Two-dimensional random access multiphoton spatial frequency modulated imaging

In this paper, a robust image watermarking method in two-dimensional space/spatial-frequency distributions domain is proposed which is robust against geometric distortion. This watermarking is detected by a linear frequency change. The dopplerlet transformation is used to detect the watermark. The chirp signals are used as watermarks and this type of signals is resistant to all stationary filtering methods and exhibits geometrical symmetry. In the two-dimensional Radon-Wigner transformation domain, the chirp signals used as watermarks change only its position in space/spatial-frequency distribution, after applying linear geometrical attack, such as scale rotation and cropping. But the two-dimensional Radon-Wigner transformation needs too much difficult computing. So the image is put into a series of 1D signal by choosing scalable local time windows. The watermark embedded in the dopplerlet transformation domain. The watermark thus generated is invisible and performs well in StirMark test and is robust to geometrical attacks. Compared with other watermarking algorithms, this algorithm is more robust, especially against geometric distortion, while having excellent frequency properties.

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(Invited) From Field-Effect Transistors to Tunneling Devices and Resistive Random Access Memories in Two-Dimensional Van Der Waals Structures

ECS Meeting Abstracts ◽

10.1149/ma2019-01/12/826 ◽

2019 ◽

Keyword(s):

Field Effect ◽

Field Effect Transistors ◽

Van Der Waals ◽

Random Access ◽

Two Dimensional ◽

Tunneling Devices

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Unrestricted superresolution imaging in scattering tissues with spatial frequency modulated imaging (Conference Presentation)

Single Molecule Spectroscopy and Superresolution Imaging XI ◽

10.1117/12.2290271 ◽

2018 ◽

Author(s):

Jeffrey J. Field ◽

Patrick Stockton ◽

Randy A. Bartels

Keyword(s):

Spatial Frequency ◽

Superresolution Imaging ◽

Modulated Imaging

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Extending the performance of linear and nonlinear spatial frequency modulated imaging platforms (Conference Presentation)

Ultrafast Nonlinear Imaging and Spectroscopy VI ◽

10.1117/12.2321327 ◽

2018 ◽

Author(s):

Jeffrey A. Squier ◽

Nathan Worts ◽

Alyssa Allende Motz ◽

Jeff Field ◽

Keith Wernsing ◽

...

Keyword(s):

Spatial Frequency ◽

Linear And Nonlinear ◽

Modulated Imaging

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Two-Dimensional Spatial Frequency Content and Confusions among Dot Matrix Characters

Proceedings of the Human Factors Society Annual Meeting ◽

10.1177/107118137902300197 ◽

1979 ◽

Vol 23 (1) ◽

pp. 384-388

Author(s):

Michael E. Maddox

Keyword(s):

Spatial Frequency ◽

Similarity Measure ◽

Similarity Measures ◽

Final Analysis ◽

Second Phase ◽

Two Dimensional ◽

Two Phase ◽

Frequency Spectra ◽

Character Size ◽

Point Fast Fourier Transform

A two-phase study was conducted which related the confusions among dot matrix characters to the two-dimensional spatial frequency similarity of these characters. During the first phase of the study, subjects were shown single alphanumeric characters from four different dot matrix fonts and five matrix size/character sub-tense combinations. Data from this phase of the research were analyzed in terms of both correctness and character confusion frequencies. The second phase of the study consisted of digitizing and analyzing all characters from two of the fonts used in the first phase. The fonts chosen represent the most and least confusable of the four, based on the performance data obtained. These characters were scanned photometrically using a computer-controlled X-Y stage and subjected to a 512 × 512 point fast Fourier transform (FFT). The Fourier coefficients were correlated for all possible character pairs within each font-matrix/character size cell. These correlations provided an objective similarity measure among characters based upon their 2-D spatial frequency spectra. In addition to the spatial frequency similarity measure, a simple digital Phi coefficient was calculated for each character pair. The final analysis performed in this study was the correlation of observed performance (confusions) with objective similarity measures (2-D spectra and Phi coefficients).

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