The point-spread function (PSF) of a camera can seriously affect the accuracy of radiometric calibration and measurement. We found that the PSF can produce a 3.7% difference between the apparent measured radiance of two plaques of different sizes with the same illumination. This difference can be removed by deconvolution with the measured PSF. To determine the PSF, many images of a collimated b...

We present results of concurrent maximum likelihood restoration implementations with spatially-variant point spread function (SV-PSF) on both synthetic and real datasets from the Hubble Space Telescope (HST). We demonstrate that SV-PSF restoration exhibits superior performance compared to restoration with a spatially invariant PSF. We realize concurrency on a network of Unix workstations, and a...

Three-dimensional microscopy by computational deconvolution methods requires accurate knowledge of the point spread function (PSF) that characterizes the microscope. Experimental PSF’s can only be measured over small regions about focus because the small objects necessary for PSF measurement are dim. Theoretical computation of the PSF requires accurate knowledge of all the experimental setup pa...

Improved preservation techniques have the potential to improve transplant outcomes by better maintaining donor organ quality and by making more organs available for allotransplantation. Persufflation, (PSF, gaseous oxygen perfusion) is potentially one such technique that has been studied for over a century in a variety of tissues, but has yet to gain wide acceptance for a number of reasons. A p...

Recovering an un-blurred image from a single motion-blurred picture has long been a fundamental research problem. If one assumes that the blur kernel – or point spread function (PSF) – is shift invariant, the problem reduces to that of image deconvolution. Image deconvolution can be further categorized as non-blind and blind. In non-blind deconvolution, the motion blur kernel is assumed to be k...

In recent years single particle tracking has significantly contributed to the study of intracellular molecular dynamics [2]. Particle tracking primarily consists of localizing particles in three dimensions (3-D) from a number of images acquired by fluorescence microscopy. While many approaches have been proposed for the lateral (i.e., x-y) localization of particles from acquisitions that are (a...

Context. We address the issue of controling the systematic errors in shape measurements for weak gravitational lensing. Aims. We make a step to quantify the impact of systematic errors in modeling the point spread function (PSF) of observations, on the determination of cosmological parameters from cosmic shear. Methods. We explore the impact of PSF fitting errors on cosmic shear measurements us...

This ISR briefly reviews how the WFC3 UVIS channel focus and alignment impact the PSF. The aim is to verify whether we can identify any simple PSF measurement that would allows to monitor these quantities. We find that the centering of the PSF within a pixel is a crucial parameter that needs to be calibrated or corrected for and that PSF sharpness is the most promising parameter.

The robust estimation of the tiny distortions (shears) of galaxy shapes caused by weak gravitational lensing in the presence of much larger shape distortions due to the point-spread function (PSF) has been widely investigated. One major problem is that most galaxy shape measurement methods are subject to bias due to pixel noise in the images (“noise bias”). Noise bias is usually characterized u...

Prostacyclin-stimulating factor (PSF) acts on vascular endothelial cells to stimulate the synthesis of the vasodilatory molecule prostacyclin (PGI2). We have examined the expression, regulation, and hemodynamic bioactivity of PSF both in whole retina and in cultured cells derived from this tissue. PSF was expressed in all retinal cell types examined in vitro, but immunohistochemical analysis re...