Scene Exploration with Fourier-Filtered Peripheral Information

Perception ◽  
1998 ◽  
Vol 27 (10) ◽  
pp. 1141-1151 ◽  
Author(s):  
Paul M J van Diepen ◽  
Martien Wampers
Keyword(s):  
Spatial Frequency ◽  
Search Task ◽  
High Spatial Frequency ◽  
Decision Task ◽  
Minor Importance ◽  
Initial Part ◽  
Object Search ◽  
Low Pass ◽  
Realistic Scenes ◽  
High Pass

In a previous moving-window study it was found that scene exploration benefits more from peripheral information of high spatial frequency than of low spatial frequency. In the present study, degraded versions of realistic scenes were presented peripherally during the initial 150 ms of fixations, while the undegraded scene was presented foveally. The undegraded version of the scene was visible both foveally and peripherally during the later part of fixations. During the initial 150 ms, the peripheral part of scenes was low-pass, bandpass, or high-pass filtered, blanked, or decreased in luminance. In a no-change condition, the undegraded scene was presented throughout the whole fixation. Participants freely explored the scenes in the context of an object-decision task. It was found that degrading peripheral information during the initial part of fixations had minimal effect on scene exploration. No reliable differences were found among the three filter types. The results indicate that, in the context of an object-search task, peripheral information is of minor importance during the initial part of fixations.

scholarly journals Effects of Spatial Frequency Content on Classification of Face Gender and Expression

2010 ◽  
Vol 13 (2) ◽  
pp. 525-537 ◽  
Author(s):  
Luis Aguado ◽  
Ignacio Serrano-Pedraza ◽  
Sonia Rodríguez ◽  
Francisco J. Román
Keyword(s):  
Spatial Frequency ◽  
Reaction Times ◽  
High Spatial Frequency ◽  
Gender Categorization ◽  
Spatial Frequency Filtering ◽  
Low Pass ◽  
Face Experiment ◽  
Expression Classification ◽  
High Pass

The role of different spatial frequency bands on face gender and expression categorization was studied in three experiments. Accuracy and reaction time were measured for unfiltered, low-pass (cut-off frequency of 1 cycle/deg) and high-pass (cut-off frequency of 3 cycles/deg) filtered faces. Filtered and unfiltered faces were equated in root-mean-squared contrast. For low-pass filtered faces reaction times were higher than unfiltered and high-pass filtered faces in both categorization tasks. In the expression task, these results were obtained with expressive faces presented in isolation (Experiment 1) and also with neutral-expressive dynamic sequences where each expressive face was preceded by a briefly presented neutral version of the same face (Experiment 2). For high-pass filtered faces different effects were observed on gender and expression categorization. While both speed and accuracy of gender categorization were reduced comparing to unfiltered faces, the efficiency of expression classification remained similar. Finally, we found no differences between expressive and non expressive faces in the effects of spatial frequency filtering on gender categorization (Experiment 3). These results show a common role of information from the high spatial frequency band in the categorization of face gender and expression.

The Role of High Spatial Frequencies in Face Perception

Perception ◽  
1983 ◽  
Vol 12 (2) ◽  
pp. 195-201 ◽  
Author(s):  
Adriana Fiorentini ◽  
Lamberto Maffei ◽  
Giulio Sandini
Keyword(s):  
Spatial Frequency ◽  
Face Perception ◽  
Energy Content ◽  
High Spatial Frequency ◽  
Face Width ◽  
Spatial Frequencies ◽  
Low Pass ◽  
High Pass ◽  
Spatial Frequency Domain

The relevance of low and high spatial-frequency information for the recognition of photographs of faces has been investigated by testing recognition of faces that have been either low-pass (LP) or high-pass (HP) filtered in the spatial-frequency domain. The highest resolvable spatial frequency was set at 15 cycles per face width (cycles fw−1). Recognition was much less accurate for images that contained only the low spatial frequencies (up to 5 cycles fw−1) than for images that contained only spatial frequencies higher than 5 cycles fw−1. For faces HP filtered above 8 cycles fw−1, recognition was almost as accurate as for faces LP filtered below 8 cycles fw−1, although the energy content of the latter greatly exceeded that of the former. These findings show that information conveyed by the higher spatial frequencies is not redundant. Rather, it is sufficient by itself to ensure recognition.

