【发布时间】：2019-11-20 20:13:34
【问题描述】：
我正在尝试使用 c++ 和 opencv 编写一个代码，该代码将识别哪个蓝色像素从左、右、上和下首先出现。 我正在使用的图片是这张：
而我想收到的是这样的图片：
到目前为止，这是我的代码，我真的不明白为什么它不起作用。
void findBluePixels(Mat& original, Point2f min_x, Point2f max_x, Point2f min_y, Point2f max_y) {
//First I set every point to the beginning of the image
min_x = Point(0, 0);
max_x = Point(0, 0);
min_y = Point(0, 0);
max_y = Point(0, 0);
//looking for the most left blue pixel (the blue pixel with the smallest x value)
//we are going through every column and every row
for (int col = 0; col < original.cols; col++) {
for (int row = 0; row < original.rows; row++) {
//we check for every pixel if the pixel is blue and if the column of the pixel is bigger or equal to the beginning of the image
if (original.at<Vec3b>(row, col)[0] == 255 &&
original.at<Vec3b>(row, col)[1] == 0 &&
original.at<Vec3b>(row, col)[2] == 0 && col >= min_x.y) {
//if yes we have new value for the min_x and we stop looking because we have found the most left blue pixel
min_x = Point(row, col);
break;
}
}
}
//looking for the most right blue pixel (the blue pixel with the biggest x value)
//we are going through every column and every row
for (int col = 0; col < original.cols; col++) {
for (int row = 0; row < original.rows; row++) {
//we check for every pixel if the pixel is blue and if the column of the pixel is bigger or equal to the beginning of the image
if (original.at<Vec3b>(row, col)[0] == 255 &&
original.at<Vec3b>(row, col)[1] == 0 &&
original.at<Vec3b>(row, col)[2] == 0 && col >= max_x.y) {
//if yes we have new value for the max_x, but we don't break because we are looking for the biggest blue pixel
//we continue to search until the end of the picture
max_x = Point(row, col);
}
}
}
//looking for the highest blue pixel (the blue pixel with the smallest y value)
//we are going through every row and every column
for (int row = 0; row < original.rows; row++) {
for (int col = 0; col < original.cols; col++) {
//we check for every pixel if the pixel is blue and if the row of the pixel is bigger or equal to the beginning of the image
if (original.at<Vec3b>(row, col)[0] == 255 &&
original.at<Vec3b>(row, col)[1] == 0 &&
original.at<Vec3b>(row, col)[2] == 0 && row >= min_y.x) {
//if yes we have new value for the min_y and we stop looking because we have found the highest blue pixel
min_y = Point(row, col);
break;
}
}
}
//looking for the most down blue pixel (the blue pixel with the biggest y value)
//we are going through every column and every row
for (int row = 0; row < original.rows; row++) {
for (int col = 0; col < original.cols; col++) {
//we check for every pixel if the pixel is blue and if the row of the pixel is bigger or equal to the beginning of the image
if (original.at<Vec3b>(row, col)[0] == 255 &&
original.at<Vec3b>(row, col)[1] == 0 &&
original.at<Vec3b>(row, col)[2] == 0 && row >= max_y.x) {
//if yes we have new value for the max_y, but we don't break because we are looking for the biggest blue pixel
//we continue to search until the end of the picture
max_y = Point(row, col);
}
}
}
//Here I want to make green points on the pixels we have found
circle(original, min_x, 3, Scalar(0, 255, 0), 8, LINE_AA);
circle(original, max_x, 3, Scalar(0, 255, 0), 8, LINE_AA);
circle(original, min_y, 3, Scalar(0, 255, 0), 8, LINE_AA);
circle(original, max_y, 3, Scalar(0, 255, 0), 8, LINE_AA);
}
我最后收到的点是完全随机的。
如果有人可以提供帮助，我将不胜感激！ :)
【问题讨论】：
-
不知道，但你应该提取一个函数
bool is_blue( const Pixel &)以使代码更易读和简洁。 -
对不起，但你的逻辑对我来说似乎完全随机。无论如何，这就是调试器的用途，使用它来准确地找出您的程序何时何地偏离了您的期望。
-
您没有在帖子中指定您的坐标系，这很难确定。但是
col >= max_x.y将我认为是 x 坐标的列与 y 坐标进行比较。那是没有意义的。所有其他比较都存在同样的问题，您似乎混淆了 x 和 y。 -
你的符号有问题。如果 x 从左到右，y 从上到下（或相反，w/e），
col对应于你的 x 值和row到 y 值。如果这不是您想要的符号，那么最左边和最右边的定义是错误的。 -
min_x和max_x的代码相同。在某处搞砸了>=和<=。