Automated detection of the left ventricular region of interest by means of the extraction of typical behaviors in cardiac radionuclide angiographies.

An automated process for the detection of the left ventricular end diastolic contour is defined. The extraction of a pure left ventricular behavior, obtained by the application of the Gram-Schmidt orthogonalization process on a set of vectors representing the three main typical behaviors present in the scintigraphic sequence, yields the synthesis of a new factorial image particularly matched for the extraction of the left ventricular region of interest (ROI). An edge following technique with conditional dilation applied simultaneously on the two binary images resulting from processing the new left ventricular factorial and the average images with a Laplacian operator gives a robust method for the detection of the left ventricular ROI.

Optical statistical classifiers using coherent and incoherent light.

Breast thermograms are digitally classified by means of a principal component analysis of a training set of breast spectral differences obtained in coherent light. The results are compared to the usual partition in categories of medical diagnosis. The statistical operators initiating the classification being expressed in terms of spatial frequencies, the thermograms can be optically classified by using optical representations of the operators that play the role of filters. In coherent light one deals with a conventional spatial frequency filtering, and in incoherent light the thermograms are processed by imaging through suitable coding pupils. In both cases the principal components are easily computed from the measurement of luminous intensities. Such analog computers are expected to increase the throughput of processed images by avoiding needless digitization.

Processing optical data matrices.

The cross-correlation matrix of a set of signals is obtained by multiple Fourier holography. Various sources of error make this kind of matrix not directly interpretable. Global methods that correct deterministic fluctuations as well as random perturbations are proposed. They do not take into account any individual element of the matrix, but they minimize the over-all variance. The efficiency of these methods is illustrated by the example of the classification of sonagrams.

Optical pattern recognition and clustering: Karhunen-Loève analysis.

A Fourier transform gives a first dimensionally reduced description of optical data. But it is not sensitive to statistical variations characterizing class properties and allowing clustering and statistical recognition. A Karhunen-Loève transform of Fourier spectra leads to a more classifying space: it is shown, through examples of writings, that clustering of optical data (especially recognition of scriptors) is achieved in a 2-D Karhunen-Loève space. Inner evolution of data belonging to a given class is described in a 3-D KL space, allowing the dating of texts.

Circular-Fourier-radial-Mellin transform descriptors for pattern recognition.

Image descriptors based on a circular-Fourier-radial-Mellin transform are proposed. They are invariant with respect to rotation, translation, and change of scale. They represent a generalized approach to specific descriptors using a circular-harmonic expansion, a Mellin transform, or moment invariants. The possibility of computing the Fourier-Mellin descriptors by using an optical processor in real time is discussed.

Effective optical processor for computing image moments at TV rate: use in handwriting recognition.

An incoherent multiplexed optical processor is described that computes in real time the moments of images sensed by a TV camera and displayed on a monitor. The first ten moments are generated in parallel and are detected by a photodetector array. They are collected by a microcomputer for subsequent pattern recognition use. Calibration and resolution problems are discussed with regard to the effective 2% system accuracy. Its use in real-time processing of one hundred handwritten pages shows the processor to be a practical moment generator.

Processing measurements of the directional content of Fourier spectra.

Directional analysis and filtering make use of the most straightforward properties of optical Fourier transforms. A quantitative study of the detectability of angular maximums in Fourier spectra and its relationships with the shape and distribution of elements in the object is proposed. The problem is modeled by using a simple object which consists of the superimposition of two random distributions of rectangular grains, one being rotated with respect to the other. Computing the Fourier spectrum of this object allows the expression of the amount of light integrated through a wedge which scans the spectrum. An index of angular separability of the two distributions is made up from such measurements. It is shown to depend on the rotation angle as well as the grain shape. Using an additional spatial filter can improve this index. The influence of its radius is studied. Experimental results obtained either in real time with optical fibers or on photographic records with a microdensitometer are compared with the theoretical ones. They show the necessity of the implementation of optimal estimation schemes to reduce the influence of the noise. Two linear least squares filters are used: an angular Wiener filter and an autoregressive one. In the case of a high signal-to-noise ratio, the Wiener filter reduces to a Laplacian filter which does not depend on the shape of the grains.

