Julian Christou

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Although single cone receptors have been imaged <i>in vivo</i>, to our knowledge there has been no observation of rods in the living normal eye. Using an adaptive optics ophthalmoscope and post processing, evidence of a rod mosaic was observed at 5° and 10° eccentricities in the horizontal temporal retina. For four normal human subjects, small structures(More)
We quantitatively demonstrate the improvement to adaptively corrected retinal images by using deconvolution to remove the residual wave-front aberrations. Qualitatively, deconvolution improves the contrast of the adaptive optics images. In this work we demonstrate that quantitative information is also increased by investigation of the improvement to cone(More)
We demonstrate the recovery, without a priori object knowledge, of the unknown object and point spread functions PSFs from multiframe focal-plane data. By modeling the object Fourier spectrum as an unprejudiced linear combination of the cross-spectra of the measurements and the PSFs, we signiicantly reduce the number of degrees-of-freedom for the blind(More)
This paper introduces a blind method based on Bayesian maximum a posteriori estimation theory for restoring images corrupted by noise and blurred by one or more unknown point spread functions. Image and blur prior information is expressed in the form of parametric generalized Gauss Markov random field models. A method for estimating the GGMRF neighborhood(More)
In images of the human fundus, the fraction of the total returning light that comes from the choroidal layers behind the retina increases with wavelength [Appl. Opt. 28, 1061 (1989); Vision Res. 36, 2229 (1996)]. There is also evidence that light originating behind the receptors is not coupled into the receptor waveguides en route to the pupil [S. A. Burns(More)
We present an application of an iterative deconvolution algorithm to speckle interferometric data. This blind decon-volution algorithm permits the recovery of the target distribution when the point spread function is either unknown or poorly known. The algorithm is applied to specklegrams of the multiple star systems, and the results for UMa are compared to(More)
New near-infrared images of the young, nebulous intermediate-mass (Herbig Ae/Be) star LkH 198 using direct imaging, adaptive-optics compensated speckle imaging (AOCSI), and standard speckle imaging reveal complex structure in its circumstellar dust distribution. At high resolution, LkH 198 is found to possess a barlike feature which extends 3 00 from the(More)