FastDeploy/fastdeploy/vision/utils/face_align.cc

// Copyright (c) 2022 PaddlePaddle Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// reference:
// https://github.com/deepinsight/insightface/blob/master/recognition/_tools_/cpp_align/face_align.h
#include "fastdeploy/vision/utils/utils.h"

namespace fastdeploy {
namespace vision {
namespace utils {

cv::Mat MeanAxis0(const cv::Mat& src) {
  int num = src.rows;
  int dim = src.cols;
  cv::Mat output(1, dim, CV_32F);
  for (int i = 0; i < dim; i++) {
    float sum = 0;
    for (int j = 0; j < num; j++) {
      sum += src.at<float>(j, i);
    }
    output.at<float>(0, i) = sum / num;
  }
  return output;
}

cv::Mat ElementwiseMinus(const cv::Mat& A, const cv::Mat& B) {
  cv::Mat output(A.rows, A.cols, A.type());
  assert(B.cols == A.cols);
  if (B.cols == A.cols) {
    for (int i = 0; i < A.rows; i++) {
      for (int j = 0; j < B.cols; j++) {
        output.at<float>(i, j) = A.at<float>(i, j) - B.at<float>(0, j);
      }
    }
  }
  return output;
}

cv::Mat VarAxis0(const cv::Mat& src) {
  cv::Mat temp_ = ElementwiseMinus(src, MeanAxis0(src));
  cv::multiply(temp_, temp_, temp_);
  return MeanAxis0(temp_);
}

int MatrixRank(cv::Mat M) {
  cv::Mat w, u, vt;
  cv::SVD::compute(M, w, u, vt);
  cv::Mat1b non_zero_singular_values = w > 0.0001;
  int rank = countNonZero(non_zero_singular_values);
  return rank;
}

cv::Mat SimilarTransform(cv::Mat& dst, cv::Mat& src) {
  int num = dst.rows;
  int dim = dst.cols;
  cv::Mat src_mean = MeanAxis0(dst);
  cv::Mat dst_mean = MeanAxis0(src);
  cv::Mat src_demean = ElementwiseMinus(dst, src_mean);
  cv::Mat dst_demean = ElementwiseMinus(src, dst_mean);
  cv::Mat A = (dst_demean.t() * src_demean) / static_cast<float>(num);
  cv::Mat d(dim, 1, CV_32F);
  d.setTo(1.0f);
  if (cv::determinant(A) < 0) {
    d.at<float>(dim - 1, 0) = -1;
  }
  cv::Mat T = cv::Mat::eye(dim + 1, dim + 1, CV_32F);
  cv::Mat U, S, V;
  cv::SVD::compute(A, S, U, V);
  int rank = MatrixRank(A);
  if (rank == 0) {
    assert(rank == 0);
  } else if (rank == dim - 1) {
    if (cv::determinant(U) * cv::determinant(V) > 0) {
      T.rowRange(0, dim).colRange(0, dim) = U * V;
    } else {
      int s = d.at<float>(dim - 1, 0) = -1;
      d.at<float>(dim - 1, 0) = -1;

      T.rowRange(0, dim).colRange(0, dim) = U * V;
      cv::Mat diag_ = cv::Mat::diag(d);
      cv::Mat twp = diag_ * V;  // np.dot(np.diag(d), V.T)
      cv::Mat B = cv::Mat::zeros(3, 3, CV_8UC1);
      cv::Mat C = B.diag(0);
      T.rowRange(0, dim).colRange(0, dim) = U * twp;
      d.at<float>(dim - 1, 0) = s;
    }
  } else {
    cv::Mat diag_ = cv::Mat::diag(d);
    cv::Mat twp = diag_ * V.t();  // np.dot(np.diag(d), V.T)
    cv::Mat res = U * twp;        // U
    T.rowRange(0, dim).colRange(0, dim) = -U.t() * twp;
  }
  cv::Mat var_ = VarAxis0(src_demean);
  float val = cv::sum(var_).val[0];
  cv::Mat res;
  cv::multiply(d, S, res);
  float scale = 1.0 / val * cv::sum(res).val[0];
  T.rowRange(0, dim).colRange(0, dim) =
      -T.rowRange(0, dim).colRange(0, dim).t();
  cv::Mat temp1 = T.rowRange(0, dim).colRange(0, dim);  // T[:dim, :dim]
  cv::Mat temp2 = src_mean.t();                         // src_mean.T
  cv::Mat temp3 = temp1 * temp2;  // np.dot(T[:dim, :dim], src_mean.T)
  cv::Mat temp4 = scale * temp3;
  T.rowRange(0, dim).colRange(dim, dim + 1) = -(temp4 - dst_mean.t());
  T.rowRange(0, dim).colRange(0, dim) *= scale;
  return T;
}

std::vector<cv::Mat> AlignFaceWithFivePoints(
    cv::Mat& image, FaceDetectionResult& result,
    std::vector<std::array<float, 2>> std_landmarks,
    std::array<int, 2> output_size) {
  FDASSERT(std_landmarks.size() == 5, "The landmarks.size() must be 5.")
  FDASSERT(!image.empty(), "The input_image can't be empty.")
  std::vector<cv::Mat> output_images;
  output_images.reserve(result.scores.size());
  if (result.boxes.empty()) {
    FDWARNING << "The result is empty." << std::endl;
    return output_images;
  }

  cv::Mat src(5, 2, CV_32FC1, std_landmarks.data());
  for (int i = 0; i < result.landmarks.size(); i += 5) {
    cv::Mat dst(5, 2, CV_32FC1, result.landmarks.data() + i);
    cv::Mat m = SimilarTransform(dst, src);
    cv::Mat map_matrix;
    cv::Rect map_matrix_r = cv::Rect(0, 0, 3, 2);
    cv::Mat(m, map_matrix_r).copyTo(map_matrix);
    cv::Mat cropped_image_aligned;
    cv::warpAffine(image, cropped_image_aligned, map_matrix,
                   {output_size[0], output_size[1]});
    if (cropped_image_aligned.empty()) {
      FDWARNING << "croppedImageAligned is empty." << std::endl;
    }
    output_images.emplace_back(cropped_image_aligned);
  }
  return output_images;
}
}  // namespace utils
}  // namespace vision
}  // namespace fastdeploy