Our Edi­tor does not like to be stretched, but finds a way that is bet­ter than most.

Sound+Image - - Contents - Jez Ford, Edi­tor www.face­book.com/SoundAndI­mageMagazine

Ire­cently cel­e­brated 10 years with Sound+Im­age magazine — I know, it seems for­ever, doesn’t it, but prior to that I was hack­ing my way through Malaysian tea plan­ta­tions, be­ing at­tacked by hor­nets and gen­er­ally hav­ing a good time, and prior to that, I was one of those UK hi-fi jour­nal­ists who have such a de­served rep­u­ta­tion for im­par­tial­ity. I hap­pened to look at my very first is­sue of

Sound+Im­age re­cently, and saw that my de­but edi­to­rial com­ment piece was on the sub­ject of as­pect ra­tio, and in par­tic­u­lar the hor­ror of vis­it­ing friends and find­ing them watch­ing short fat peo­ple on their screens, and ap­par­ently not even notic­ing. A decade on, I re­main highly sen­si­tive to as­pect ra­tio dis­tor­tions (even af­ter spend­ing longer in Aus­tralia and grow­ing to un­der­stand that in some places, RSLs for ex­am­ple, in­cor­rect as­pect ra­tio ap­pears to be man­dated as an ab­so­lute com­mand­ment, whether it’s the usual short fat peo­ple or some ex­tremely skinny ones dis­played on half a screen next to ex­cit­ing rolling Keno re­sults).

Thank­fully, the de­par­ture of 4:3 con­tent has largely fixed this per­sonal night­mare as far as tele­vi­sions go, so that the last hold-out for such con­straints is now the world of pro­jec­tion. I still some­times get to wit­ness a ded­i­cated home cinema in­stal­la­tion of ex­tra­or­di­nary qual­ity, only to find that 16:9 con­tent gets partly cropped and partly stretched in or­der to fill a 2.35:1 (or 2.39:1 or 2.4:1) ra­tio screen. If I ask why, the an­swer is usu­ally “be­cause no­body likes black bars down the side”. Short fat peo­ple are prefer­able, ap­par­ently, though most cer­tainly not to my eyes, even if I can see that sport, in par­tic­u­lar, be­comes a more im­mer­sive ex­pe­ri­ence when fill­ing the whole screen.

So I was most im­pressed re­cently to be shown a demon­stra­tion of a pro­ces­sor by Lu­ma­gen, which in­cor­po­rates an idea called non-lin­ear stretch. (It’s nei­ther new nor unique to Lu­ma­gen, but it’s new to me.) Non-lin­ear stretch keeps the cen­tre of the im­age at about the right as­pect ra­tio, then in­creases the stretch ra­tio fur­ther to­wards the edges. So at the sides, the stretch gets quite ex­treme. But of course our eyes reg­is­ter very lit­tle in the way of de­tail be­yond the point at which we fo­cus our at­ten­tion (try read­ing text in the next col­umn while keep­ing your eyes here). So for as long as the di­rec­tor keeps the ac­tion near the cen­tre of the frame, this non-lin­ear stretch is ex­tremely ef­fec­tive at achiev­ing the dual goals of fill­ing the screen, yet not mak­ing peo­ple too short and fat.

It wouldn’t work for all ma­te­rial — you wouldn’t want to watch an Academy-ra­tio Hitch­cock movie this way, since any­thing with a lot of pan­ning will suf­fer al­most a fish-eye ef­fect as ob­jects move from one side to the other. But for sport, it’s a def­i­nite suc­cess. (I should men­tion that Lu­ma­gen’s pro­ces­sors do an aw­ful lot else be­sides this par­tic­u­lar op­tion, in­clud­ing HDR map­ping and some ap­par­ently very im­pres­sive up­scal­ing to UHD. We’ll re­turn to them in fu­ture is­sues.)

This char­ac­ter­is­tic of vi­sion is also be­ing in­ves­ti­gated in vir­tual re­al­ity head­sets. The cur­rent crop of head­sets still have, IMHO, pretty piss-poor res­o­lu­tion which makes their use for en­ter­tain­ment rather like step­ping into a 480p YouTube video from 2005. But fix­ing that is not as easy as sim­ply putting in higher-res­o­lu­tion screens, be­cause the pro­cess­ing power re­quired to gen­er­ate and/or shift that high-res video ac­cord­ing to your head move­ments would be mon­u­men­tal. You’d prob­a­bly re­quire a head­set the size of a pump­kin.

But — given our in­abil­ity to per­ceive de­tail where we’re not look­ing, the high-res screens could show low-res im­agery ev­ery­where else, and just de­liver high res­o­lu­tion wher­ever our at­ten­tion is fo­cused. This idea is called foveated ren­der­ing, and clearly it will rely on eye track­ing that is ac­cu­rate and fast enough to get the job done pretty much as fast as your eye can dart around the im­age. Which is very fast — fast enough that no­body’s nailed it yet. But the goal of less pro­cess­ing, less power and smaller head­sets has put foveated ren­der­ing very much on the VR roadmap, and Google/Daydream posted in De­cem­ber about their ideas for how it might be ap­proached (see it via avhub.com.au/ fov — though be warned, it’s not light read­ing). Mean­while I was de­lighted to ex­pe­ri­ence a re­lated idea well ex­e­cuted by Lu­ma­gen’s pro­ces­sor. Any­thing to get rid of those short fat peo­ple. Cheers!

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