Getting the supermoon out of proportion

I’ve enjoyed looking at the many news-website photo galleries of last week’s ‘supermoon’. Many of the shots purport to show how unusually large the moon looked last Saturday night, and some are quite remarkable. Here’s a photo shown prominently on Gizmodo, under the headline ‘The Supermoon really was super huge!’:

Gizmodo supermoon

That does indeed look impressive, but the commenters quickly realised there was a problem, because they knew the size difference was overhyped. The ‘supermoon’ was a rare-ish conjunction of a full moon and the moon’s closest approach to the earth. The latter happens every three years, and the conjunction about every 20. The moon was 2% closer, its gravity 3% stronger, and the spring tides here on earth were 5% higher than usual as a result. NASA reckon the moon appears 14% bigger at its closest position than at its furthest, but most of the time the moon is somewhere inbetween, and the differences aren’t noticeable. Yet the above shot definitely shows a huge moon hovering by the Lincoln Memorial, so what’s happening?

There are a couple of things going on here. First of all, when you’re physically outside and looking into the sky, the apparent size of the moon is way more affected by its position than its distance. For reasons not entirely understood, the moon appears far larger when nearer the horizon. This is the moon illusion, and is illusory because there’s no actual difference – if you hold up a ruler, or take a series of photos, it’s obvious the size never changes (in fact the moon is 1.5% smaller nearer the horizon, but that’s too small to notice anyway). Many Gizmodo commenters concluded that the photos were showing this illusion. But this can’t be correct, as the moon illusion doesn’t work in photos1. At one point someone suggests that the moon will always look big if you point a telephoto lens at it, and they were immediately shot down – after all, there’s the Lincoln memorial for comparison, isn’t there? But I’m pretty sure this person was correct and the naysayers were wrong.

It is a telephoto lens. It took me a little while to get the optics straight in my head, but the size of the building makes no difference. If the moon’s as tall as the building, it just means the photo was taken from further back. Writing this out now, it all seems obvious and I’m worried the following will seem patronising. But both I and some commenters were clearly confused for a while, so I figure it’s worth explaining.

Imagine you’re standing on a flat plain. The moon is always the same size in the sky, no matter where it is (ignoring the effects of the moon illusion). Now imagine there’s a single, distant tree on the horizon. If the moon sets behind it, the moon is going to appear substantially bigger than the tree, simply because the tree is far away. If you were to use a telephoto lens to zoom in until the moon filled your photo, the moon and the tree would both get proportionally bigger as you zoomed, and the moon would look much larger than the tree. But as you walk closer to the tree, the size of the moon will stay the same while the tree gets bigger. Eventually you’ll obviously be standing next to a tree which seems far, far bigger than the moon.

So it’s the same with the Lincoln Memorial photo. It’s been taken from far enough away that the memorial appears small in relation to the moon, but zoomed in enough that you can only see the two objects. If you’d taken a photo with a regular lens, you’d see far more of the city and the moon would look its normal size. If you’d walked closer, the Memorial would have quickly dwarfed the moon.

Most supermoon galleries are full of photos using this same trick. Probably because the newsdesk photo editors had to show something. Which I don’t mind at all – anything that makes people look at the moon more closely is fine with me.

  1. Phil Plait suggests the Ponzo illusion might contribute, but I’m skeptical in general, and I don’t think there’s enough depth in these photos for it to kick in anyway []

Uganda Humanist Schools exhibition launch

Big day today – my Uganda schools exhibition opens at Conway Hall this evening. This post should go up just as it starts. I’m currently pretty nervous and excited – nobody’s really seen the room before today, so I’m really hoping it goes down well. Hopefully there’ll be 30 or so people coming, and I’m breaking out the jelly babies. Here’s one of the walls:

UHST Exhibition

More shots of the room are on the official exhibition site. My last exhibition was frustratingly difficult to put online due to release form issues, and I’m really happy there’s a proper permanent presence for this one. New Humanist tweeted about it this afternoon, which was lovely of them.

I’ve been planning this for almost a year. It’s the culmination of my final university project – I just need to hand in some example images and shots of the exhibition room in May, and that’s my degree done. But the main aim was to help raise money and awareness for the Uganda Humanist Schools Trust, which supports the three schools. Here’s how it’s described at the exhibition:

The Uganda Humanist Schools Trust supports three Ugandan schools, each of which offers liberal, humanist education to needy children. The schools are in impoverished rural areas, where few families can pay for education, and where many children, orphaned by disease, are cared for by extended family members. This exhibition aims to show a snapshot of the day-to-day life of the children at the schools.