Statistical spatial filtering: application to aerial photographs.

Spatial filtering is shown to apply not only to the identification of deterministic signals but also to the classification of images. The spectral content of images is put into a classifier that extracts the dominant eigenvectors responsible for statistical features. Principal images that carry most of the information are obtained by using optical representations of eigenvectors as spatial filters. The statistical stability and the intrinsic dimensionality of Fourier spectra are related to the fast estimation of useful eigenvectors.

Optical computing and investigations on writing.

In previous years several methods have been developed for extracting significant information parameters contained in written, typed, or printed texts. They have shown that some models (optical, mathematical, or hybrid) could be described for linear and nonlinear operations. At first, essential features of information contained in a written page are quantitatively specified and related to legibility criteria. Then an approach to handwriting analysis is made through coherent optical processing along two distinct ways: (1) averaging permits assessing a degree of resemblance between any letter in a set and that taken as a reference, (2) as similarities cannot be extracted directly, the introduction of a form function applies to the comparison of printed letters of various types taken as a whole and other kinds of graphic signs. Finally a nonlinear model built up from polynomials can afford a complete analysis of handwriting as illustrated by various examples.

[The effect of a substance extracted from the urine of prepubertal children on circulating rat gonadotropins]. / Action d'une substance extraite de l'urine d'enfant impubère sur les gonadotrophines circulantes du rat

In the male rat, castration causes an increase of the LH level measured by radioimmunoassay. The application of a compound extracted from a impuber child urine and having anti-gonadotropic effects revealed biologically cannot stop this increase that is even put up by the treatment.

Scintigraphic image contrast-enhancement techniques: global and local area histogram equalization.

This article develops two contrast-modification techniques for the display of scintigraphic images. Based on histogram-modification techniques, histogram equalization, where each level of gray is used to the same extent, gives maximum entropy. The first technique uses the application of histogram equalization in the whole image. To eliminate contrast attenuation small but important portion of the gray scale histogram, local area histogram equalization has been applied to images with differences in intensity. Both techniques were tested using a phantom with known characteristics. The global equalization technique is more suitable to bone scintigraphies, and some well-chosen boundaries improved the difference between two comparable areas. For liver scintigraphies, where intensity is quite equal in every pixel, a local area equalization was chosen that allowed detection of heterogeneous structures. The images resulting from histogram-equalization techniques improve the readability of data, but are often far from usual images and necessitate an apprenticeship for the physician.

Three methods of information assessment for optical data processing.

The determination of the specific information in a message has proved of interest in coding (for instance in a hologram) as well as in data processing itself. Also, simple considerations about the definition of optical information have grown into several groups of processing methods. At first the concept of characteristic spatial frequency bands, which describe essential features of any object, leads to compression of its Fourier terms in order to increase the transfer density of a transmitting system and the storage capacity of the recording media. With the emphasis being put on the informative value of the reference in holography, geometrical compression is applied in particular to the coding of printed texts. The second and third groups of methods apparently deal with opposite approaches. Assuming a given message, one may select some parts of its spectrum for further processing or carry out average signals from the collections it contains. Both cases-sampling and averaging-permit the extraction of a group of data belonging to a set of discrete signals. The following developments are presented: image replicating at a determined energy level, step-by-step phase sampling grids, study of the displacement law for moving objects by random sampling of disturbed wavefronts and recording of incoherent holograms, on the one hand, and construction of average letters for comparison between manuscripts, average Fourier holograms, and power spectra, on the other hand. A last illustration is provided in connection with the appraisal of psychological tests.

[Adaptation of blood sugar regulation during muscular activity. Effects of training]. / Adaptations de la régulation glycémique au cours de l'activité musculaire. Effets de l'entraînement.

Our aim was to study the adaptation of energetic metabolism to muscular activity and the effects of training upon these adaptations. So we realized swimming and running tests on young healthy adults, selected in "trained" and "untrained". The effects of muscular activity were reflected by a raise of serum F.F.A., clearly noted in "untrained" subjects ; the levels of glucose and growth hormone both raised, but especially in "trained" subjects. Cortisol level raised in varying degrees while insulinemia presented little changes.