Showing papers on "Feature detection (computer vision) published in 1975"

Apparatus for image manipulation

Abstract: An image can be represented by an M × N array I(*,*) of image points, where each point I(i,j) over the ranges 0≦i

Method and apparatus for form removal from contour compressed image data

Abstract: An apparatus for removing form (background) information from an image for data compression; and for adding the form information during reconstruction of the image. Each object in an image is compressed by contour following of the exterior and interior borders of the object, and encoded in chain link form. Each object in the image as it is compressed is correlated with the appropriate object in the form image by comparing the encoded objects with the already stored encoded objects of the form. If there is a match, the image object which matches the form is deleted from the compressed image. Since the order in which the objects are encountered is known, it is only necessary to correlate each image object with at most a single form object. The correlation includes comparing the starting points of the contour information, the perimeter of the object (the length of its border chain) and the object area. The comparisons are made within a predetermined acceptable tolerance. If the variable image data overlaps some of the form image data, the object is retained in the compressed image. During reconstruction of the image, the form and image data are combined using a technique similar to logical OR operation.

On the cepstrum of two-dimensional functions (Corresp.)

Abstract: Cepstral analysis has been used in speech processing for some time, but in the field of image processing very little attention has been paid to it. Some properties of the two-dimensional cepstrum (especially those absent in the one-dimensional) appear to make it an important tool in image processing. In this correspondence these properties are summarized. Applications to image deblurring (blur identifying) and image classification are mentioned as some possible uses.

Image enhancement method and apparatus

Abstract: Combined optical and electronic apparatus provide for various types of image enhancement by producing two images of the same scene which differ by a predetermined property, and by electronically subtracting the images to yield a video difference signal which emphasizes or deemphasizes a predetermined characteristic of the scene at which the apparatus is pointed. Various types of image enhancement are obtained by simultaneous scanning of the images produced by two imaging systems in which a relative difference in properties between the images such as deliberate misalignment, optical density difference, image resolution, image magnification or image receptor displacement is introduced to create a particular type of enhancement. The intensities from pairs of scanned spots are subtracted on a point-by-point basis to yield a video difference signal which when displayed provides an image enhanced in a particular manner. Property differences are in general introduced in the aperture plane, at the optics or in the image plane. The subject system can be arranged for edge enhancement, size discrimination, emphasis of lines in a predetermined direction, peripheral image enhancement, and central image or boresite enhancement. This system is particularly useful in clutter rejection for TV-based target tracking systems.

Scan and Display Considerations in Processing Images by Digital Computer

Abstract: An analysis of the effects of finite aperture sizes in the scan and display of images is presented. The scanning aperture results in degrading the sample spectrum; the display results in a failure of the Shannon–Whittaker reconstruction theorem. Both effects can be partially corrected for, so as to give an image that is less degraded by scan and display. An example of correction of an actual image is presented as a demonstration.

A contextual effect in feature detection

Abstract: The question i s addressed of whether the perception of a form i s e x c l u s i v e l y determined by a p r i o r analysis of i t s elements, and two major paradigms are reviewed, v i z . , Gestalt and information processing. Three experiments were c a r r i e d out. Experiment 1 employed a s i g n a l detection task to t e s t the hypothesis that embedding a l i n e segment feature i n a unitary f i g u r a l context would f a c i l i t a t e i t s detection. The contextual e f f e c t found f a l s i f i e d the theory of a one-way causation between analysis of f i g u r a l elements and form perception. Experiment 2 showed that a necessary condition of t h i s context e f f e c t on feature detection i s the three-dimensionality of the unitary context. With bi-hemiretinal stimulus presentation Experiment 3 showed a s i g n i f i c a n t context e f f e c t i n the RVF, but not i n the LVF. Some current paradigms are applied to these r e s u l t s ; i t i s argued concurrently that the explanat i o n of phenomena c a l l e d "perceptual" e n t a i l s the s o l u t i o n of two problems:, that of determining what constitutes such an explanation, and an adequate theory of the e x p e r i e n t i a l aspect of perceptual phenomena. These are addressed i n Appendices A arid B.