This document outlines techniques for content-based image retrieval (CBIR) using color descriptors. It describes three color descriptor algorithms - columnar mean, average RGB method, and color moments. It evaluates these algorithms on a CBIR system and measures their performance in terms of precision, recall, and f-measure. The average RGB method achieved the highest average precision, recall, and f-measure. The document also discusses applying CBIR for retrieving images of marine invertebrates and compares different techniques for detecting features in images.