Merrielle Spain

Tunable Color Filters Based on Metal-Insulator-Metal Resonators

Kenneth Diest, Jennifer A. Dionne, Merrielle Spain, and Harry A. Atwater

We report a method for filtering white light into individual colors using metal-insulator-metal resonators. The resonators are designed to support photonic modes at visible frequencies, and dispersion relations are developed for realistic experimental configurations. Experimental results indicate that passive Ag/Si₃N₄/Au resonators exhibit color filtering across the entire visible spectrum. Full field electromagnetic simulations were performed on active resonators for which the resonator length was varied from 1-3 µ m and the output slit depth was systematically varied throughout the thickness of the dielectric layer. These resonators are shown to filter colors based on interference between the optical modes within the dielectric layer. By careful design of the output coupling, the resonator can selectively couple to intensity maxima of different photonic modes and, as a result, preferentially select any of the primary colors. We also illustrate how refractive index modulation in metal-insulator-metal resonators can yield actively tunable color filters. Simulations using lithium niobate as the dielectric layer and the top and bottom Ag layers as electrodes, indicate that the output color can be tuned over the visible spectrum with an applied field. [PDF|BibTeX]

@article{diestEt09,
	Author = {Kenneth Diest and Jennifer A. Dionne and Merrielle Spain and Harry A. Atwater},
	Journal = {Nano Letters},
	Title = {Tunable Color Filters Based on Metal-Insulator-Metal Resonators},
	Year = {2009}}

Some objects are more equal than others: measuring and predicting importance

Merrielle Spain and Pietro Perona

We observe that everyday images contain dozens of objects, and that humans, in describing these images, give different priority to these objects. We argue that a goal of visual recognition is, therefore, not only to detect and classify objects but also to associate with each a level of priority which we call importance. We propose a definition of importance and show how this may be estimated reliably from data harvested from human observers. We conclude by showing that a first-order estimate of importance may be computed from a number of simple image region measurements and does not require access to image meaning. [PDF|BibTeX]

@inproceedings{spainPerona08,
    Author = {Merrielle Spain and Pietro Perona},
    Booktitle = {Proceedings of the European Conference on Computer Vision ({ECCV})},
    Title = {Some objects are more equal than others: measuring and predicting importance},
    Year = {2008}}

Objects predict fixations better than early saliency

Wolfgang Einhauser*, Merrielle Spain*, and Pietro Perona

Humans move their eyes while looking at scenes and pictures. Eye movements correlate with shifts in attention and are thought to be a consequence of optimal resource allocation for high-level tasks such as visual recognition. Models of attention, such as "saliency maps", are often built on the assumption that "early" features (color, contrast, orientation, motion and so forth) drive attention directly. We explore an alternative hypothesis: observers attend to "interesting" objects. To test this hypothesis, we measure the eye-position of human observers while they inspect photographs of common natural scenes. Weighted with recall frequency, named objects predict fixations in individual images better than early saliency. This suggests that early saliency has only an indirect effect on attention, acting through recognized objects. Consequently, rather than treating attention as mere preprocessing step for object recognition, models of both need to be integrated. [PDF|BibTeX]

@article{einhauserSpainPerona08,
	Author = {Wolfgang Einhauser and Merrielle Spain and Pietro Perona},
	Date-Modified = {2008-11-21 18:32:47 -0800},
	Journal = {Journal of Vision},
	Number = {14},
	Pages = {1-26},
	Title = {Objects predict fixations better than early saliency},
	Url = {http://journalofvision.org/8/14/18/},
	Volume = {8},
	Year = {2008}}