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<p class="MsoNormal"><span style="font-size:11.0pt;color:black">John “Jack” Yellott passed away last week following a decline in health from various medical problems. Jack spent most of his career at the University of California at Irvine, joining the faculty
in 1971, and becoming emeritus in 2002. He received his Ph.D. in mathematical psychology from Stanford in 1966, followed by 5 years on the faculty at the University of Minnesota and a year at Princeton’s Institute for Advanced Study before moving to UCI.
Jack remained active during “retirement,” launching a new project on improving the legibility of text corrupted by ocular blur with image processing. A more detailed obituary may be forthcoming from his university. Those of you that knew Jack may like to
take this opportunity to share a few memories; I’ve added a few of my own at the end of this message.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:black"><img width="640" height="640" style="width:6.6666in;height:6.6666in" id="Picture_x0020_2" src="cid:image001.png@01D5B045.4268E3E0" alt="A picture containing wall, indoor, person, man
Description automatically generated"></span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:black"> (thanks to Kimberly Jameson for providing this picture of Jack in the lab)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:black">Jack’s own description of his work from his UCI web site states:</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:black"> </span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><i><span style="font-family:"Arial",sans-serif;color:#333333;background:white">I've worked on a variety of topics, including retinal anatomy, texture perception, image processing, learning, reaction time, and choice
and ranking. Currently I am studying the possibility of creating visual stimuli that are precorrected for the optical phase distortions (phase reversals, or "spurious resolution") that occur when a human eye is out of focus--e.g., when a person who needs reading
glasses tries to read without them. Computer modeling shows that correcting spurious resolution can greatly improve the legibility of defocused text. In principle such an improvement can be achieved in advance, by reshaping printed letters in such a way that
subsequent defocus in the eye restores them to their proper shapes. I am working on the mathematical theory that explains this improvement and establishes its quantitative parameters. The theory that has emerged provides a complete account of this type of
phase-only deconvolution, and explains its characteristic properties and practical limitations.</span></i><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:black"> </span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:black">I first met Jack early in my career as a graduate student at UC San Diego, when Jack came to visit with his optical-fourier-transform-in-a-suitcase apparatus that he used to display the power spectra
of retinal photoreceptor arrays, coining the term “desert island spectrum” to describe a central “island” surrounded by an “atoll” corresponding to the frequencies produced by the nearest-neighbors. Jack introduced me to my future NASA colleagues at my first
ARVO meeting in 1982, and so I gratefully give him a large share of the credit for me ending up here in 1986. Jack has been a great colleague and friend for my whole career, and I have been a been a regular recipient of the hospitality Jack and and his wife
Dorothea’s hospitality at their Laguna Beach home.</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:black"> </span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:black">Sometime in the 90’s I was strolling with Jack through the Rochester convention center at an OSA meeting, and he said, “this is wonderful, there are all these vision people here.” I thought this
was kind of odd, wasn’t he a vision person too? No, he said, he was a mathematical psychologist, because that had been the area of his PhD. Nevertheless, thanks to his many contributions to the field, I think that the vision community counts him as one of
our own, and he will be missed.</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:black"> </span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
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