How to make a crowd color vote with Their phones

[dgerges]

How would you tackle this : - Having à Crowd of 600 sitting - let them chose à color on their phone (4 possibilités) - have people show their phones - take à picture of the audience and count the Colors

Does it seem feasible ? Where would you start for the counting ?

[celticninja]

Make an app with the colours on. People download the app and enter a code to join the audience. You count the colour selections reported by the app not from a picture. You can still get them to hold up the colours because sometimes you can tell at a glance the most common colour.