Simple Python Wrapper

import ctypes

fi = ctypes.windll.freeimage
fi.FreeImage_LoadU.restype = ctypes.c_void_p
fi.FreeImage_SaveU.argtypes = [ctypes.c_int, ctypes.c_void_p, ctypes.c_wchar_p, ctypes.c_int]

def getfmt(name):
  fmt = fi.FreeImage_GetFIFFromFilenameU(name)
  if fmt > -1:
    return fmt
  else:
    return fi.FreeImage_GetFileTypeU(name, 0)

def open(name, flag=0):
  fmt = getfmt(name)
  return fi.FreeImage_LoadU(fmt, name, flag)

def save(img, name, flag=0):
  fmt = getfmt(name)
  return fi.FreeImage_SaveU(fmt, img, name, flag)

x = open('text.png')
save(x, 'test.webp')