spatialfrequencyprocessing is an essential technology for extracting morphological information from an optical image. Although various Fourier-based flat optical elements have been proposed as spatial-frequency filt...
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spatialfrequencyprocessing is an essential technology for extracting morphological information from an optical image. Although various Fourier-based flat optical elements have been proposed as spatial-frequency filters to realize image processing, their transfer functions are statically fixed once fabricated, thus limiting the versatile, dynamic functionalities and practical applications. Here, a novel practical tuning strategy is demonstrated to realize switchable spatial-frequency processing for edge-enhanced and bright-field imaging by employing a tunable hydrogel-scalable nanoslide. By utilizing multilayered metallic and hydrogel stacks construction, the nanoslide directly manipulates the optical spatialfrequency in the wavevector domain and exhibits opposite image processing at different wavelength channels due to the cavity-induced wavelength-sensitivity. More intriguingly, via controlling the ambient humidity, the angular-dependent optical response of the nanoslide can be effectively tuned for dynamic edge-enhanced imaging due to the hydrogel's inflation from moisture. In addition, the nanoslide is readily fabricated at a large scale and integrated into compact imaging systems, such as a biomicroscope. With the advantages of a high numerical aperture approximate to 0.8, polarization-insensitive, microscopy-compatible, and facile architecture, the proposed hydrogel-based nanoslide can find potential applications in machine vision, real-time image processing, biological imaging, and analog computing.
The present study tested the hypothesis that nondominant-eye influences on lateral geniculate nucleus (LGN) neurons affect the processing of spatial and contrast information from the dominant eye. To do this, we deter...
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The present study tested the hypothesis that nondominant-eye influences on lateral geniculate nucleus (LGN) neurons affect the processing of spatial and contrast information from the dominant eye. To do this, we determined the effects of stimulating the nondominant eye at its optimal spatialfrequency on the responses of LGN cells to sine-wave gratings of different spatialfrequency and contrast presented to the dominant eye. Detailed testing was carried out on 49 cells that had statistically significant responses to stimulation of the nondominant eye alone. spatial-frequency response functions to nondominant-eye stimulation indicated that the responses were spatially tuned, as reported previously (Guido et al., 1989). Optimal spatial frequencies through the nondominant eye were significantly correlated with the optimal spatial frequencies through the dominant eve (r = 0.54;P < 0.0001), and the optimal spatial frequencies were fairly similar for the two eyes. Nondominant-eye stimulation changed the maximal amplitude of the fundamental (F1) response to dominant-eye stimulation for only about 45% (22 of 49) of the cells that responded to nondominant-eye stimulation alone. The response vs. contrast function through the dominant eye was altered for 73% of the cells (51% independent of spatialfrequency). Three types of effects were observed: a change in the initial slope of the response vs. contrast function (contrast gain), a change in the response amplitude at which saturation occurred, or an overall change in response at all contrasts. The incidence of these changes was similar for X and Y cells in LGN layers A, A1, and C (only four W cells were tested). Nondominant-eye stimulation had little or no effect on the sizes or sensitivities of the receptive-field centers or surrounds for the dominant eye. In addition, nondominant-eve stimulation had little or no effect on optimal spatialfrequency, spatial resolution, or the bandwidth of spatial-frequency contrast sensitiv
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