Image analysis using enhanced spatial correlation functions

By enhancing the high frequencies of the irradiance spectrum of a scene, it is possible to reconstruct an enhanced self-correlation function that clearly delineates its nondifferentiable regions. The technique has application in image analysis and pattern recognition. By way of example, the enhanced self-correlation function of a certain random process is furnished. Easily discernible are certain periodicities not apparent in the sample functions of the original process.

Use of a diffuser for producing texture masks for image processing

The use of a diffuser in synthesizing binary texture-variance masks for applications in image processing is investigated. The binary texture-variance masks are used to separate various objects in an image on the basis of their spatial texture variance. The diffuser is required to reduce the speckling present in the mask. The reduction in speckling is described quantitatively as a reduction of the misclassification probability associated with the separation of the objects into several texture classes. General results are furnished for the statistics of the field scattered by the diffuser, and these are used to obtain expressions for the misclassification probabilities in the presence of a diffuser. Some applications are furnished.

Value of routine electron microscopy in the differential diagnosis of the nephrotic syndrome

Routine electron microscopic examination of renal biopsies was performed in 37 nephrotic patients with primary glomerular lesions. These cases were classified according to the following pathological patterns: lipoid nephrosis (‘minimal change’, 17 cases), membranous nephropathy (12 cases), focal glomerular sclerosis (1 case), proliferative glomerulonephritis (5 cases), chronic glomerulonephritis (1 case), and ‘unclassified glomerulonephritis’ (1 case). 23 of the presented cases had been diagnosed as lipoid nephrosis by light microscopy. The electron microscopic study confirmed this diagnosis in only 17 cases, demonstrating an early stage of membranous nephropathy in four cases, focal glomerular sclerosis in one case and ‘unclassified glomerulonephritis’ in one case. Brief clinical data of the patients are presented and related to the morphologic findings. The various glomerular lesions causing a nephrotic syndrome in which electron microscopy may aid in attaining a correct diagnosis are summarized and the therapeutic and prognostic importance of accurate diagnosis is stressed.

Some new techniques for processing remotely obtained images by self-generated spectral masks

An extension of a new technique that enables parallel, simultaneous processing of remotely obtained images is presented. The technique holds out promise for automatic on-board classification of data. The central feature involves the generation of binary masks, directly from the image, based on object reflectance data, that groups objects into equivalence classes. These masks, called equivalence class masks, can be used in various logical combinations to isolate classes of objects with a priori known reflectance or radiance signatures. Experimental verification of the technique is furnished for simple scenes. A computational scheme, based on a sequence of integrated irradiance measurements on the image, that enables the identification of objects within an equivalence class is suggested.

Variance measurements by a coherent optical method, with application to image processing

A procedure for measuring the point-to-point local variance of a spatial random scene is discussed. The relations that are required between the second-order statistics of the random process and the parameters of the optical configuration to furnish accurate and stable variance estimates are established. The procedure is experimentally verified by using calibrated samples of the random checkerboard and the overlapping circular grain models. A modification of the procedure enables the generation of spatial masks that are useful in automatic image processing. The spatial masks are used as binary spatial gates to isolate certain classes of objects within a scene and reject all others. Typical masks are synthesized and their applications illustrated.

Diffuse ultrastructural glomerular alterations in apparent 'focal' Schönlein-Henoch nephritis

The ultrastructural features of Schönlein-Henoch nephritis in a 6-year-old child are described. The electron-microscopic study revealed diffuse glomerular involvement consisting of a focal nodular thickening and splitting of the glomerular basement membrane, subendothelial electron-dense deposits in the axial portions of the capillary loops and swelling and reticulation of the endothelial cell cytoplasm. These findings demonstrate that in this case, the nephritis involved all glomeruli, although the light microscopy revealed only focal and segmental lesion.

Optical processing of radar signals with fresnel diffraction masks

A simple real-time coherent optical processor is investigated. The processor uses a filter mask upon which is recorded the Fresnel field of the signal replica. Target range-Doppler information is obtained by observing the time and position of the output. A distinguishing feature of the processor is that for the ordinary PCW pulse, these output quantities are correlated, albeit weakly, in much the same fashion as the range-Doppler estimates associated with the output of the linear FM correlator. This interesting property is shown to depend on a single optical parameter. A modified optical configuration that enables a greater practical exploitation of this property is suggested. To obtain unbiased target range estimates, two output terms must be observed, but the range estimate thus obtained has a lower variance than the estimate obtained from either output.

Some film-noise measurements by diffraction of coherent light

It is known that the diffraction of coherent light can be used for various spatial-noise measurements including the power-spectrum estimation of photographic emulsions. A number of such measurements are presented. The power spectrum of grain noise is compared with several theoretical models. The spectra of grain and phase noise for overexposed film are obtained. A simple procedure for obtaining the variance of the phase noise of photographic film, assuming gaussian statistics and statistical independence between grain and phase noise, is furnished.

Design considerations in power spectra measurements by diffraction of coherent light

The estimation of the spectral density of a spatial random process by diffraction requires that the parameters of the diffraction system be compatible with the statistical properties of the process. Otherwise, the estimate of the spectrum can be unstable or unduly biased. The relation between the second-order statistics of the process and the parameters of a basic diffraction system that are required for reasonable spectral estimates is investigated. Such parameters include aperture dimensions, wavelength, focal length of the lens, and scanning slit size. With the typical diffraction system, it is difficult to estimate the power spectrum because of the presence of the zero-order aperture-diffracted light. A technique is furnished in this paper for spectral estimation at dc. Experimental results are furnished for film grain and total film noise. It is shown that the residual phase noise of film at dc even under so-called matched conditions is large enough to prevent the accurate estimation of the dc value of grain noise.

Some theoretical aspects of high resolution xerographic development

The distribution of toner on the surface of a xerographic plate for an arbitrary one-dimensional periodic charge pattern is considered. Development is taken to be complete, by which it is meant that the electrostatic fields vanish outside the toner already deposited on the surface. The toner is assumed to be a continuous nonconducting medium with a uniform charge density per unit volume. Simultaneous algebraic transcendental equations are formulated for the field-free surface bounding the toner. Examples are given for certain important cases, and the effects of relevant parameters of the system are discussed.