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PNG is designed to work well in on-line viewing applications, such as the World Wide Web, and so it is fully streamable with a progressive display option. It can also contain gamma and chromaticity data for improved color matching on heterogenous platforms.
PNG is intended to be both highly extensible and highly interchangeable. Although incompatible private extensions are possible, it is expected that all PNG decoders will be able to read essentially all PNG files.
The proposed Internet Media Type image/png is defined by this specification.