Data preprocessing codes for volume rendering

These Python (version 3.x) codes are for calculation and adding of alpha value to RGB tomographic image datasets. The datasets are collections at National Museum of Nature and Science (NMNS), Tokyo, Japan (accession Nos. NMNS_DS00135_wl_01_0001.tif–4059.tif, NMNS_DS00155_wl_01 0001.tif–5001.tif, NMNS_DS00162_wl_01_0001.tif–NMNS_DS00162_wl_21_0020.tif). The output files by these codes are utilized for volume rendering using ParaView.