Showing papers on "Image scaling published in 1990"

Motion compensated image interpolation

Abstract: Field skipping is a variable technique for reducing drastically the bit rate necessary to transmit a television signal. All fields have to be reconstructed at the receiver end, but nearest-neighbor or linear interpolations give poor performances when significant scene activity is present; therefore, some motion compensation scheme is mandatory. Although any of the algorithms proposed for motion estimation can be used for motion compensated interpolation, in this paper only the pel-recursive algorithm is considered. Past experience is briefly summarized and, based on criticism, improvements to the basic algorithm are proposed that seem to lead to an estimated motion field that is accurate enough. Multiple recursions and appropriate selection rules are proposed to counteract streaking effects of the recursive algorithm when it crosses image boundaries. The estimation of a forward and a backward motion field is used to identify image areas where occlusion effects are present. Experimental results are presented that seem to indicate that the proposed interpolation scheme has good performance. >

Digital image interpolator with multiple interpolation algorithms

Abstract: An interpolator for enlarging or reducing a digital image includes an interpolation coefficient memory containing interpolation coefficients representing several different one dimensional interpolation kernels. A row interpolator receives image pixel values, retrieves interpolation coefficients from the memory, and produces interpolated pixel values by interpolating in a row direction. A column interpolator receives multiple rows of interpolated pixel values from the row interpolator, retrieves interpolation coefficients from the memory, and produces rows of interpolated pixel values by interpolating in a column direction. A logic and control unit monitors the content of the input data and switches between interpolation kernels to provide optimum interpolation for each type of content.

Process and device for temporal image interpolation, with corrected movement compensation

Abstract: A process, and a corresponding device, for temporal image interpolation with corrected movement compensation, respectively use a consistency analysis step or circuit to analyse the defects in a field of movement which results from the movemenet estimation process step or device to perform either compensated-movement interpolation, or linear interpolation, depending whether the field of movement is estimated to be corrected or defective for the current point of the frame to be interpolated. Preferentially, to avoid abrupt transition between the two modes of interpolation, a process step or circuit enables intermediate values to be found which take into account the two modes of interpolation in the transition zones.

Nonlinear quincunx interpolation filtering

Abstract: Quincunx sub-sampling and interpolation techniques are widely used in many image and video signal bandwidth compression techniques like HDTV transmission systems. In this paper we consider the basic quincunx interpolation problem: interpolation of the missing samples of an orthogonally sampled image after quincunx sub-sampling with a factor of two. New median-based nonlinear interpolation techniques are developed and compared with traditional linear designs. It is shown that nonlinear interpolators result in considerably lower hardware complexity than good quality linear designs and in many respects even better image quality can be achieved.© (1990) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Apparatus to improve image enlargement or reduction by interpolation

Abstract: An image interpolation apparatus receives an image signal in the frequency domain. The image signal is supplied to a filter circuit. The output of the filter circuit is transformed by a two-dimensional fourier transformation circuit into a filtered image signal in the spatial domain. The filtered image signal is linearly interpolated by an interpolation circuit to enlarge or reduce the image representing the image signal. The filter circuit, the fourier transformation circuit and the interpolation circuit are under the control of a processor. The processor sets the filter circuit a filter function representing the inverse of the modulated transfer function of the interpolation circuit to compensate for the degradation caused by the modulated transfer function of the interpolation circuit.

Flexible approach to image warping

Abstract: This paper describes a novel approach to designing and applying spatial transformations to images, a technique that has only recently been exploited. The concept is to create and save the transformation as a look-up table (LUT) and then to use the look-up table to control the image resampling. This approach is very flexible; it is even amenable to transformations that cannot be implemented using classical approaches.© (1990) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

New shape-based interpolation technique for three-dimensional images

Abstract: The problem of interpolating a high-resolution binary-valued 3-D image given a lower-resolution grayscale 3-D image and a corresponding segmented 3-D image is addressed. Three algorithms for this problem are described. Algorithms 1 and 2 perform shape- and located-based binary interpolation. Algorithm 3, which subsumes algorithms 1 and 2, incorporates grayscale information as well as object shape and slice-to-slice object spatial relationships. Results show that algorithm 3 generates better interpolated objects than the segmented volumes arising from standard grayscale-based interpolation techniques. Algorithm 2, which subsumes algorithm 1, uses only the known presegmented volume to interpolate a new binary-valued volume. the methods show particular merit in cases where the objects to interpolate are thin tube-like structures, such as the coronary arteries. >

Learning receptor positions from imperfectly known motions

Abstract: An algorithm is described for learning image interpolation functions for sensor arrays whose sensor positions are somewhat disordered. The learning is based on failures of translation invariance, so it does not require knowledge of the images being presented to the visual system. Previously reported implementations of the method assumed the visual system to have precise knowledge of the translations. It is demonstrated that translation estimates computed from the imperfectly interpolated images can have enough accuracy to allow the learning process to converge to a correct interpolation.

