thorpe, Fize & Merlot published a study in ature which exerted a very strong influence on the object recognition community.

Subsequent --- analyses showed that roughly --- after stimulus onset the measured neurophysiological correlate could already reliable signal the presence or absence of an animal in a post-hoc analysis.

Thus processing of the natural scene stimulus was already completed after such a comparatively short time. 

9: Thorpe, Fize & Merlot published a study in Nature which exerted a very strong influence on the object recognition community.

According to the autors this result provides strong evidence in favour of essentially --- theories in visual object recognition.

9: Thorpe, Fize & Merlot published a study in Nature which exerted a very strong influence on the object recognition community.

 

This, in turn, argues against object recognition theories requiring an explicit  --- step prior to recognition, as such a step is presumed to require  --- --- algorithms.

9: Torralba and Oliva published a paper entitled "Statistics of natural image categories".

They report that, contrary to what was believed before, the --- of (images of) natural scenes is only --- if averaged across image categories, but if analysed separately for different image categories, they found strong correlations between --- of the power spectrum and image categories.

9: Torralba and Oliva published a paper entitled "Statistics of natural image categories".

 

Typically a density-plot the power spectrum of an image of a man-made scene is more ---.

9: Torralba and Oliva published a paper entitled "Statistics of natural image categories".

Based on --- component(s) of a principal component analysis (PCA) performed on the power spectrum, Torralba &Oliva were able to correctly categorise images into animal and non-animal scenes in --- of the cases.

9: Torralba and Oliva published a paper entitled "Statistics of natural image categories".

Calculating the PCA of the power spectrum is a --- operation.

9: Torralba and Oliva published a paper entitled "Statistics of natural image categories".

--- this operation could be performed --- in the human brain given what is currently known about psychiology.

9: Torralba and Oliva published a paper entitled "Statistics of natural image categories".

Thus Torralba & Oliva concluded that animal versus non-animal categorizatioin is so rapid because their --- approach does not require an explicit --- step

9: Wichmann, Drewes, Rosas and Gegenfurtner published a paper --- the conclusion made by Torralba & Oliva.

9: Wichmann, Drewes, Rosas and Gegenfurtner published a paper  casting doubt on the conclusions made by Torralba & Oliva.

The two main conclusions of the study – based on --- – were, first, that for human observer animal detection in typical photographs of natural scenes   --- . 

9: Wichmann, Drewes, Rosas and Gegenfurtner published a paper  casting doubt on the conclusions made by Torralba & Oliva. 

Second, they may indicate that in typical, commercial databases the statistics of the images may --- natural as/than often presumed, because photographs typically represent a --- view of the world.

9: --- describes the structure of a scene without reference to the identity of specific objects in the scene.

9: What are ensemble statistics?

Ensemble statistics are rapidly extracted representations of visual scenes that include the average and distribution of properties like orientation or color over a set of objects or a region of space. Ensemble statistics represent knowledge about the properties of a group of objects rather than individual objects themselves.

9: What are the two pathways to scene perception?

There is both a selective and nonselective pathway for scene perception. The selective pathway involves the allocation of attention to one or a few objects at a time and is governed by the attentional bottleneck. Thus, there is selective processing of objects in the selective pathway, meaning that it is responsible for visual search, binding, and the existence of phenomena such as the attentional blink, change blindness, and inattentional blindness. The nonselective pathway, on the other hand, processes visual scenes holistically, encoding scene gist, spatial layout, and ensemble statistics very quickly. The representations in the nonselective pathway are generated as a whole and do not include descriptions of individual objects within the scene. The nonselective pathway has connections with the selective pathway and can, for instance, guide visual search for particular objects in a scene by helping the observer restrict attention to particular locations in the scene.

5: --- is a mathematical procedure by which a signal can be seperated into comonent sine waves at different frequencies. Combining these sine waves will reproduce the original signal.

Fourir analysis

5: In --- Campbell and Robson published their seminal paper entitled ---

1968

Application of Fourir Analysis to the Visibility of Gratings

5: Given is a sine wave,  g_sine(x) = sin[ω_0 x], as a function of x with fundamental frequency f_0 — and thus ω_0 = 2π f_0 — and unit amplitude. Which of the following equations correctly expresses the Fourier series of a rectangular wave g_sq (x) with the same fundamental frequency and the same unit amplitude?

5: The graph shows the teo central figures from Campbell & Robson (Fig. 3, p.556). 

What is plotted for the open symbols are --- on the y-axis against ---

contrast sensitivities (1 over detection threshold)

spatial frequency in cpd

5: The graph shows the teo central figures from Campbell & Robson (Fig. 3, p.556). 

The open squares show the data for the ---, the open circles for the ---.

square-wave grating

sine-wave grating

5: The graph shows the teo central figures from Campbell & Robson (Fig. 3, p.556). 

The filled black circles show rhe ratio of the --- ---.

square-to-sine

sensitivities

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