I’ve been continuing my adventures in image manipulation with Matlab, taking the opportunity to play with a technique I’ve been interested in for a long time – ‘slit scan’ or ‘strip’ photography. A very brief (but rather maths-y) explanation of what’s going on in the clip above would be the following:
Let a video be defined by T frames each of dimension X-by-Y. Then the pixel value to be displayed at location x,y at time t is simply V(x,y,t) for some 3-dimensional array V; so the kth frame corresponds to the 2-d image Fk given by the plane T=k. But we may consider other planes to generate frames; by fixing a horizontal position X=k individual frames are images given by (t,y)=V(k,y,t) and iterating through these gives a new video V’(x,y,t)=V(t,y,x).
If that tells you everything you need to know, you can look at a couple more examples here and (more abstractly) here. Otherwise, read on for a fuller explanation!
Having finally dragged myself into the smartphone age I was at last able to get set up with the mobile version of TriggerTrap, a timelapse gizmo created by some friends of mine. I already had a starting project in mind, to capture the antics of my Roomba.
Having recently returned to Edinburgh for an MSc, I find myself studying Matlab for the first time in a decade. I always feel that the best way to familiarise yourself with a programming language is to have a goal in mind, and I remembered from a JMM talk that Matlab can be used for image processing. So whilst I’d normally reach for python to tackle an unfamiliar task, on this occasion I took the rather circuitous route of Matlab, processing and some video-editing tools.
With my current camera gear filling an entire carry-on bag, a laptop is too much extra bulk/weight, so on my last few trips I’ve been surviving on an ipod touch for limited web browsing, email access and so on. This got me wondering whether a tablet would be a good fit, especially if it gave me the ability to review, back-up and share photos on the move whilst also improving my internet experience and offering video/ebooks for when IFE doesn’t cut it. The launch of the latest ipad, with a screen resolution that puts even my desktop to shame, provided just the extra nudge I needed to explore the idea seriously.
But in researching my options I found myself immediately confronted by a stack of conflicting information regarding what was or wasn’t possible with the ipad. Presumably to encourage uptake of the higher-capacity models, apple don’t include a memory card slot, nor standard USB sockets, on the ipad. Instead there’s an external connection kit, and establishing which permutations of ipad model / iOS version / camera brand / connection type would co-operate was not easy – perhaps not helped by the lack of tech savvy from some users, as many comments on apple’s site strongly suggested PEBCAK. A visit to the store didn’t allow for a practical test as they didn’t have adaptors in stock, but they were willing to accept a return of the ipad if it proved not to be suitable for purpose. Probably knowing that I’d really struggle to give it back after playing for a while, even if some sort of android tablet would be more useful for my needs!
Well, mine arrived yesterday, and I’m pleased to report that for the Canon 550d (T2i) – and presumably their other sd card based models – it all plays together beautifully. But in trying it out, I stumbled into various other seas of online confusion regarding photo handling, so I thought I’d collect together what I’ve learnt so far (admittedly, in all of 24 hours) in the hopes it helps save others some time/effort. This is not a guide to taking photos with the ipad, which still strikes me as a ridiculous idea!
The third Bath Upchuck juggling convention was (due to the magic of February’s 28 days) exactly a month ago today, and I’m still wading through the footage… This year I was a bit more organised on the day, and claimed one of the squash courts as a slow motion film studio for a couple of hours. You can view the highlights above – as well as some stills from wandering with the dSLR – but I promised to compile reels for each individual performer, and those are taking time. Still, I managed to post a video each evening of last week, and should be able to do the same for the next, so keep checking the dedicated playlist. In a departure from my usual methods, I also shot some timelapse:
(Cross-posted to Modulo Errors)
Just a quick note to mention two talks from the Edinburgh International Science Festival, which my flatmate chaired and I took some photos at: Marcus du Sautoy’s The Num8er My5teries and Ian Stewart’s Cows in the Maze. Summaries, courtesy of Haggis the Sheep, can be found here and here respectively.