图像处理——BGR2HSV

将BGR彩色转换为HSV彩色图像。

python代码：

import cv2import numpy as npdef BGR2HSV(_img):img = _img / 255.0hsv_img = np.zeros_like(img, dtype=np.float32)# get max and minmax_v = np.max(img, axis=2).copy()min_v = np.min(img, axis=2).copy()min_arg = np.argmin(img, axis=2) # 最小值在数组中占的位置# Hhsv_img[..., 0][np.where(max_v == min_v)] = 0## min = Bind = np.where(min_arg == 0)hsv_img[..., 0][ind] = 60 * (img[..., 1][ind] - img[..., 2][ind]) / (max_v[ind] - min_v[ind]) + 60## min = Rind = np.where(min_arg == 2)hsv_img[..., 0][ind] = 60 * (img[..., 0][ind] - img[..., 1][ind]) / (max_v[ind] - min_v[ind]) + 120## min = Gind = np.where(min_arg == 1)hsv_img[..., 0][ind] = 60 * (img[..., 2][ind] - img[..., 0][ind]) / (max_v[ind] - min_v[ind]) + 300# Shsv_img[..., 1] = max_v.copy() - min_v.copy()# Vhsv_img[..., 2] = max_v.copy()return hsv_imgdef BGR2HSV_v2(img):img = img / 255.0img_hsv = np.zeros([H, W, C])for i in range(H):for j in range(W):max = np.max(img[i, j, :])min = np.min(img[i, j, :])if min == max:img_hsv[i, j, 0] = 0elif min == img[i, j, 0]: # min = Bimg_hsv[i, j, 0] = 60 * (img[i, j, 1] - img[i, j, 2]) / (max - min) + 60elif min == img[i, j, 2]: # min = Rimg_hsv[i, j, 0] = 60 * (img[i, j, 0] - img[i, j, 1]) / (max - min) + 180elif min == img[i, j, 1]:img_hsv[i, j, 0] = 60 * (img[i, j, 2] - img[i, j, 0]) / (max - min) + 300img_hsv[i, j, 1] = max - minimg_hsv[i, j, 2] = maxreturn img_hsvdef HSV2RGB(_img, hsv):''':param _img: GBR图:param hsv: hsv图:return:'''img = _img / 255.max_v = np.max(img, axis=2).copy()min_v = np.min(img, axis=2).copy()img_rgb = np.zeros_like(img)H = hsv[..., 0]S = hsv[..., 1]V = hsv[..., 2]C = SH_temp = H/60.X = C * (1 - np.abs(H_temp % 2 - 1))Z = np.zeros_like(H)vals = [[Z, X, C],[Z, C, X],[X, C, Z],[C, X, Z],[C, Z, X],[X, Z, C]]for i in range(6):ind = np.where((i <= H_temp) & (H_temp<(i+1)))img_rgb[..., 0][ind] = (V - C)[ind] + vals[i][0][ind]img_rgb[..., 1][ind] = (V - C)[ind] + vals[i][1][ind]img_rgb[..., 2][ind] = (V - C)[ind] + vals[i][2][ind]img_rgb[np.where(max_v == min_v)] = 0img_rgb = np.clip(img_rgb, 0, 1)img_rgb = (img_rgb * 255).astype(np.uint8)return img_rgbimg = cv2.imread("../imori.jpg")hsv = BGR2HSV(img)hsv[..., 0] = (hsv[..., 0] + 180) % 360 # 反相rgb = HSV2RGB(img, hsv)cv2.imshow("result", rgb)cv2.waitKey(0)cv2.destroyAllWindows()

C++代码：

#include <opencv2/core.hpp>#include <opencv2/highgui.hpp>#include <iostream>//BGR->HSVcv::Mat BGR2HSV(cv::Mat img) {int height = img.rows;int width = img.cols;float r, g, b;float h, s, v;float _max, _min;cv::Mat hsv = cv::Mat::zeros(height, width, CV_32FC3);for (int y = 0; y < height; y++) {for (int x = 0; x < width; x++) {r = (float)img.at<cv::Vec3b>(y, x)[2] / 255;g = (float)img.at<cv::Vec3b>(y, x)[1] / 255;b = (float)img.at<cv::Vec3b>(y, x)[0] / 255;_max = fmax(r, fmax(g, b));_min = fmin(r, fmin(g, b));// Hif (_min == _max){h = 0;}else if (_min == b) {h = 60 * (g - r) / (_max - _min) + 60;}else if (_min == r) {h = 60 * (b - g) / (_max - _min) + 180;}else if (_min == g) {h = 60 * (r - b) / (_max - _min) + 300;}// Vv = _max;// Ss = _max - _min;hsv.at<cv::Vec3f>(y, x)[0] = h;hsv.at<cv::Vec3f>(y, x)[1] = s;hsv.at<cv::Vec3f>(y, x)[2] = v;}}return hsv;}cv::Mat HSV2BGR(cv::Mat hsv) {int height = hsv.rows;int width = hsv.cols;float h, s, v;double c, h_, x_;double r, g, b;cv::Mat out = cv::Mat::zeros(height, width, CV_8UC3);for (int y = 0; y < height; y++){for (int x = 0; x < width; x++) {h = hsv.at<cv::Vec3f>(y, x)[0];s = hsv.at<cv::Vec3f>(y, x)[1];v = hsv.at<cv::Vec3f>(y, x)[2];c = s;h_ = h / 60;x_ = c * (1 - abs(fmod(h_, 2) - 1));r = g = b = v - c;if (h_ < 1) {r += c;g += x_;}else if (h_ < 2) {r += x_;g += c;}else if (h_ < 3) {g += c;b += x_;}else if (h_ < 4) {g += x_;b += c;}else if (h_ < 5) {r += x_;b += c;}else if (h_ < 6){r += c;b += x_;}out.at<cv::Vec3b>(y, x)[0] = (uchar)(b * 255);out.at<cv::Vec3b>(y, x)[1] = (uchar)(g * 255);out.at<cv::Vec3b>(y, x)[2] = (uchar)(r * 255);}}return out;}cv::Mat inverse_hue(cv::Mat hsv) {int height = hsv.rows;int width = hsv.cols;for (int y = 0; y < height; y++) {for (int x = 0; x < width; x++) {hsv.at<cv::Vec3f>(y, x)[0] = fmod((hsv.at<cv::Vec3f>(y, x)[0] + 180), 360);}}return hsv;}int main(int argc, const char* argv[]) {cv::Mat img = cv::imread("./imori.jpg", cv::IMREAD_COLOR);cv::Mat hsv = BGR2HSV(img);cv::Mat inverse_hsv = inverse_hue(hsv);cv::Mat out = HSV2BGR(inverse_hsv);cv::imshow("sample", out);cv::waitKey(0);cv::destroyAllWindows();return 0;}