The three schools are first and foremost a humanitarian response to the desperate need to provide educational opportunities for such children. However, they are also part of a pioneering experiment to create schools in Africa with a liberal, humanist ethos. As one school principal explains:

Every person in this school is treated as a human being. If one person is hungry it is a problem for us all. We take care of each other. We apply reason and science to solve our problems and do not rely on superstition and prejudice.

The schools were started on a shoestring by Ugandan humanists. Facilities are poor but improving, thanks to support from members of humanist organisations like: The Rationalist AssociationNew Humanist, the International Humanist and Ethical Union, the British Humanist Association, and the work of the UHST. The schools desperately need support. You can find out more information, including how you can help, via the website, at www.ugandahumanistschoolstrust.org.

I just yesterday read the March 2011 report on the Mustard Seed School, which has very recently been able to sink a borehole and water pump, so they finally have clean on-site water. Before, they had to queue for hours at the local pump in the grounds of a local church. This will make a huge difference, and they’ll also use the pump to provide water for the local community. Fantastic.

I’ve really had a brilliant time from the moment I set foot in Uganda to today’s launch, and I’m very grateful to the UHST for trusting me enough to essentially give me free reign to take / use photos. Can’t believe my luck, to be honest.

How does low-resolution colour affect a photograph?

For my dissertation I’ve been researching how the physical structure of our visual system affects the way we perceive paintings and photographs. I’m been particularly interested in how the cells in the retina make a difference, given that they’re obviously fundamental in how we see. There’s been a fair bit of research done in this area, and a few investigations relate to photography, which is obviously of interest to me. One in particular is causing me some trouble, as I think it’s quite dramatic, but sometimes I wonder whether there’s actually anything that needs an explanation. It relates to our perception of colour.

It’s pretty well established that we have have two visual pathways, fed by different cells on the retina. One works in black and white and works very quickly – this system is older, evolutionarily-speaking, and is shared by mammals. The other works in colour, but is much slower – this system we only share with primates. When you look at the actual cells, you find that those for colour are larger than those for black/white. This means we can’t see as well in colour as we can in black/white – there are fewer cells per area, so we can’t see as much detail.

Obviously, this isn’t something we notice in day to day life, so it seems reasonable to suggest the brain is making up for this difference. We know the brain has a colossal role in how we see the world – for starters, the image on the retina is upside-down, and our brains flip it. When you look at the raw data arriving from the retina, it’s amazing we can see anything at all. So the brain is certainly up to the task. But is this difference in colour resolution something we can detect?

A hypothesis put forward in Margaret Livingstone‘s fascinating book Vision and Art: The Biology of Seeing, says we can see the results in some paintings. Here’s one by Raoul Dufy:

Raoul Dufy Flowers

We have no trouble recognising this as a bowl of flowers. Yet when you look, the colours aren’t within the lines. At times they’re way out. But we don’t get confused by this – indeed, we don’t even register it at first. Prof. Livingstone’s hypothesis is that the resolution of colour is so rough that Dufy doesn’t need to colour within the lines – the brain is continually fitting rough colours to the shapes it finds in the much higher resolution black/white system. Here’s another example by the same guy:

Raoul Dufy Orchestra

The violin players in the lower-left look fine at first glance. It’s only when you look more closely that you realise the red of the violins has no real shape. It’s just a blotch. But our brains fit it roughly to the shape of the violin, and we understand it fine.

The theory relies upon the brain having access to high resolution black/white data, which it fits the colour into. Here’s a greyscale version of the orchestra:

Raoul Dufy Orchestra B/W

While Raoul Dufy plays fast and loose with the colour, when it comes to black and white everything is much more normal. The shapes are clearly defined – there are obvious lines to everything.

Ok, so far, I reckon this is an interesting theory. My immediate thought is to wonder how much difference cell size can actually make – large colour cells are still, presumably, pretty small. But I’m no expert, and have to defer on this. Let’s assume the physiology of the theory makes sense.

