Racket scheme read write png files

In Racket scheme are th开发者_Python百科ere any libraries that allow you to read in a png, alter the image and write it back to disk? Failing png any other common image formats.

There is support for PNGs. You can load them as a bitmap and then write them out with the save-file method.

There's at least built-in support for GIF: http://docs.racket-lang.org/file/gif.html