The Role of High Spatial Frequencies in Hemispheric Processing of Categorical and Coordinate Spatial Relations

2004 ◽  
Vol 16 (9) ◽  
pp. 1576-1582 ◽  
Author(s):  
Matia Okubo ◽  
Chikashi Michimata
Keyword(s):  
Visual Field ◽  
Spatial Frequency ◽  
Right Hemisphere ◽  
High Spatial Frequency ◽  
Spatial Relation ◽  
Spatial Relations ◽  
Right Visual Field ◽  
Spatial Frequencies ◽  
Low Pass ◽  
Categorical Task

Right-handed participants performed categorical and coordinate spatial relation tasks on stimuli presented either to the left visual field-right hemisphere (LVF-RH) or to the right visual field-left hemisphere (RVF-LH). The stimuli were either unfiltered or low-pass filtered (i.e., devoid of high spatial frequency content). Consistent with previous studies, the unfiltered condition produced a significant RVF-LH advantage for the categorical task and an LVF-RH advantage for the coordinate task. Low-pass filtering eliminated this Task × Visual Field interaction; thus, the RVF-LH advantage disappeared for the categorical task. The present results suggest that processing of high spatial frequency contributes to the left hemispheric advantage for categorical spatial processing.

The Effect of Image Quality on Search for Static and Dynamic Targets: MTFA-Performance Correlations

1979 ◽  
Vol 23 (1) ◽  
pp. 339-343
Author(s):  
James C. Gutmann ◽  
Harry L. Snyder ◽  
Willard W. Farley ◽  
John E. Evans
Keyword(s):  
White Noise ◽  
Performance Measures ◽  
Search Task ◽  
Search Time ◽  
Video Signal ◽  
Modulation Transfer ◽  
Low Pass ◽  
And Performance ◽  
High Pass

This report contains the results of two experiments which investigated the effects of the quality of a televised image on eye movements and search-related measures. The first experimental search task involved having subjects perform an air-to-ground search during a simulated flight. The quality of the image presented was varied by either passing, low-pass filtering, or attenuating the video signal and by adding electrical white noise to the video signal. Low to moderate correlations between modulation transfer function area (MTFA) and performance measures generally indicated that as MTFA increases performance improves and fixation durations decrease. The search task of the second experiment consisted of having the subjects search for a designated letter or numeral across a televised picture of randomly positioned letters and numerals. The quality of the picture was varied by either passing, low-pass filtering, high-pass filtering, or attenuating the video signal and by adding electrical white noise to the video signal. Correlations between MTFA and performance measures indicated that increases in MTFA lead to decreases in search time and decreases in fixation duration.

The Importance of High Spatial Frequencies for Exogenous Consciousness. Evidence from the Attentional Blink Paradigm.

2019 ◽  
Author(s):  
Mickaël Jean Rémi Perrier ◽  
Louise Kauffmann ◽  
Carole Peyrin ◽  
Nicolas Vermeulen ◽  
Frederic Dutheil ◽  
...  
Keyword(s):  
Spatial Frequency ◽  
Visual System ◽  
Attentional Blink ◽  
Crucial Role ◽  
Conscious Perception ◽  
Frequency Content ◽  
Spatial Frequencies ◽  
Low Pass ◽  
Visual Consciousness ◽  
High Pass

We attempted to highlight the respective importance of low spatial frequencies (LSFs) and high spatial frequencies (HSFs) in the emergence of visual consciousness by using an attentional blink paradigm in order to manipulate the conscious report of visual stimuli. Thirty-eight participants were asked to identify and report two targets (happy faces) embedded in a rapid stream of distractors (angry faces). Conscious perception of the second target (T2) usually improved as the lag between the targets increased. The distractors between T1 and T2 were either non-filtered (broad spatial frequencies, BSF), low-pass filtered (LSF), or high-pass filtered (HSF). The spatial frequency content of the distractors resulted in a greater disturbance of T2 reporting in the HSF than in the LSF condition. We argue that this could support the idea of HSF information playing a crucial role in the emergence of exogenous consciousness in the visual system. Other interpretations are also discussed.

Age-related macular degeneration changes the processing of visual scenes in the brain

2018 ◽  
Vol 35 ◽  
Author(s):  
STEPHEN RAMANOËL ◽  
SYLVIE CHOKRON ◽  
RUXANDRA HERA ◽  
LOUISE KAUFFMANN ◽  
CHRISTOPHE CHIQUET ◽  
...  
Keyword(s):  
Spatial Frequency ◽  
Macular Degeneration ◽  
Scene Perception ◽  
High Spatial Frequency ◽  
Age Related Macular Degeneration ◽  
Age Related ◽  
Spatial Frequencies ◽  
Visual Scenes ◽  
High Pass ◽  
Frequency Processing