I figured, if high-quality black/white data is important, this effect must be particularly strong with photography. After all, the detail on a photo is far in excess of anything in a painting. So I started playing around. Here’s a photo I found on Flickr that seemed apt. It’s by jonnyr1, and is creative commons licensed:

Violin Dude - Original

Let’s separate this into black/white and colour:

Violin Dude - Original B/W

Both versions have very fine details. The shape of the violin, his hand, and the windowframes behind him are all clearly defined. I’m going to blur the colour information, then recombine it with the black/white. Here’s the blurred colour:

Violin Dude Edit 1 - Blurred Colours

That’s obviously far less clear. You’d have trouble recognising the shape as a violin, I’d say. Add this to the black/white image and you get:

Violin Dude Edit 1

What do you think? I’d say on first glance you might not even notice anything was up. The violin is the colour of a violin, and nothing about it looks odd. The red/yellow/green stripe on the behatted gentleman’s jacket is still clear. Direct comparison with the first image shows differences, and once you start looking they become more obvious. But for such a huge loss of colour information, it’s still remarkably intact.

Blurring the colour info isn’t quite the same as smearing it outside the lines – the colour fades as it’s blurred. So I think it’s fair to boost the saturation a touch to make up for this:

Violin Dude Edit 1 - With Saturation

I’d say this makes it even closer to the original. (in all of the remaining steps I’ve given the same saturation boost).

So how far can we push the blurring?

Violin Dude Edit 2 - Colour Channels

Now you’re starting to lose the shape of the background windowframes. Everything’s becoming a bit nothingy. The combined image looks like this:

Violin Dude Edit 2 - with saturation

Still not bad. The window frames are most definitely blue – it takes a careful look to see the blue is spreading into the windows themselves. The yellow window is still yellow. The violin is still entirely intact, although the guy’s hands are going a bit odd. Mr Hat’s jacket is still obviously striped. How much further can we push it? For the next step I’ve applied a lot more blurring:

Violin Dude Version 3 - Colour channels

Nothing is recognisable now. It’s all just vague blobs. Combined, this looks like:

Violin Dude Edit 3 - Combined with saturation

Obviously we’re starting to lose a lot of detail now. But the violin is still clear, as are the windowframes and yellow window. The jacket stripes are almost gone, but retain a hint of colour. The guy on the right has barely changed since the initial photo. Yet in the colour data they’re hardly there are all.

What do you think? My worry is: is this impressive? Is this a phenomenon that’s calling out for an explanation?

I’m concerned I’m convincing myself it is, and I need some fresh eyes. It has the feeling of something a philosopher could come along and destroy. The theory of the brain making up for low colour resolution does make intuitive sense, but is it really possible that, if this weren’t the case, we’d be confused whenever colours drifted from their boundaries? I’m not sure how to judge that.

100 favourites

For the first time, one of my photos has reached 100 favourites on Flickr:

Flood dancing couple - 7

By most metrics, this is by far the most popular photo I’ve ever taken. It regularly gets posted to blogs / adapted in mashups, and was also used on the cover of an Australian folk album.

I took it on the day Stratford flooded, but I really really wanted to stay in and read the newly-released Harry Potter 7, and I honestly remember thinking “what are the odds I’ll take something any good anyway?”. Went out anyway, and saw this couple salsa-ing in the floodwaters. I took a bunch of shots, but this is the one people seem to like most. I gave the couple my card, and they’ve had equal share of anything I’ve received.

It’ll be a while before this happens again – the second-place photo has 8.

What happened when we gave cameras to the Ugandan kids

Isaac Newton Pupil Shots #030Just before heading out to Uganda I picked up a bulk load of digital cameras on eBay, with the aim of handing them out to the pupils and seeing what kind of pictures came back. I was originally going to use disposable film cameras, but these 20 little Vivitar 3-megapixel compacts came to £3 each – and I could re-use them – so I bit the seller’s hand off. When he heard my plans he sent along a few extra for free, which was very nice of him, and the night before leaving I spent an hour shoving titchy cameras into every available cranny in my luggage – then spent a week hearing little beeps while sifting through clothes, and having to find the relevant camera before its battery died. It was worth it.

The cameras weren’t great. The lenses were plastic, the screens on the back were barely visible, the sensors were incapable of taking sharp shots indoors1, and battery life was about 90 minutes. But they at least tried to expose correctly (unlike disposable film cameras, which just fire the flash and hope for the best) and could store 30 pictures. They’d do.

