Replace images by text

I have a single column with more than 200.000 cells. In each cell there is a small image obtained from a website. There are four different images: red, orange, yellow and green . What I need is to replace all equal images by an equal string, such as (red square) =Q4, (orange square) =Q3 and so on, or, at least, place a string for each image type in an adjacent cell

Any advice will be very welcome. Thank you in advance.

Jorge.