Did you know that M&M’s are named after Marilyn Monroe? Sorry, that’s not actually true. Even so, the initials make the chocolate beans a particularly appropriate medium for representation of the delectable Hollywood starlet. If you want to turn any image into a pixellated M&M portrait then you can do so on this website by Tim Chartier and Shane Macnamara of Davidson College, North Carolina. The site uses only the six classic M&M’s colours and lets you choose the number of M&M’s in the image: here I chose a row length of 30.

The site also gives you the option of turning an image into a mosaic of Smarties. I think Smartie Marilyn is much more faithful to the aesthetic of Warhol’s original. The Smartie colours are more garish and colourful - and there are eight of them compared to six with M&M’s. Here again I have chosen a row of length 30. The process the site uses is to divide the original image into small squares, in this case 30 of them across. Each square is represented by three numbers (r, g, b) where r is the average amount of red, g the average of green and b the average of blue in that square.

Once the computer has the triplet (r, g, b) of a square, an algorithm calculates which Smartie/M&M’s colour that square is closest to, and replaces the square by a chocolate of that colour. The method used imagines (r, g, b) as 3D coordinates. Each Smarties/M&M’s colour is also a fixed triplet of 3D coordinates. The nearest colour is the one of closest distance in 3D space, which is calculated using Pythagoras’s Theorem. Here is Marilyn in a row of only 20 Smarties. If you squint your eyes, or hold the image at a distance you can still see her face pretty clearly.

And here she is with a row of only 10 Smarties. You can definitely make out that it is a face. But you reeeeally need to squint your eyes this time or have the image at a further distance.

Another American celebrity whose name lends itself to candy colouring. Ladies and gentlemen: Eminem in M&M’s!

It’s fine. You can call me a Smartie pants. (Joke not intended for Americans. You don’t understand Smarties. Or pants.)

To counterweight the free promotion I am giving two well-known brands, here is Choco-Che. Hasta la pixelacion siempre.

And a Smartie phone.

M&MMM donuts! For more information on the math behind the algorithm that creates the mosaics, it’s in Tim Chartier’s Math Bytes.

S-M-R-T. Thank you and goodnight. To stay in touch with this blog please follow me @alexbellos on Twitter or like my Facebook page.