Volume measuring instrument for object area to be detected

Abstract: PURPOSE:To measure the volume of the object and to accurately evaluate treatment effect by converting a slice image into a distance value image and performing image interpolation. CONSTITUTION:When multi-slice CT image information is inputted to this instrument, a contour extraction part 11 extracts the contour information of the object area of each piece of image information. Then a binary coding processing part 12 inputs slice image information containing the contour information, converts the slice image information into binary image so that the value of each picture element is '0' outside the contour and a constant value 100 inside the contour, and sends out the information to a distance value image information generation part 3. Then the generation part 3 adds +1 according to the values of picture elements along the contour every time the object part leaves the contour vertically or horizontally by one picture element in the object area and also adds -1 every time the object part leaves the contour vertically or horizontally by one picture element which is not in the object area, thereby obtaining distance value image information on each slice. Further, a linear interpolation part 4 performs the interpolation processing to obtain interpolated distance value image information and a volume arithmetic part 5 counts picture elements whose CT values are >=100 as to each piece of image information, thereby operating the volume of the object.

Interpolator for image display system

Abstract: PURPOSE: To realize a zoom function in which image interpolation circuits are continuous for an image display system in real time by adopting a bilinear interpolation algorithm realized in the form of a cascade one-dimensional interpolation circuit. CONSTITUTION: This system is provided with a means 16 storing an image to be interpolated. The system is provided with a means 14 for transferring this image to plural line buffers so that each line buffer may include the one pixel from the image for every first dimensional pixel location and each of continuous line buffers may include plural pixels over a second dimension. Further, the system is provided with a coefficient generation means 12 generating the interpolation efficient for an interpolation, a filter means 12 for generating an interpolated image value and frame buffer means 18 and 20 for storing the output of the filter means. Thus, the magnification due to the interpolation of the pixel in real time or a zoom function can be realized.

Comparison of interpolation methods in three-dimensional surface display

Abstract: The three-dimensional (3-D) object data obtained from a scanner usually have unequal sampling frequencies in the x y and z directions. Generally the 3-D data is first interpolated between slices to obtain isotropic resolution reconstructed then operated on by object extraction and display algorithms. Several interpolation methods are available. Here three interpolation algorithms: hnear polynomial and shape methods are used for comparison. The performances of these three algorithms are compared based on the image quality and accuracy in volume measurement of the 3-D object. 1.© (1990) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Efficient generation of 3-D images and off-axis projections using a PC-based parallel-processing subsystem

Abstract: A simple and inexpensive parallel-processing subsystem for the rapid generation and display of 3-D cardiac images from 2-D computed tomography and magnetic resonance imaging planes is presented. Parallel versions of algorithms for image interpolation, surface tracking, and 3-D image rendering were developed and implemented using a network of four INMOS transputers which are hosted by a PC-type computer. The subsystem accepts a stack of arbitrarily spaced 2-D image planes and efficiently produces a surface-shaded 3-D orthoprojection image which can then be arbitrarily rotated for viewing. It is concluded that this transputer-based subsystem hosted by a simple PC computer represents a cost-effective alternative to Pixar-style image processing workstations and is capable of generating high-resolution 3-D images in a reasonable amount of time. >

Image reproduction arrangement with reduced overheads - redefines image scaling functions when image window values are changed

Abstract: Images defined by pixel groups are reproduced on an image reproduction unit according to a general scaling function. When the user changes an image's window value the image is regenerated using a different scaling function defined by the current image window and level values. When at least one other image window value is changed, the image pixel group is replaced by corresp. values derived from the other scaling function and displays the image according to a scaling function defining a 1:1 identity function. ADVANTAGE - Some limitations and disadvantages of conventional systems, e.g. costly overheads, are eliminated.