Can IrfanView manipulate an image buffer?

It can manipulate images stored on file system, but can it take in an image buffer?

Else, what other options or fre开发者_如何学运维e SDKs can I use to manipulate an image buffer? In particular, rotation.

Take a look at ImageMagick -- it can take a buffer directly.

You didn't say what language/framework you use. For .NET look at Atalasoft's DotImage Photo, which is free (disclaimer: I work at Atalasoft).