Perceived image similarity and quantization resolution

Color quantization is a key step in content-based image retrieval based on color histograms and is critical to the retrieval performance. An important factor related to color quantization is the quantization resolution. It is important to empirically evaluate how resolution levels affect human perceptions of image similarity. A laboratory study was conducted to analyze the effect of different resolution levels on human judgment of image similarity. The results show that the impact of quantization resolutions on perceived image similarity is not linear. In fact, a logarithm relationship fits the data very well. Furthermore, there is a surprising result that the objective measure of colorloss can predict perceived image quite well. The study provides accurate data for content-based image retrieval researchers to decide on the tradeoff between processing speed (which is affected by the choice of resolution level) and perceived image similarity.