關於印象筆記的掃描寶——簡單的影象背景去除(去底色)演算法小結
阿新 • • 發佈:2019-01-31
前段時間研究了下印象筆記的掃描寶,發現它將手機拍下的照片都能處理成白板背景,而且處理的很乾淨,出於好奇並學習,自己琢磨出了個簡易的去底色演算法,雖然不能跟印象筆記的相比,但是效果也還闊以,供自己學習了,有興趣的朋友歡迎指教。
文中測試圖分別如下:
圖1
圖2
圖3
圖4
法一:伽馬變換
主要思想:調整色階,明暗影象求加;
void ls::gamma2Add(cv::Mat &src,cv::Mat &dst) { Mat image; resize(src, image, Size(((float)src.cols/(float)src.rows)*krows,krows)); Scan scan; cv::Mat dst1,dst2; scan.gammaCorrection(image, dst1, 0.45); scan.gammaCorrection(image, dst2, 2); dst = dst1 + dst2; }
效果如下:
法二:替換背景的畫素值;
主要思想,首先遍歷影象(遍歷可以優化),統計出影象中最多的顏色畫素,然後替換成255;
void changeRGB(Mat &src) { // Mat image; // detailEnhance(src, src); Mat gray; cvtColor(src, gray, CV_BGR2GRAY); MatND hist = getHistogram(gray); double maxVal = 0,minVal = 0; //獲取最大值和最小值 int hpt = static_cast<int>(0.9 * histSize[0]); minMaxLoc(hist, &minVal, &maxVal,0,0); cout<<minVal<<","<<maxVal<<endl; vector<int> kChange; // int th = me / maxVal; // int nonzero = countNonZero(gray); // double ratio = nonzero / (double)(gray.cols * gray.rows); // cout<<ratio<<endl; for (int i = 0; i < histSize[0]; i ++) { float binVal = hist.at<float>(i); //cout<<binVal<<endl; int intensity = static_cast<int>(binVal*hpt/maxVal); if (abs(intensity - 255) < 60) { intensity = 255; hist.at<float>(i) = intensity * maxVal/hpt; } // if (abs(intensity - 0) > 30) { // intensity = 0; // hist.at<float>(i) = intensity * maxVal/hpt; // } // } minMaxLoc(hist,&minVal, &maxVal,0,0); cout<<minVal<<","<<maxVal<<endl; for (int num = 0; num < histSize[0]; num ++) { if (hist.at<float>(num) >= 0.5*maxVal)//( hist.at<float>(i) >= ratio*maxVal && hist.at<float>(i) <= 1.0*maxVal)//3.63 { kChange.push_back(num); } } int nl = src.rows; int nc = src.cols; // if (src.isContinuous()) { // nc = nc * nl; // nl = 1; // } for (int j = 0; j < nl; j ++) { // uchar *data = src.ptr<uchar>(j); for (int l = 0; l < nc; l ++) { int b = 0.11 * src.at<Vec3b>(j, l)[0]; int g = 0.59 * src.at<Vec3b>(j, l)[1]; int r = 0.30 * src.at<Vec3b>(j, l)[2]; int greyVal = b + g + r; for (int ii = 0; ii < kChange.size(); ii ++) { if (abs(greyVal - kChange[ii]) <= 18)// // if (greyVal == kChange[ii]) { src.at<Vec3b>(j, l)[0] = 255; src.at<Vec3b>(j, l)[1] = 255; src.at<Vec3b>(j, l)[2] = 255; } } } } }
效果如下:
不難發現還是有一些瑕疵在的,希望能與大家交流討論。。