Abstract:
A method for determining a number of balls in a projection space comprises determining a projection of a portion of a ball grid array, determining at least one local maximum of the projection space for a given threshold, and determining at least a distance between adjacent maximum. The method further comprises determining an inter-peak histogram of the distances, determining an inter-ball distance for each pair of adjacent balls that has the maximum value of the inter-peak distance histogram corresponding to the pair of adjacent balls, and determining a position of a first ball and a position of a last ball. The method comprises verifying the position of the first ball and the position of the last ball based on a general inter-ball distance, and determining the number of balls.
Abstract:
A system and method for electronic archival of paper-based technical drawings includes a system having a processor, a form learning unit in signal communication with the processor for learning the form of a model drawing image, a form localization unit in signal communication with the processor for localizing the form of an input drawing image, an optical character recognition unit in signal communication with the processor for optically recognizing identification text of the input drawing image, and a result verification unit in signal communication with the processor for verifying the results of the recognized identification text of the input drawing image; and further includes a method for providing a model drawing image, learning the form of the provided model drawing image, receiving an input drawing image, localizing the form of the input drawing image, optically recognizing identification text of the input drawing image, verifying the results of the recognized identification text of the input drawing image, and storing the input drawing image and the corresponding verified identification text into a drawing database.
Abstract:
A method for matching images includes the step of providing a template image and an input image. A Laplacian-of-Gaussian filtered log (LOG-log) image function is computed with respect to the template image and the input image to obtain a Laplacian-of-Gaussian filtered template image and a Laplacian-of-Gaussian filtered input image, respectively. An energy function is minimized to determine estimated geometric transformation parameters and estimated photometric parameters for the input image with respect to the template image. The energy function is formed by weighting non-linear least squared differences of data constraints corresponding to locations of both the Laplacian-of-Gaussian filtered template image and the Laplacian-of-Gaussian filtered input image. The estimated geometric transformation parameters and the estimated photometric parameters are output for further processing. The method allows for image matching under non-uniform illumination variations.
Abstract:
A fast localization with advanced search hierarchy system for fast and accurate object localization in a large search space is based on an assumption that surrounding regions of a pattern within a search range are always fixed. The FLASH system comprises a hierarchical nearest-neighbor search system and an optical-flow based energy minimization system. The hierarchical nearest-neighbor search system produces rough estimates of the transformation parameters for the optical-flow based energy minimization system which provides very accurate estimation results and associated confidence measures.
Abstract:
An illumination compensation system for correcting smooth intensity variations due to illumination changes is based on an assumption that an underlining image reflectance function is approximately a piecewise constant and that an image irradiance function is spatially smooth. The system first takes the logarithm of an image brightness function. Gradient constraints are then computed using a finite difference. Reliable gradient constraints are selected based on a local uniformity test. A process is subsequently applied to estimate the logarithmic irradiance function. A logarithmic irradiance function is subtracted from the logarithmic image brightness function and an exponential operation of the above subtracted image function is taken and an illumination compensated image is outputted from the system.
Abstract:
An intensity inhomogeneity correction system includes a log operator which performs a log operation on the intensity values of the original MR image. A regular grid generator partitions the image domain and then a compute and select establishes reliable orientation constraints at grid locations. A bias field surface reconstructor reconstructs a bias field surface from selected orientation constraints with a thin-plate spline by using a preconditioned conjugate gradient. An intensity inhomogeneities remover subtracts an estimated bias function from the original log image and an exponential operation on the bias-field corrected log image provides a corrected image.
Abstract:
An adaptive hierarchical neural network based system with online adaptation capabilities has been developed to automatically adjust the display window width and center for MR images. Our windowing system possesses the online training capabilities that make the adaptation of the optimal display parameters to personal preference as well as different viewing conditions possible. The online adaptation capabilities are primarily due to the use of the hierarchical neural networks and the development of a new width/center mapping system. The large training image set is hierarchically organized for efficient user interaction and effective re-mapping of the width/center settings in the training data set. The width/center values are modified in the training data through a width/center mapping function, which is estimated from the new width/center values of some representative images adjusted by the user. The width/center mapping process consists of a global spline mapping for the entire training images as well as a first-order polynomial sequence mapping for the image sequences selected in the user's new adjustment procedure.
Abstract:
A multi-scale approach to enhancement is taken where enhancement masks are generated at different scales and then combined together using a pyramid scheme. Each mask is computed from applying directional sensitive Laplacian kernels, which is responsible for extracting images of low contrast, followed by an adaptive non-linear mapping. This non-linearity is crucial in virtually eliminating edge overshoots. Furthermore, the input image may also be preprocessed by an edge-preserving smoothing filter to reduce the noise effect.