ISO/IEC 15948:2004 specifies a datastream and an associated file format, Portable Network Graphics (PNG, pronounced "ping"), for a lossless, portable, compressed individual computer graphics image transmitted across the Internet. Indexed-colour, greyscale, and truecolour images are supported, with optional transparency. Sample depths range from 1 to 16 bits. PNG is fully streamable with a progressive display option. It is robust, providing both full file integrity checking and simple detection of common transmission errors. PNG can store gamma and chromaticity data as well as a full ICC colour profile for accurate colour matching on heterogenous platforms. ISO/IEC 15948:2004 defines the Internet Media type "image/png". The datastream and associated file format have value outside of the main design goal.