Pixel Portraits: Appearing at London & Paris Fashion Week

By Stephen Jayna, 15th May 2009

Rowan Mersh's Pixel Portraits is picking out faces of passers-by and projecting them — in photomosaic form — onto a shop window near you.


Background

Pixel Portraits ran live 24 hours a day for a 10 day period at the beginning of October 2008 at Maria Luisa in Paris. Capturing images of passers-by using face recognition technology over 1000 unique Pixel Portraits were generated during the course of the show. Read more at Rowan's website.

The scene at Maria Luisa, Paris The Mobile Photo Booth in Maria Luisa A Pixel Portrait The Mobile Photo Booth in Feathers, Knightsbridge The scene at Feathers, Knightsbridge A Pixel Portrait Yours truely Yours truely, close up Metapixel at Work OpenCV at Work Window Vinyl In French OpenCV at Work, Window Vinyl in English The scene at Feathers from across the road
4 of 13 Images Shown, Click On Any Image To See More

Window Shopping

First let me set the scene. You find yourself window shopping in the streets of Paris during Fashion Week. How de rigueur. Coming across a window dominated by a large projection screen with what can only be described as a mobile photo booth hanging besides it you peer inquisitively in.

By now you notice a countdown has been initiated and that your photo is about to be taken. Moments later — and perhaps to your horror — your face is displayed on the projection screen, albiet in photomosaic form. The photo that was taken has been used thousands of time to make up the now Pop Art styled projection. I guess it makes a change from having a bunch of well dressed dummies staring back at you.

How It Was Done: In Brief

Hardware

First things first, let me run you through the hardware setup. The mobile photo booth: a Sony Vaio laptop (mostly because it was capable of opening out flat) and a webcam (a Philips SPC 900NC — superb in low light).

The laptop's VGA out was connected via a 15-metre long cable to the projector. The nice thing here is that we were able to drive the laptop screen and the VGA out seperately as a dual-head setup.

Face Recognition: OpenCV for Artists

The simplest way for us to interact with passers-by was to detect the presence of a face automatically in order to know when to take a photo. We considered other options including buttons and pressure pads but this seemed far cleaner, and frankly more impressive. If we could get it to work consistently! With a target shown on the screen of the photo booth the user is implored to line up their face so it sits roughly within the target area and then to wait for the countdown to commence.

OpenCV is a real-time image processing system that allows you to — amongst other things — recognise the presence of a human face and track its movement. This video shows a basic example of face tracking. That isn't me in the video I hasten to add.

So there you are posing beautifully, or perhaps just dutifully, and 3...2...1 — FLASH — the so far unadulterated photo is now shown on the photo booth's screen. All the while Metapixel is processing your visage into something to be shown on the all together more impressive projection screen for the assembled masses.

Photomosaics: Metapixel

Metapixel is a program for generating photomosaics and was used to create our final effect. You can see some of the ones we made in the picture gallery towards the top of this article. Metapixel itself allows you to feed in an arbitary number of source images which are used to create a photomosaic. In our case we fed in the same source image but slightly varied in terms of brightness, contrast and orientation to give us enough differing images for the effect to work.

And To Sum Up

So there you have it. Combine a projector, a camera and a computer and there's fun to be had. Here are a smattering of variations on the theme:

You get the idea anyway, YouTube is awash with interesting examples. Naturally Everita is keen to take on such projects.


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