8f9902a0ff
BUG=webrtc:5255 Review URL: https://codereview.webrtc.org/1466763002 Cr-Commit-Position: refs/heads/master@{#10800}
72 lines
2.7 KiB
C++
Executable File
72 lines
2.7 KiB
C++
Executable File
/*
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* Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include <limits.h>
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#include <math.h>
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#include "webrtc/modules/video_processing/util/skin_detection.h"
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namespace webrtc {
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// Fixed-point skin color model parameters.
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static const int skin_mean[2] = {7463, 9614}; // q6
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static const int skin_inv_cov[4] = {4107, 1663, 1663, 2157}; // q16
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static const int skin_threshold = 1570636; // q18
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// Thresholds on luminance.
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static const int y_low = 20;
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static const int y_high = 220;
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// Evaluates the Mahalanobis distance measure for the input CbCr values.
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static int EvaluateSkinColorDifference(int cb, int cr) {
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const int cb_q6 = cb << 6;
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const int cr_q6 = cr << 6;
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const int cb_diff_q12 = (cb_q6 - skin_mean[0]) * (cb_q6 - skin_mean[0]);
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const int cbcr_diff_q12 = (cb_q6 - skin_mean[0]) * (cr_q6 - skin_mean[1]);
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const int cr_diff_q12 = (cr_q6 - skin_mean[1]) * (cr_q6 - skin_mean[1]);
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const int cb_diff_q2 = (cb_diff_q12 + (1 << 9)) >> 10;
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const int cbcr_diff_q2 = (cbcr_diff_q12 + (1 << 9)) >> 10;
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const int cr_diff_q2 = (cr_diff_q12 + (1 << 9)) >> 10;
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const int skin_diff =
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skin_inv_cov[0] * cb_diff_q2 + skin_inv_cov[1] * cbcr_diff_q2 +
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skin_inv_cov[2] * cbcr_diff_q2 + skin_inv_cov[3] * cr_diff_q2;
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return skin_diff;
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}
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bool MbHasSkinColor(const uint8_t* y_src,
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const uint8_t* u_src,
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const uint8_t* v_src,
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const int stride_y,
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const int stride_u,
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const int stride_v,
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const int mb_row,
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const int mb_col) {
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const uint8_t* y =
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y_src + ((mb_row << 4) + 8) * stride_y + (mb_col << 4) + 8;
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const uint8_t* u =
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u_src + ((mb_row << 3) + 4) * stride_u + (mb_col << 3) + 4;
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const uint8_t* v =
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v_src + ((mb_row << 3) + 4) * stride_v + (mb_col << 3) + 4;
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// Use 2x2 average of center pixel to compute skin area.
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uint8_t y_avg =
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(*y + *(y + 1) + *(y + stride_y) + *(y + stride_y + 1)) >> 2;
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uint8_t u_avg =
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(*u + *(u + 1) + *(u + stride_u) + *(u + stride_u + 1)) >> 2;
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uint8_t v_avg =
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(*v + *(v + 1) + *(v + stride_v) + *(v + stride_v + 1)) >> 2;
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// Ignore MB with too high or low brightness.
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if (y_avg < y_low || y_avg > y_high)
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return false;
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else
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return (EvaluateSkinColorDifference(u_avg, v_avg) < skin_threshold);
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}
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} // namespace webrtc
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