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Diffstat (limited to 'webrtc/modules/video_processing/util/skin_detection.cc')
-rw-r--r-- | webrtc/modules/video_processing/util/skin_detection.cc | 65 |
1 files changed, 65 insertions, 0 deletions
diff --git a/webrtc/modules/video_processing/util/skin_detection.cc b/webrtc/modules/video_processing/util/skin_detection.cc new file mode 100644 index 0000000000..bf631ce2f6 --- /dev/null +++ b/webrtc/modules/video_processing/util/skin_detection.cc @@ -0,0 +1,65 @@ +/* + * Copyright (c) 2015 The WebRTC project authors. All Rights Reserved. + * + * Use of this source code is governed by a BSD-style license + * that can be found in the LICENSE file in the root of the source + * tree. An additional intellectual property rights grant can be found + * in the file PATENTS. All contributing project authors may + * be found in the AUTHORS file in the root of the source tree. + */ + +#include <limits.h> +#include <math.h> + +#include "webrtc/modules/video_processing/util/skin_detection.h" + +namespace webrtc { + +// Fixed-point skin color model parameters. +static const int skin_mean[2] = {7463, 9614}; // q6 +static const int skin_inv_cov[4] = {4107, 1663, 1663, 2157}; // q16 +static const int skin_threshold = 1570636; // q18 + +// Thresholds on luminance. +static const int y_low = 20; +static const int y_high = 220; + +// Evaluates the Mahalanobis distance measure for the input CbCr values. +static int EvaluateSkinColorDifference(int cb, int cr) { + const int cb_q6 = cb << 6; + const int cr_q6 = cr << 6; + const int cb_diff_q12 = (cb_q6 - skin_mean[0]) * (cb_q6 - skin_mean[0]); + const int cbcr_diff_q12 = (cb_q6 - skin_mean[0]) * (cr_q6 - skin_mean[1]); + const int cr_diff_q12 = (cr_q6 - skin_mean[1]) * (cr_q6 - skin_mean[1]); + const int cb_diff_q2 = (cb_diff_q12 + (1 << 9)) >> 10; + const int cbcr_diff_q2 = (cbcr_diff_q12 + (1 << 9)) >> 10; + const int cr_diff_q2 = (cr_diff_q12 + (1 << 9)) >> 10; + const int skin_diff = + skin_inv_cov[0] * cb_diff_q2 + skin_inv_cov[1] * cbcr_diff_q2 + + skin_inv_cov[2] * cbcr_diff_q2 + skin_inv_cov[3] * cr_diff_q2; + return skin_diff; +} + +bool MbHasSkinColor(const uint8_t* y_src, + const uint8_t* u_src, + const uint8_t* v_src, + const int stride_y, + const int stride_u, + const int stride_v, + const int mb_row, + const int mb_col) { + const uint8_t* y = y_src + ((mb_row << 4) + 8) * stride_y + (mb_col << 4) + 8; + const uint8_t* u = u_src + ((mb_row << 3) + 4) * stride_u + (mb_col << 3) + 4; + const uint8_t* v = v_src + ((mb_row << 3) + 4) * stride_v + (mb_col << 3) + 4; + // Use 2x2 average of center pixel to compute skin area. + uint8_t y_avg = (*y + *(y + 1) + *(y + stride_y) + *(y + stride_y + 1)) >> 2; + uint8_t u_avg = (*u + *(u + 1) + *(u + stride_u) + *(u + stride_u + 1)) >> 2; + uint8_t v_avg = (*v + *(v + 1) + *(v + stride_v) + *(v + stride_v + 1)) >> 2; + // Ignore MB with too high or low brightness. + if (y_avg < y_low || y_avg > y_high) + return false; + else + return (EvaluateSkinColorDifference(u_avg, v_avg) < skin_threshold); +} + +} // namespace webrtc |