Backlit Images Research Articles

A human face profile identification system using 1-D real Fourier descriptors

Over the last twenty years, researchers in the field of human face recognition have tried to answer the question, how can a face be formally described? Each new face recognition system provides a different answer. In this paper, the face profile is represented using a real Fourier descriptor. Outlines of face profiles are extracted from back-lit images captured using a CCIR standard TV camera and frame-grabber. Points on the nose tip and chin are extracted and used to standardise the orientation and scale of the profile. The face curve is sampled uniformly in the vertical direction and transformed from a 2-D to a 1-D representation. After Fourier transformation, a small number of the resulting coefficients are used as a feature vector. This descriptor is insensitive to translation, scale and orientation of the original face profile. Applications to face recognition and reconstruction are illustrated and discussed in the paper.

Monochromatic Backlighting as a Laser-Fusion Diagnostic

The case of an x-ray radiographed (backlit) image of a CH-shell laser-fusion target to be imploded by the Omega Upgrade laser system is studied. The goal is to obtain information on the conditions at peak compression, where the experimental constraints due to target self-emission and required spatial resolution are maximal. Particular attention is devoted to the problem of discriminating against the target self-emission. It is shown that a way to selectively image the target with radiation from a backlight source is to obtain a monochromatic image at a single spectral line emitted by the backlighter. Two experimental configurations are discussed: (a) an x-ray microscope with a flat crystal monochromator, and (b) pinhole imaging in conjunction with a curved crystal monochromator. Useful images are obtained with simple CH-shell targets and without the need for a short-pulse backlighter beam.

47 画像処理法による気泡界面挙動の測定限界

An image processing method on two back-lit images which were taken from directions at right angle each other has been developed to measure bubble interface configurations in tube bubbly flow. The position of the bubble in tube cross section cannot be measured when bubble diameter and the concentration increase and making no pairs of bubbles whose vertical position are the same in two images. This paper presents the result of calculation on limit of diameter and concentration for measurement with the image processing method.

Infrared television pupillometer revised: Bright-pupil illumination and computer automation

A new-generation infrared-television pupillometer is described and related issues are discussed. In order to obtain a back-lit image of the pupil of the eye, and infrared-LED illuminator that outputs a squeezed beam and a recent CCD camera having enhanced sensitivity in the near-infrared region were incorporated. The infrared-ray exposure to the eye by this method was determined to be quite low and hence a prolonged reconding could be made with safety. The bright-pupil image gives a definite pupil/iris boundary so that more accurate tracing of pupillary movement becomes feasible. In particular, intrinsic responses of the pupil in dim and dark adapted conditions can be measured stably and precisely. Simple, carefully designed, and inexpensive hardware implementation using a microcomputer, as well as a necessary control program for autonomous data acquisition, is presented in detail.