AbstractIn age-related macular degeneration (AMD), the processing of fine details in a visual scene, based on a high spatial frequency processing, is impaired, while the processing of global shapes, based on a low spatial frequency processing, is relatively well preserved. The present fMRI study aimed to investigate the residual abilities and functional brain changes of spatial frequency processing in visual scenes in AMD patients. AMD patients and normally sighted elderly participants performed a categorization task using large black and white photographs of scenes (indoors vs. outdoors) filtered in low and high spatial frequencies, and nonfiltered. The study also explored the effect of luminance contrast on the processing of high spatial frequencies. The contrast across scenes was either unmodified or equalized using a root-mean-square contrast normalization in order to increase contrast in high-pass filtered scenes. Performance was lower for high-pass filtered scenes than for low-pass and nonfiltered scenes, for both AMD patients and controls. The deficit for processing high spatial frequencies was more pronounced in AMD patients than in controls and was associated with lower activity for patients than controls not only in the occipital areas dedicated to central and peripheral visual fields but also in a distant cerebral region specialized for scene perception, the parahippocampal place area. Increasing the contrast improved the processing of high spatial frequency content and spurred activation of the occipital cortex for AMD patients. These findings may lead to new perspectives for rehabilitation procedures for AMD patients.

Hyper-vision in a patient with central and paracentral vision loss reflects cortical reorganization

2003 ◽  
Vol 20 (5) ◽  
pp. 501-510 ◽  
Author(s):  
CLARA CASCO ◽  
GIANLUCA CAMPANA ◽  
ALBA GRIECO ◽  
SILVANA MUSETTI ◽  
SALVATORE PERRONE
Keyword(s):  
Visual Acuity ◽  
Spatial Frequency ◽  
Vision Loss ◽  
High Spatial Frequency ◽  
Cortical Reorganization ◽  
Decision Task ◽  
Poor Vision ◽  
Visual Tasks ◽  
Behavioral Evidence

SM, a 21-year-old female, presents an extensive central scotoma (30 deg) with dense absolute scotoma (visual acuity = 10/100) in the macular area (10 deg) due to Stargardt's disease. We provide behavioral evidence of cortical plastic reorganization since the patient could perform several visual tasks with her poor-vision eyes better than controls, although high spatial frequency sensitivity and visual acuity are severely impaired. Between 2.5-deg and 12-deg eccentricities, SM presented (1) normal acuity for crowded letters, provided stimulus size is above acuity thresholds for single letters; (2) a two-fold sensitivity increase (d-prime) with respect to controls in a simple search task; and (3) largely above-threshold performance in a lexical decision task carried out randomly by controls. SM's hyper-vision may reflect a long-term sensory gain specific for unimpaired low spatial-frequency mechanisms, which may result from modifications in response properties due to practice-dependent changes in excitatory/inhibitory intracortical connections.

Evidence for the View That Temporospatial Integration in Vision is Temporally Anisotropic

Perception ◽  
1997 ◽  
Vol 26 (9) ◽  
pp. 1169-1180 ◽  
Author(s):  
Denis M Parker ◽  
J Roly Lishman ◽  
Jim Hughes
Keyword(s):  
Spatial Frequency ◽  
Spatial Information ◽  
High Spatial Frequency ◽  
Spatial Frequencies ◽  
Integration Mechanism ◽  
Low Pass ◽  
Degraded Image ◽  
Efficient Integration ◽  
Urban Scene ◽  
Frequency Sequence

In two experiments low-pass and high-pass spatially filtered versions of a base image were prepared and the effect of the order of delivery of sequences of filtered and base images investigated. A task that required subjects to discriminate 120 ms presentations of a full-bandwidth base image and degraded sequences that contained sets of three different spatially filtered versions, or mixtures of spatially filtered and full-bandwidth versions of the image, were used. Each set of images used in the degraded sequences was presented either so that within the 120 ms presentation window the spatial content swept from low to high spatial frequencies or from high to low. In experiment 1 twenty subjects discriminated between a base image and degraded sequences of an urban scene. Results showed both a significant overall effect of image order, with low-to-high spatial-frequency information delivery being mistaken more often for the full-bandwidth presentation than high-to-low, and that different sets of degraded image sequences varied significantly in the frequency with which they were mistaken for the full-bandwidth presentation. In experiment 2 a base and filtered versions of a human face were used in an identical task with twenty different subjects and a very similar pattern of significant results was obtained, although imposed on a lower overall error frequency than that obtained in experiment 1. It was concluded that the results of both experiments provide evidence for an anisotropic temporospatial integration mechanism in which availability of spatial information in a low-to-high spatial-frequency sequence results in more efficient integration than a high-to-low.

Sign in / Sign up

Export Citation Format

Share Document