Once over there it was clear I’d only have time for this at the school we stayed at for a week, the Isaac Newton School. So I roped in Sam and Katie, the two Swansea students saying with me, and we figured out a plan. I’d been hoping we could teach a class, spending 20 minutes on the optics of lenses before introducing the cameras and sending the kids out to take photos. But this wasn’t possible as the teachers get paid per lesson and we didn’t want to deprive anybody, so we figured we’d hand out the cameras during a ‘break’ (timetables were pretty fluid), and collect them back a bit later.

And that’s basically what we did, except I made a mistake when talking to the Headmaster. I told him the plan, and explained that the school could keep the cameras at the end. Which I thought would make him happy. And it did. Except, once we handed out the cameras he and the staff promptly went around collecting them back in, because they were school property and the kids might lose them.

Hmph. But the kids had still had the cameras for 20ish minutes, so we borrowed them from the Head and took them back to the hotel to see what we’d got:

Isaac Newton pupil photos - 1

Isaac Newton pupil photos - 2

I like them! It’s cool to see the expressions they pull when posing for their friends – they’re quite different from the portraits I took. I also particularly liked this:

IsaacNewtonVivitar #060

I didn’t see any games the whole time I was there – there’s no way we’d have known about this otherwise. And then Sam spotted a sadly-anonymous work of utter genius:

Isaac Newton Pupil Shots #014

The cameras also had a (very) rudimentary video mode which some of the kids activated accidentally, so the full set has a few little clips. I kept a fair few of these back, though, as it felt a little off to upload little moments people didn’t know would be shared – but some are ok.

I’d certainly do things differently next time2, and it’s a shame there aren’t more, but I’m pleased with how it turned out nonetheless. Thanks to Sam and Katie for helping! The set is here.

  1. or outdoors sometimes. Not that I managed to blur any 7D pictures taken in African sunlight. Oh no. []
  2. if you ask me in person I might possibly have a few more details I can’t really say in public []

Uganda photos: finished

Isaac Newton School #260I finally finished processing the Uganda photos/videos this afternoon. Hooray! It is quite the relief, not least because now they’re in the cloud I can stop worrying about hard drive failures taking out my summer’s work.

Much as I love Flickr, I have to admit it’s easier to browse the shots on Facebook. FB’s new album layout makes everything look pretty, and the refresh-less Next/Previous is very pleasant. Flickr has the edge in pretty much everything – quality, information, accessibility – but FB is hard to beat for quick browsing. The albums (of selected shots) are here if you’ve a login. If not: Mustard Seed School, Humanist Academy, Isaac Newton School, Elsewheres.

Everything’s neater on Flickr, though, and there are far more images: the collected albums are here, with just the highlights here.

I’m pleased with how the photos turned out, and hopefully the Uganda Humanist Schools Trust will find them useful. After six weeks of editing it’s easy to notice the mistakes, and the shots I didn’t take, but that’s just all the more incentive for next time. I was hoping to go back to Uganda before the end of the year, but I don’t think that’s going to happen – no money, for a start, and finding the time would be tough. But I’ll make sure the schools get prints of all the shots.

The plan is to have an exhibition – with the focus on raising money for the schools – early next year. With a bit of luck I’ve now taken all the images for my final major project, too – I just need to sell it to my tutors.

Upcoming events

Just to say I’m photographing at quite a few secular/skepticky events over the next month, in various cities. If anyone’s at / around any of these, it’d be cool to meet up. I’ll nag closer to the time, but I’m currently booked for:

