Summarized changelog:
2.13.1:
- Fix a bug on grayscale that made printing gray on white paper.
2.13:
- Added support for premultiplied alpha.
- CGATS parser can now deal with very long strings.
- Added thread safe code to get time.
- Added automatic linear space detection.
- Added cmsGetStageContextID function.
- Added cmsDetectRGBProfileGamma.
- Fixed mem leaks and out-of bounds accesses as reported by fuzzer.
Full changelogs available here for 2.13 and here for 2.13.1