Showing papers on "Parametric Image published in 1999"

Parametric image stitching

Abstract: During electronic film development, convential film is scanned electronically to produce a series of views of the develing image. An early scan reveals the fast developing highlight detail, while a late scan reveals slow developing shadow detail. After development, the series of views is combined into a single image in a process called stitching. In the present invention, regression data is accumulated during development to describe a curve of density versus time of development for each pixel. After development, this regression data is used to recreate a regression curve of dentisity versus development time for each pixel. The time at which this curve crosses a density known to give optimum grain characteristics, called the optimum density curve, is used to create the brightness for that pixel in the finished stitched image. The invention further teaches weighting regression data as a function of time and density generally following proximity to optitum density curve.

Multi-frame alignment of planes

Abstract: Traditional plane alignment techniques are typically performed between pairs of frames. In this paper we present a method for extending existing two-frame planar-motion estimation techniques into a simultaneous multi-frame estimation, by exploiting multi-frame geometric constraints of planar surfaces. The paper has three main contributions: (i) we show that when the camera calibration does not change, the collection of all parametric image motions of a planar surface in the scene across multiple frames is embedded in a low dimensional linear subspace; (ii) we show that the relative image motion of multiple planar surfaces across multiple frames is embedded in a yet lower dimensional linear subspace, even with varying camera calibration; and (iii) we show how these multi-frame constraints can be incorporated into simultaneous multi-frame estimation of planar motion, without explicitly recovering any 3D information, or camera calibration. The resulting multi-frame estimation process is more constrained than the individual two-frame estimations, leading to more accurate alignment, even when applied to small image regions.

A New Approach to Double Tracer Studies

Abstract: Many scintigraphic studies are based on the comparison of two images recorded using different traces. The processing of these Double Tracer Studies (DTS) combines the difficulties of any image comparison and those arising from the fact that the images are obtained with different tracers. This is the reason why DTS are usually analysed visually. In this case, any number of views can be used and the acquisitions can take place at different times. However, when the construction of a parametric image, such as the difference or the ratio image is planned, contraints is the imposes, in most cases, the use of radionuclides with different energies. Even if these constraits are fulfilled, difficulties still remain, such as the differences in crosstalk (or background), in absorption and in the Point Source Responces of the detector (1). In this text we present a new method of DTS processing which is based on an original and rigorous approach to the problem.

Correction of errors in magnetic resonance images due to magnetic gradient non-uniformity

Abstract: A system and method for correcting systematic errors that occur in MR images due to magnetic gradient non-uniformity is disclosed for use with parametric analysis. A GradWarp geometric correction operation is applied in reconstructing quantitative parametric analysis images in regions of gradient non-uniformity. The method includes generating an error map of magnetic gradient strength as a function of distance for an MR image scan and acquiring MR data (60) that contain such systematic errors. The method next includes either calculating a measured diffusion image, a phase difference image (62,64,66), or similar image, based on the acquired MR data, and then calculating a corrected parametric image (68,70,72) using the error map and the measured diffusion image, the phase difference image, or other similar parametric image. The method is incorporated into a system having a computer programmed to perform the aforementioned steps and functions.