Showing papers on "Digital image correlation published in 1978"
TL;DR: In this paper, the effect of geometric distortion on the local accuracy of the image registration algorithms using cross correlation is presented using a probabilistic model describing images as homogeneous random patterns, expressions for the mean and covariance of the local error vector in terms of image and noise autocorrelation functions, geometric distortion, and reference image area are derived.
Abstract: The effect of geometric distortion on the local accuracy of the image registration algorithms using cross correlation is presented. Using a probabilistic model describing images as homogeneous random patterns, expressions for the mean and covariance of the local error vector in terms of image and noise autocorrelation functions, geometric distortion, and reference image area are derived. The geometric distortions considered are those represented by an affine transformation of image coordinates. It is shown that for a fixed geometric distortion there is an image size (integration area) that minimizes the local error. The optimum area decreases with increasing geometric distortion.
43 citations
TL;DR: In this article, it is shown that multi-level correlation is far superior to polarity correlation, that image data shaping is of great importance, and that the correlation system must be highly adaptive.
28 citations
TL;DR: Results are shown for coherent optical processing by computer-controlled Fourier plane filtering and real-time image correlation, and signal processing systems are described which couple the PROM with an acousto-optic raster recorder to perform spectrum analysis and correlation on radio frequency signals.
Abstract: The PROM is a solid-state, rapidly recyclable, image storage device having a number of applications in image and signal processing. Some of its important characteristics include 1/10-wave optical surface quality, 100-1p/mm three-bar resolution, 10 ergs/cm2 light sensitivity, and image plane contrast of 10 4 :1. One of the unique features of the PROM is that the bias level of stored patterns can be adjusted through application of an external voltage, resulting in image contrast inversion or enhancement. This same operation (baseline subtraction) is used to null the zero order in an optical Fourier transform, achieving a Fourier plane signal-to-noise ratio approaching 106:1. This paper reports on the current status of this device and a number of applications for which it has been tested in several areas of image and signal processing. Results are shown for coherent optical processing by computer-controlled Fourier plane filtering and real-time image correlation, and signal processing systems are described which couple the PROM with an acousto-optic raster recorder to perform spectrum analysis and correlation on radio frequency signals.
22 citations
TL;DR: The authors examine the effect of quantization, in particular, the phase parameter which most influences visual appearance and blur of reconstruction image in the binary Fourier hologram generated by the computer.
Abstract: The studies of coherent optics such as optical spatial filtering, optical Fourier transformation, optical holography and its application techniques are now widespread according as the progress and diffusion of laser. On the other hand, many researchers have proposed the various simulation methods of coherent optics by means of the digital computer in stead of using the optical processing systems. In this paper, first of all the basic ideas and many parameters considered in generating the binary Fourier hologram by the computer are briefly reviewed. The authors examine the effect of quantization, in particular, the phase parameter which most influences visual appearance and blur of reconstruction image. Moreover, the results of the computer simulation are compared with that of the optically reconstructed image.