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!
Continue reading Space-time manipulation (with buses)
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.
Continue reading RoombaTrap
I got this year’s travel off to a strong start, spending a fortnight flitting about California. The official reason was academic, as I attended and presented at the Joint Mathematics Meetings in San Diego; I pulled out some mathematical highlights from that over on Modulo Errors. But I also took the opportunity to engage in a `status run’ with British Airways and Hilton Hotels, securing silver and gold tiers in their respective loyalty programmes. As such I racked up close to twelve thousand miles in the air, and stayed at six different hotels, variously visiting London, San Diego, San Francisco, Los Angeles and Coronado. For those interested in the minutiae of such a project, I produced a lengthy report for the FlyerTalk forums. And of course, I took a fair few photos along the way, which have been sifted down into a collection of flickr galleries.
About a month ago I read this excellent article on the fall from grace of the name ‘Hilary’. That alerted me to the fact that you can easily get US Social Security records on frequency of first names right back to the 1880s. Although Hilary focused on the raw numbers, I commented that I’d be interested in seeing the behaviour with respect to gender – specifically the tendency for ‘male’ names to become unisex or even predominantly ‘female’. Today I actually got around to crunching the data!
I found myself with 37,407 names that had been used for males, and 62,318 for females – so we immediately see that there’s a lot more diversity for female names. Of all these, 9800 are common to both genders – but only 8,564 have instances with both genders in the same year. Any such year I could use for a scatter plot of the proportion of males with a given name, out of all people with that name. So a value of 1 indicates a name was assigned only to males that year, with 0 showing that only females received it. Here’s the ratios for `Hilary’:
Proportion of male Hilarys.
Continue reading Gender shifts in US given names
This year has probably been my most travel-full so far, racking up over 21,000 miles across 15 flights – with two more still to go, and another half dozen scheduled for January. Although I despair of organising my photos from domestic wanderings, I do now have most of the international trips added to my flickr travel collection. For convenience, the new additions are:
In the process, I’ve become somewhat hooked on the art of maximising returns from airline and hotel loyalty programs, a task made much easier with the guidance of the wonderful folks of FlyerTalk. With the demise of SoSauce, I’ve been in search of a way to keep travel journals, and so I wrote up both Assisi and Gibraltar for their trip report forum. Be warned, though, that given the audience, the emphasis is more on the technicalities and perks of the journey, than the merits of the destination! I still toy with setting up a straylight subsection for such musings, but would I ever find the time to update it properly?