ORAC, my Optical Reader of Accurate Colour, is a device that will (all being well) remove or at least ameliorate the issue of the inherent variability of human colour vision. Having its own light source, it will give a consistent reading of colour measurement (in RGB values), rather than being effected by light levels.

The prototype is made from an Arduino board, and an Adafruit TCS34725 colour sensor. Theoretically it’s a surprisingly powerful colour sensor that will give accurate readings in all light levels due to its inbuilt LED light.

Currently it is being about as cooperative as its namesake, so, a demonstration is to follow.

UPDATE 3.12.15

I’m driving down to Bournemouth for a supervisory meeting on Monday, so naturally I wanted ORAC up and running to show it off. The device had other plans in mind. My first colour sensor chip was a dud, it turns out. Now I have a replacement, and I’m still having trouble – looks like a connection issue, so I’m going into the workshop tomorrow to resolder and hope for the best.

Currently, when I run the sketch to analyse colour, ORAC goes a bit Rolling Stones on me and just sees everything as – black. Hmm. Hopefully *not* an omen of how my meeting is going to go.

UPDATE 4.12.15

So workshop bound today I took my little prototype and soldered it together. I tested all my wiring and double checked my code. And so, this evening – it lives!

I recorded a short (slightly wobbly) video of it in action, partially as a dry run for recording something a little more technical down the line, but also to have something to show people without carrying ORAC around with me – it’s still a prototype so fragile, until I develop it into a standalone unit in its own case.

With the obligatory “is that really what my voice sounds like?” here it is…

UPDATE 08.01.2017

Well it’s been a busy year for ORAC and I. He’s so much more than a simple tool to this project – I’ve been exploring the theoretical implications of his design and use, and looking at ways I can closer understand the material agency of the stones themselves by using ORAC as a recording device rather than estimating colour myself.

Technically speaking, there have been several updates – tweaks to programming to improve the accuracy of colour readings, an LCD screen, and batteries mean he’s now a mobile unit. Progress did not go well at first (why is the screen in gibberish? I scream at 4am…) but now ORAC is a fully functional field device.

I debuted him in the spring during the NSG field trip to Anglesey, then at the Calderstones in July, and recently in the Avebury landscape. He now also has a daylight filter so I can take both LED based readings and ones closer to true daylight, and a wrist strap for ease of use; currently, it’s still housed in a Forrero Rocher box. Miniaturisation to follow!


I’ll soon be presenting papers on the theoretical implications of ORAC – at CAA Atlanta in March 2017, and a poster at Bournemouth’s postgraduate conference in the same month. I’ll update here once I can share PDFs of these papers.

UPDATE 24.07.17

ORAC has had many holidays and trips over the course of this year – to Stonehenge for a night of recording those most contentious and marketable of Neolithic stones, and trekking across Europe for a trip encompassing the Netherlands, Denmark, and Sweden.


ORAC gets to touch Stonehenge, the lucky thing.

I’m sorry to say that he is now somewhat worse for wear, and in for repairs. There’s still a trip to Ireland in the works before he can retire.

Somewhat poorly, ready for repairs.


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