说起红眼算法,这个话题非常古老了。
百度百科上的描述:
“红眼”一般是指在人物摄影时,当闪光灯照射到人眼的时候,瞳孔放大而产生的视网膜泛红现象。
由于红眼现象的程度是根据拍摄对象色素的深浅决定的,如果拍摄对象的眼睛颜色较深,红眼现象便不会特别明显。
“红眼”也指传染性结膜炎。
近些年好像没有看到摄影会出现这样的情况,毕竟科技发展迅速。
记得最早看到红眼移除算法是在ACDSee 这个看图软件的编辑功能区。
当然,当时ACDSee 也没有能力做到自动去红眼,也需要进行手工操作。
红眼移除不难,其实就是把眼睛区域的颜色修正一下。
但是难就难在修复之后,不要显得太过突兀,或者破坏眼睛周围的颜色 。
这就有点难办了。
当然其实最简单的思路,就是转色域空间处理后再转回RGB。
记得在2015年的时候,
曾经一度想要寻找红眼移除过度自然的算法思路,
当时仅仅是好奇,想要学习之。
直到2016年,在一个Delphi 图像控件的源码里看到了一个红颜移除算法函数。
把代码转写成C之后验证了一下,效果不错,过度很自然。
貌似好像有点暴露年龄了,
俺也曾经是Delphi程序员来的,无比怀念Delphi7。
贴上红眼算法的Delphi源码:
procedure _IERemoveRedEyes(bitmap: TIEBitmap; fSelx1, fSely1, fSelx2, fSely2: integer; fOnProgress: TIEProgressEvent; Sender: TObject); var row, col: integer; nrv, bluf, redq, powr, powb, powg: double; per1: double; px: PRGB; begin fSelX2 := imin(fSelX2, bitmap.Width); dec(fSelX2); fSelY2 := imin(fSelY2, bitmap.Height); dec(fSelY2); per1 := 100 / (fSelY2 - fSelY1 + 0.5); for row := fSelY1 to fSelY2 do begin px := bitmap.Scanline[row]; for col := fSelX1 to fSelX2 do begin nrv := px^.g + px^.b; if nrv < 1 then nrv := 1; if px^.g > 1 then bluf := px^.b / px^.g else bluf := px^.b; bluf := dMax(0.5, dMin(1.5, Sqrt(bluf))); redq := (px^.r / nrv) * bluf; if redq > 0.7 then begin powr := 1.775 - (redq * 0.75 + 0.25); if powr < 0 then powr := 0; powr := powr * powr; powb := 1 - (1 - powr) / 2; powg := 1 - (1 - powr) / 4; with px^ do begin r := Round(powr * r); b := Round(powb * b); g := Round(powg * g); end; end; inc(px); end; if assigned(fOnProgress) then fOnProgress(Sender, trunc(per1 * (row - fSelY1 + 1))); Application.ProcessMessages; end; end;
非常非常简单的代码。
但是思路很巧妙。
不多说,各位看官自己品味一下。
先上个效果图:
说明下本文背景前提:
人脸识别暂时采用MTCNN,示例不考虑判断是否存在红眼。
人脸检测部分,详情见博文《MTCNN人脸检测 附完整C++代码》
算法步骤:
检测人脸,对齐得到人脸五个特征点。
算出两眼球之间的距离,
估算眼球的大概大小,
(示例代码采用 两眼球之间的距离的九分之一)
计算相应的半径,
按圆形修复眼球颜色即可。
完整示例代码献上:
#include "mtcnn.h" #include "browse.h" #define USE_SHELL_OPEN #ifndef nullptr #define nullptr 0 #endif #if defined(_MSC_VER) #define _CRT_SECURE_NO_WARNINGS #include <windows.h> #else #include <unistd.h> #endif #define STB_IMAGE_STATIC #define STB_IMAGE_IMPLEMENTATION #include "stb_image.h" //ref:https://github.com/nothings/stb/blob/master/stb_image.h #define TJE_IMPLEMENTATION #include "tiny_jpeg.h" //ref:https://github.com/serge-rgb/TinyJPEG/blob/master/tiny_jpeg.h #include <stdint.h> #include "timing.h" char saveFile[1024]; unsigned char *loadImage(const char *filename, int *Width, int *Height, int *Channels) { return stbi_load(filename, Width, Height, Channels, 0); } void saveImage(const char *filename, int Width, int Height, int Channels, unsigned char *Output) { memcpy(saveFile + strlen(saveFile), filename, strlen(filename)); *(saveFile + strlen(saveFile) + 1) = 0; //保存为jpg if (!tje_encode_to_file(saveFile, Width, Height, Channels, true, Output)) { fprintf(stderr, "save JPEG fail.\n"); return; } #ifdef USE_SHELL_OPEN browse(saveFile); #endif } void splitpath(const char *path, char *drv, char *dir, char *name, char *ext) { const char *end; const char *p; const char *s; if (path[0] && path[1] == ‘:‘) { if (drv) { *drv++ = *path++; *drv++ = *path++; *drv = ‘\0‘; } } else if (drv) *drv = ‘\0‘; for (end = path; *end && *end != ‘:‘;) end++; for (p = end; p > path && *--p != ‘\\‘ && *p != ‘/‘;) if (*p == ‘.