This document describes a semi-supervised collaborative image retrieval system using relevance feedback. The system aims to improve the performance of content-based image retrieval (CBIR) systems by reducing the number of images a user must label during relevance feedback. It uses a semi-supervised approach where the user only needs to label a few of the most informative images. These labeled images are used to train a support vector machine (SVM) classifier. The images in the database are then resorted based on a new similarity metric determined by the classifier. The system provides iteratively improved retrieval results until the user is satisfied, thereby bridging the semantic gap between low-level visual features and high-level semantics.