Ying Liu Dengsheng Zhang Guojun Lu Wei-Ying Ma Region-Based Image Retrieval with Perceptual Colors. 931-938 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3332&spage=931 2004 conf/pcm/2004-2 PCM (2) db/conf/pcm/pcm2004-2.html#LiuZLM04