‘) { end = p; break; } if (ext) for (s = end; (*ext = *s++);) ext++; for (p = end; p > path;) if (*--p == ‘\\‘ || *p == ‘/‘) { p++; break; } if (name) { for (s = p; s < end;) *name++ = *s++; *name = ‘\0‘; } if (dir) { for (s = path; s < p;) *dir++ = *s++; *dir = ‘\0‘; } } void getCurrentFilePath(const char *filePath, char *saveFile) { char drive[_MAX_DRIVE]; char dir[_MAX_DIR]; char fname[_MAX_FNAME]; char ext[_MAX_EXT]; splitpath(filePath, drive, dir, fname, ext); size_t n = strlen(filePath); memcpy(saveFile, filePath, n); char *cur_saveFile = saveFile + (n - strlen(ext)); cur_saveFile[0] = ‘_‘; cur_saveFile[1] = 0; } void drawPoint(unsigned char *bits, int width, int depth, int x, int y, const uint8_t *color) { for (int i = 0; i < min(depth, 3); ++i) { bits[(y * width + x) * depth + i] = color[i]; } } void drawLine(unsigned char *bits, int width, int depth, int startX, int startY, int endX, int endY, const uint8_t *col) { if (endX == startX) { if (startY > endY) { int a = startY; startY = endY; endY = a; } for (int y = startY; y <= endY; y++) { drawPoint(bits, width, depth, startX, y, col); } } else { float m = 1.0f * (endY - startY) / (endX - startX); int y = 0; if (startX > endX) { int a = startX; startX = endX; endX = a; } for (int x = startX; x <= endX; x++) { y = (int)(m * (x - startX) + startY); drawPoint(bits, width, depth, x, y, col); } } } void drawRectangle(unsigned char *bits, int width, int depth, int x1, int y1, int x2, int y2, const uint8_t *col) { drawLine(bits, width, depth, x1, y1, x2, y1, col); drawLine(bits, width, depth, x2, y1, x2, y2, col); drawLine(bits, width, depth, x2, y2, x1, y2, col); drawLine(bits, width, depth, x1, y2, x1, y1, col); } #ifndef MAX #define MAX(a, b) (((a) > (b)) ? (a): (b)) #endif #ifndef MIN #define MIN(a, b) (((a) > (b)) ? (b): (a)) #endif unsigned char ClampToByte(int Value) { return ((Value | ((signed int) (255 - Value) >> 31)) & ~((signed int) Value >> 31)); } int Clamp(int Value, int Min, int Max) { if (Value < Min) return Min; else if (Value > Max) return Max; else return Value; } void RemoveRedEyes(unsigned char *input, unsigned char *output, int width, int height, int depth, int CenterX, int CenterY, int Radius) { if (depth < 3) return; if ((input == nullptr) || (output == nullptr)) return; if ((width <= 0) || (height <= 0)) return; int Left = Clamp(CenterX - Radius, 0, width); int Top = Clamp(CenterY - Radius, 0, height); int Right = Clamp(CenterX + Radius, 0, width); int Bottom = Clamp(CenterY + Radius, 0, height); int PowRadius = Radius * Radius; for (int Y = Top; Y < Bottom; Y++) { unsigned char *in_scanline = input + Y * width * depth + Left * depth; unsigned char *out_scanline = output + Y * width * depth + Left * depth; int OffsetY = Y - CenterY; for (int X = Left; X < Right; X++) { int OffsetX = X - CenterX; int dis = OffsetX * OffsetX + OffsetY * OffsetY; if (dis <= PowRadius) { float bluf = 0; int Red = in_scanline[0]; int Green = in_scanline[1]; int Blue = in_scanline[2]; int nrv = Blue + Green; if (nrv < 1) nrv = 1; if (Green > 1) bluf = (float) Blue / Green; else bluf = (float) Blue; bluf = MAX(0.5f, MIN(1.5f, sqrt(bluf))); float redq = (float) Red / nrv * bluf; if (redq > 0.7f) { float powr = 1.775f - (redq * 0.75f + 0.25f); if (powr < 0) powr = 0; powr = powr * powr; float powb = 0.5f + powr * 0.5f; float powg = 0.75f + powr * 0.25f; out_scanline[0] = ClampToByte(powr * Red + 0.5f); out_scanline[1] = ClampToByte(powg * Green + 0.5f); out_scanline[2] = ClampToByte(powb * Blue + 0.5f); } } in_scanline += depth; out_scanline += depth; } } } int main(int argc, char **argv) { printf("mtcnn face detection\n"); printf("blog:http://cpuimage.cnblogs.com/\n"); if (argc < 2) { printf("usage: %s model_path image_file \n ", argv[0]); printf("eg: %s ../models ../sample.jpg \n ", argv[0]); printf("press any key to exit. \n"); getchar(); return 0; } const char *model_path = argv[1]; char *szfile = argv[2]; getCurrentFilePath(szfile, saveFile); int Width = 0; int Height = 0; int Channels = 0; unsigned char *inputImage = loadImage(szfile, &Width, &Height, &Channels); if (inputImage == nullptr || Channels != 3) return -1; ncnn::Mat ncnn_img = ncnn::Mat::from_pixels(inputImage, ncnn::Mat::PIXEL_RGB, Width, Height); std::vector<Bbox> finalBbox; MTCNN mtcnn(model_path); double startTime = now(); mtcnn.detect(ncnn_img, finalBbox); double nDetectTime = calcElapsed(startTime, now()); printf("time: %d ms.\n ", (int)(nDetectTime * 1000)); int num_box = finalBbox.size(); printf("face num: %u \n", num_box); bool draw_face_feat = false; for (int i = 0; i < num_box; i++) { if (draw_face_feat) { const uint8_t red[3] = {255, 0, 0}; drawRectangle(inputImage, Width, Channels, finalBbox[i].x1, finalBbox[i].y1, finalBbox[i].x2, finalBbox[i].y2, red); const uint8_t blue[3] = {0, 0, 255}; for (int num = 0; num < 5; num++) { drawPoint(inputImage, Width, Channels, (int) (finalBbox[i].ppoint[num] + 0.5f), (int) (finalBbox[i].ppoint[num + 5] + 0.5f), blue); } } int left_eye_x = (int) (finalBbox[i].ppoint[0] + 0.5f); int left_eye_y = (int) (finalBbox[i].ppoint[5] + 0.5f); int right_eye_x = (int) (finalBbox[i].ppoint[1] + 0.5f); int right_eye_y = (int) (finalBbox[i].ppoint[6] + 0.5f); int dis_eye = (int) sqrtf((right_eye_x - left_eye_x) * (right_eye_x - left_eye_x) + (right_eye_y - left_eye_y) * (right_eye_y - left_eye_y)); int radius = MAX(1, dis_eye / 9); RemoveRedEyes(inputImage, inputImage, Width, Height, Channels, left_eye_x, left_eye_y, radius); RemoveRedEyes(inputImage, inputImage, Width, Height, Channels, right_eye_x, right_eye_y, radius); } saveImage("_done.jpg", Width, Height, Channels, inputImage); free(inputImage); printf("press any key to exit. \n"); getchar(); return 0; }
算法见 RemoveRedEyes ,这个技巧可以用于类似的图片颜色处理。
要看人脸检测的结果,把draw_face_feat 改为 true 即可。
项目地址:
https://github.com/cpuimage/MTCNN
参数也很简单,
mtcnn 模型文件路径 图片路径
例如: mtcnn ../models ../sample.jpg
用cmake即可进行编译示例代码,详情见CMakeLists.txt。
若有其他相关问题或者需求也可以邮件联系俺探讨。
邮箱地址是:
gaozhihan@vip.qq.com
原文:https://www.cnblogs.com/cpuimage/p/9000203.html