  • Protest the Pope debate on the topic of “The Papal Visit should not be a State Visit”. AC Grayling and Peter Tatchell vs. Austen Ivereigh and Christopher Jamison.
    Wednesday 1st September. London. Conway Hall.
  • Come along to the Department of Health and become a registered practitioner of Old Wives’ Traditional Medicine. Sense about Science are highlighting the Department of Health’s proposed regulatory scheme for traditional medicine practitioners that doesn’t check whether the practitioner has any medical training, nor whether the medicine works.
    Wednesday 8th September. London. Department of Health, Whitehall.
  • Relief-o-matic comedy show, raising money for AIDS prevention and relief projects. Robin Ince, Ed Byrne, Natalie Haynes, Ben Goldacre, plus special guests.
    Monday 13th September. London. Bloomsbury Theatre.
  • Nope Pope: The Party. This is going to be an interesting one. Live music, dancing, deity-free weddings from ‘Pope Steve’, and fancy dress prizes.
    Friday 17th September. London. Conway Hall.
  • The big Protest the Pope march / rally. Starts Hyde Park at 1pm, then marches through Picadilly and Trafalgar Square to Downing Street.
    Saturday 18th September. London. Hyde Park.
  • BHA Liberal Democrat Conference Fringe Event. Discussion on ‘What role, if any, does faith have in the ‘Big Society’?’.
    Sunday 19th September. Liverpool. Liverpool Hilton.
  • BHA Labour Party Conference ‘No-prayer’ breakfast. Tea. Coffee. Secular pastries.
    Tuesday 28th September. Manchester. Manchester Central.
  • BHA Conservative Party Conference Event. A panel discussion on faith, multiculturalism and the ‘Big Society’, with Q&A.
    Tuesday 5th October. Birmingham. Hyatt Regency.
  • BHA Holyoake Lecture. Professor John Harris speaks on ‘Taking the “human” out of Humanism’.
    Thursday 21st October. Manchester. St Peter’s House, Precinct Centre.

How to look good on dating websites: ask a photographer

This is quite exciting: dating site OkCupid took half a million profile pictures, asked three million people to choose between two randomly chosen examples, and ran the stats on the resulting photos’ EXIF data.

I know!

No really. This is seriously interesting. Even taking into account my current state of mind. Because there’s lots of advice in photography, particularly when it comes to portraits, and it all seems valid and reasonable and important until you show a bunch of pictures to somebody and they immediately reach for the dodgy one. The one where you had no choice but to fire the flash in someone’s face. The one where you’re shooting a woman from below because some dude was in the way and that was your only option. The one where the subject is blurred, but it’s the only shot you have of that particular moment. And this obviously dubious photograph turns out to be someone’s favourite shot, because it captures something personal to them that you couldn’t possibly know. This seems to happen all the time. And you start to wonder how important all the advice really is.

I once saw a photographer’s email signature that said “photographers like composition, non-photographers like smiles”, and sometimes I wonder if that’s the best tip I’ve ever heard. What’s needed is some actual data. And OkCupid is the perfect place to look, as dating profiles are modern portraits’ raison d’être.

I’ll skip to the conclusion: it’s good news for photographers. Everything that should be true about portrait photography turns out to actually be true. OkCupid have proper analysis, but I’ll unashamedly yoink the headlines:

  • SLRs take more attractive photos than point & shoots. Camera phones are a long way behind1.
  • Direct flash sucks.
  • Low apertures (which blur the background) are seriously effective.
  • People look better during the golden hour – the soft, golden light just after sunrise and just before sunset.

None of which is a big surprise to portrait photographers, but this should be a big deal. The evidence up to now has always been anecdotal. Actual numbers = win. OkCupid’s methodology seems reasonable, with the standard internet-survey caveats, and the numbers are enormous. It’s nice when the humanities can play in grown-up world for a bit.

There’s lots more you could do with such a dataset. Another classic portrait tip is never, ever to use a wide-angle lens2 as it makes people’s noses look huge, amongst other distortions. This seems true, but I’d love to see the data. However, taking into account different sensor sizes would be a nightmare, and I can see why OkCupid didn’t go there. Similarly the actual distance from the lens might be interesting, as would white balance (does it make a difference if men have a reddish hue?) and colour analysis generally. I’d also like to see how this gels with the previous – much more surprising – analysis which showed the much derided ‘MySpace angle’ (taken by holding your camera above your head and looking sultry) is the most successful style of profile shot for women by a long way, even when you control for cleavage.

Also: I wonder if single photographers are ahead of the curve. Hmmm.

Anyway –  it seems that, on average, the classic rules of portraiture are valid. This obviously doesn’t mean anything for the quirky outlier photos that strike an unknown chord, but it suggests confirmation bias is perhaps playing a large role in my memory – I don’t remember the times when people like the photo that follows all the rules, because obviously they would. Portrait photographers can get a ‘safe’ shot from the old formulas – then you can start to play 🙂

…oh, and apparently iPhone users have more sex3. The numbers don’t lie, guys.

  1. well… []
  2. that said, wide-angle close-ups are incredibly common once you start looking, though they’re not necessarily as flattering []
  3. reads along graph to his age…traces upwards to the line…moves across to average number of sexual partners…oh fuck off []