Define file.s, file2.s, image = 3
file = OpenFileRequester("Select source image file", "", "PPM image (*.ppm)|*.ppm", 0)
If file And LCase(GetExtensionPart(file)) = "ppm"
  LoadImagePPM(image, file)
  ImageGrayout(image)
  file2 = Left(file, Len(file) - Len(GetExtensionPart(file))) + "_grayscale." + GetExtensionPart(file)
  SaveImageAsPPM(image, file2, 1)
EndIf