def METHOD_NAME(self, path, ext, operator):
    if operator == "resize":
        return 'NG'
    elif operator == "save":
        return 'OK'
    else:
        if ext == '.png':
            f = path if hasattr(path, "read") else open(path, "rb")
            r = png.Reader(file=f)
            width, height, pixels, metadata = r.asDirect()
            f.seek(0)
            bit_depth = metadata.get("bitdepth")
            if bit_depth not in [8, 16]:
                return "NG"
            else:
                return "Recommended"
        else:
            return "NG"