The image space of the reconstructed image from the hologram displayed on a digital micromirror device (DMD) is defined by the diffraction pattern induced by the 2D pixel pattern of the DMD, which works as a 2D blazed grating. Within this space, a reconstructed image of is spatially multiplexed by a DMD array that is aligned on a board, without using any extra optics. Each DMD chip reconstructs an image piece of the size . The reconstructed image looks somewhat noisy but regenerates the original object image faithfully.
Digital micromirror device’s (DMD) properties as being a display device for holographic displays are investigated. High speed, a large separation between reconstructed image and reconstruction beam, two symmetric diffraction patterns, and low intensity (0,0)th-order beam at a blazed grating condition are the desired properties for the displays. The blazed grating condition of a DMD can reconstruct images with higher diffraction efficiency than the line grating condition. DMD’s high speed enables to present colors and gray levels to the reconstructed image. However, reconstructed images from a gray-level computer-generated hologram (CGH) and its binary form hologram reveal no noticeable difference between them, except the background noise in the image from the CGH.
A floating image type holographic display which projects an electronically generated holographic image together with a background image displayed on a monitor/TV to enhance the visual effects of the former image is introduced. This display can display a holographic image with a spatial volume floating in the front space of the display with use of PDLC sheets as the focused plane of the image. This display can preserve and enhance the main property of holographic image from a display chip, i.e., a spatial image with a volume. This property had not been appealed by the previous holographic displays due to the much brighter active surface image accompanied with the reconstructed image and the diffuser used for viewing the image.
A solution for describing both the multiview image set, obtained with a parallel camera layout, and the perceived image in a projection-type full parallax multiview imaging system with a parallel projector layout, is derived. This is done with the use of 4times4 homogenous matrices to quantitatively analyze the image quality in the system. The solution provides a means of finding properties and/or behavior of the perceived image changes depending on the viewer's position in the system. The solution can analytically describe the appearance of three-dimensional images in the space generated by the multiview image set displayed on a projection screen
This paper addresses concealed object detection by passive millimeter wave (MMW) imaging. Passive MMW imaging penetrates into clothing to capture metal and man-made objects. In this paper, we propose a multi-level expectation maximization (EM) method to separate the concealed object from the body area. The performance is evaluated by the average probability of error. We will show that the proposed EM processes segments the object area more accurately than the conventional EM method.
Hyperspectral images in the spectral wavelength range of 500 nm to 650 nm are used to detect green mold pathogens, which are parasitic on the surface of lemons. The images reveal that the spectral range of 500 nm to 560 nm is appropriate for detecting the early stage of development of the pathogen in the lemon, because the spectral intensity is proportional to the infection degree. Within the range, it was found that the dominant spectral wavelengths of the fresh lemon and the green mold pathogen are 580 nm and 550 nm, respectively, with the 550 nm being the most sensitive in detecting the pathogen with spectral imaging. The spectral intensity ratio of the infected lemon to the fresh one in the spectral range of 500 nm to 560 nm increases with the increasing degree of the infection. Therefore, the ratio can be used to effectively estimate the degree of lemons infecting by the green mold pathogens. It also shows that the sudden decrease of the spectral intensity corresponding to the dominant spectral wavelength of the fresh lemon, together with the neighboring spectral wavelengths can be used to classify fresh and contaminated lemons. The spectral intensity ratio of discriminating the fresh lemon from the infected one is calculated as 1.15.