Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 41 for “"Spatial frequencies"”.
-
The plasticity of the human perceptual systems in processing auditory- and spatial-frequencies
… visual stimuli that I used were Gabor patches - spatial patterns that varied sinusoidally in luminance across the image. The visual system is thought to processes spatial patterns through a series of independent channels, each functioning as a band-pass filter centred around a specific …
-
The Venetian blind effect: Contrast disparity modulation in irradiation stereoscopy
… venetian blind effect for a square-wave carrier spatial frequency of 3.14 c/deg and square-wave modulation spatial frequencies of 0.26, 0.39, 0.79, and 1.57 c/deg.</p><p>In Experiment 2 we increased the spatial frequencies. We measured contrast disparity thresholds for the perception of slant for …
-
Manipulating spatial frequency to understand global and local information processing in 7-month-old infants
… filter real life objects of their high and low spatial frequencies. High spatial frequencies provide information about the smaller parts where as low spatial frequencies provide information about the larger ones. By removing high or low spatial frequency we can control the coarseness of their …
-
The effects of target vibration on the human contrast sensitivity function
… lowers the threshold of detection for low spatial frequencies but raises the threshold for high spatial frequencies. A loss of contrast at high spatial frequencies due to retinal "smear" may be the cause of this increase in high spatial frequency thresholds under vibration. Physiological …
-
Dynamic contrast sensitivity: methods and measurements
… grating slide projections that range in spatial frequency from 0.4 to 20.5 cycles per degree. At each of two different testing sessions, the contrast sensitivities of 60 undergraduate psychology majors were measured at a static, 25 deg/sec, and 50 deg/sec target movement condition. The …
-
Fast Fourier transform square wave voltammetry
… the effect of experimental parameters in the spatial frequency domain. A new method was developed to determine truncation frequencies. A₀, the first spatial frequency, was shown to be an effective measure of peak height and its use in calibration curves was demonstrated. The real and imaginary …
-
Scotopic Vision: Behavioral Sensitivity and Underlying Optical and Neural Factors
… Behavioral sensitivity was measured for 7 spatial frequencies (0, 1/8, 1/4, 1/2, 1, 2 and 4 cyc/deg) using drifting Gabor functions (4 Hz) presented at 8-degree eccentricity along the horizontal meridian. Neural sensitivity was estimated for 3 spatial frequencies (1/8, 2 and 4 cyc/deg) with …
-
Image Evolution Using 2D Power Spectra
… measures from previous studies relate to image spatial frequencies. Based on existing research which uses power spectral density of spatial frequencies as an effective metric for image classification and retrieval, we believe this measure and others based on Fourier decomposition may be …
-
Digital image segmentation using periodic codings
… stages. In each stage, filtering is done in the spatial frequency domain after uniform grating functions are applied to the images in the spatial domain. Then, algorithms for finding the period and phase of a physical grating are explored for a hybrid optical-digital application of the method. …
-
Prediction of modulation detectability thresholds for line-scan displays
… 2 replications at every combination of 10 spatial frequencies, 2 target orientations, and 5 noise amplitudes. Line rates were 525, 945, and 1,225 lines per frame; the spatial frequencies were between 1 and 20 c/deg; and the gratings were oriented vertically (perpendicular to the video …
-
Perception and Eye Alignment Control: Do People Think the Same Way Their Brain Thinks?
… The effect occurs especially for middle and low spatial frequencies. This study compares observers’ stereoscopic depth perception with vertical disparity vergence to understand if this ‘contrast paradox’ affects reflexive eye alignment control. Methods: Four binocular contrast combinations were …
-
An exploration of trypophobia
… images reduced the excess energy at mid-range spatial frequencies (previously associated with both trypophobic and uncomfortable images). Relative to unfiltered trypophobic images, the discomfort from filtered images experienced by observers with high TQ scores was less than that experienced …
-
Computational Analysis of Functional Imaging in the Primary Auditory Cortex
… underlying maps. The experiments suggest that spatial averaging improves the ability to estimate maps with low spatial frequencies or with large amounts of cortical variability, at the cost of decreasing the spatial resolution of the images. Despite the decrease in resolution, the results …
-
Analysis and application of an underwater optical-ranging system
… to determine seafloor roughness for very-high-spatial frequencies (greater than 10 cycles/meter). Use and application recommendations for the system are presented.
-
Contrast Sensitivity to One- and Two-Dimensional Luminance Patterns
… receptive field model combined with watershed spatial vision behavior at spatial frequencies below 1 cycle-per-degree (cpd). The non-significant result for space-averaged luminance was explained by the limited range of manipulation of the variable. Two-dimensional luminance patterns were …
-
A vector model for analysis, decomposition and segmentation of textures
… the use of a priori information of the tonal frequencies present and the tonal amplitude distributions. A proposed algorithm, which uses only a priori knowledge of the spatial frequencies to extract the tonal amplitudes i.e. texture vectors, is discussed. Examp1es illustrating the application …
-
Nanopatterned anchoring layers for liquid crystals
… provide anchoring energy that varies with high spatial frequencies. This thesis describes the use of nano-grooves patterned with electron beam lithography as a novel way to provide varied anchoring energies for Liquid Crystal devices. A Liquid Crystal beam deflector is discussed and designed …
-
Organic materials for holographic applications
… from 1 ms to 100 ms depending on the recording spatial frequencies. Surface anchoring forces play a key role in holographic storage. We investigated these forces with differently treated substrates. Optical surface memory effects are described experimentally. We also seek novel materials for …
-
Aspects of hens’ visual behaviour
… grating patterns of varying contrast and spatial frequency were used to assess the visual resolution of four hens in Experiment 4. Contrast sensitivity functions were measured under two different viewing conditions. These two functions both spanned a range of low spatial frequencies, that …
-
Emotional engagement and orienting: the effects of picture size on affective response
… size is associated with a loss in the low spatial frequencies of a picture, which might confound the interpretation of the results of studies 1-3. Therefore, emotional and neutral images which were either low-pass filtered or reduced in size were presented, and affective responses were …
Page 1 of 3