Retinal Fundus Detection Using Skew Symmetric Matrix

Author(s):  
Kiranjit Kaur ◽  
. Priyadarshni

The retina is the light sensitive tissue, lining the back of our eye. Light rays are focused onto the retina through our cornea, pupil and lens. The retina converts the light rays into impulses that travel through optic nerve to our brain, where they are interpreted as the images. The task of manually segmenting fundus from retina images is generally time-consuming and difficult. In most settings, the task is done by marking the fundus regions slice-by-slice, which limits the human rater’s view and generates distorted images. Manual segmentation is also typically done largely based on a single image with intensity enhancement provided by an injected contrast agent. In the current research the fundus is detected and extracted in retinal image. Fundus is distinguished from normal tissues by their image intensity, threshold-based or region growing techniques. The fundus in this approach is detected with the help of geometric features. Skew symmetric matrix is used to avoid any angular orientation. In this approach the accuracy on fundus is quite promising.  Accuracy of fundus detection is improved according to the area and the acceptance rate .In this approach ,once the image is loaded, it is filtered and normalized. Then superpixels are generated using linear iterative clustering approach and the features are generated. From the available set of features, some of the features are selected using sequential forward selection approach .Classifier is constructed in order to determine different classes in a test image. Proposed work is two class problem in which algorithm is applied that consists of skew symmetric matrix .Experimental results show substantial improvements in the accuracy and the performance of fundus detection as well as in false acceptance rate and false rejection rate.

10.37236/1263 ◽  
1995 ◽  
Vol 3 (2) ◽  
Author(s):  
Donald E. Knuth

A combinatorial construction proves an identity for the product of the Pfaffian of a skew-symmetric matrix by the Pfaffian of one of its submatrices. Several applications of this identity are followed by a brief history of Pfaffians.


2007 ◽  
Vol 42 (8) ◽  
pp. 729-736 ◽  
Author(s):  
James W. Cooper ◽  
William E. Wade ◽  
Christopher L. Cook ◽  
Allison H. Burfield

Purpose To document and compare the outcomes from monthly drug regimen review recommendation acceptance and rejection in one skilled nursing facility by one consultant pharmacist (CP) in the fourth year of evaluation with the prior 3 years' data. Method A non-randomized, observational, prospective cohort study with all patients being residents for at least 30 days over the 12-month period (October 1, 1997 to September 30, 1998) in a skilled nursing facility with more than 100 beds. The admission problem-oriented records of all patients and their respective CP reports were screened for pharmacotherapy recommendations and subsequent acceptance and rejection on a monthly, repeated-measures basis for 12 months. There were 2,004 monthly drug regimen review (DRR) reports. The percentage of DRR reports that made recommendations was tabulated. Written recommendations made to attending physicians that were either accepted or rejected within 3 months were analyzed. The charges for adverse outcomes were calculated from billing records or prior studies of the outcome. These results were compared with prior 1- and 2-year studies of outcomes within the same setting. Carryover effects of recommendations implemented in prior periods were also calculated. Results There were 178 recommendations made in 2,004 DRR reports (8.9%). A low acceptance rate, 27 of 178 recommendations (15.2%), resulted and was combined with carryover of prior acceptance in a cost savings of $113,962. The 151 recommendations that were rejected resulted in $226,503 of presumed unnecessary costs to the health care system. A prior 2-year study of recommendations with an acceptance rate of 89% showed costs savings of $111,609 per year with acceptance and $112,297 added costs per year with 11% rejection. The first-year study had a 93% acceptance rate at a projected cost savings of $43,854 and costs increased by $60,825 with a 7% rejection. The costs of recommendation rejection in the fourth year were substantially higher, with a higher rejection rate than was seen in the prior 3 years of observation. Conclusion Documentation of the costs from CP intervention should factor in costs of rejection that may increase with the percentage rejection of recommendations, length of observation period, and may vary between facilities.


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