def METHOD_NAME(self, img_feat):
    _, _, h, w = img_feat.shape
    self_mask = F.one_hot(
        paddle.reshape(paddle.arange(h * w), (h, w)),
        num_classes=int(h * w))
    self_mask = paddle.transpose(self_mask, (2, 0, 1))
    self_mask = paddle.reshape(self_mask, (1, h * w, h, w))
    return self_mask * (-1e4)