libpng-apng v1.0.0+apng.1.6.37 (2021-06-23T11:37:31Z)

PNG_FILTER_UP

Undocumented in source but is binding to C. You might be able to learn more by searching the web for its name.

version(!PNG_VERSION_INFO_ONLY)

extern (C)

enum PNG_FILTER_UP = 0x20;

Meta