How to count Pencil Crayon Colors in ImageJ

[cmrober2]

Hi,

I have an odd task that I am trying to do. Our project has 3100 pieces of art drawn by 4th grade students and we are trying to understand their perceptions of water use and water scarcity now and in the future. We would like to determine how often colors we associate with plentiful water (green vegetation etc.) and clean water (blue) contrast with dirty water and dead vegetation (browns and reds).

I've tried using a variety of color pixel counters, but they are all too advanced for our study and count too many different shades to be of use.

Is there a way to count basic colors? And find out the ratio of how often they occur in an image?

Thanks

Chris