OpenCV - 使用calcHist的混乱

问题描述

我已经阅读calcHist（）的文档很多次，但我认为我对OpenCV和生锈的编程技能的不熟练完全排除了我的理解。

I've read the documentation for calcHist() many times, but I think my inexperience with OpenCV and rusty programming skills are completely precluding me from understanding it.

我想要计算HSV图像（色相或通道[0]）的一个通道中的像素，以便使用10个接近颜色的区段（让我们使用这个例子，我偷了网络范围 - fwiw，似乎错过省略紫红色）：

I'm looking to count pixels in one channel of an HSV image (Hue, or channel[0]) for segmentation purposes using 10 bins that closely approximate color according to something like (let's use this as an example, I stole the ranges off the web - fwiw, it seems erroneous to omit purple-red):

红色：0-19 & 330-360
红黄色（RY）：20-49
黄色：50-69
YG：70-84
绿色：85-170
GB： 171-191
蓝色：192-264
BP：265-289
紫色：290-329

Red: 0-19 & 330-360Red-Yellow (RY): 20-49Yellow: 50-69YG: 70-84Green: 85-170GB: 171-191Blue: 192-264BP: 265-289Purple: 290-329

。

那么如何用calcHist做呢？

So how do I do this with calcHist?

>

I'm as far as:

#include <opencv2/opencv.hpp>
#include <vector>
#include <opencv2/highgui/highgui.hpp>
#include <iostream>

using namespace std;
using namespace cv;

int main(int argc, char *argv[])
{
    Mat scene, sceneHSV, dest, histo;
    int numImages = 1, histChannel[] = {0}, dims = 1, histSize[] = {10};

    float redRange[] = {0, 10};
    float roRange[] = {10, 25};
    float orangeRange[] = {25, 35};
    float oyRange[] = {35, 42};
    float yellowRange[] = {42, 85};
    float ygRange[] = {85, 96};
    float greenRange[] = {96, 132};
    float gbRange[] = {132, 145};
    float blueRange[] = {145, 160};
    float bpRange[] = {160, 165};
    float purpleRange[] = {165, 180};

    const float* ranges[] = {redRange, roRange, orangeRange, oyRange, yellowRange, ygRange, greenRange, gbRange, blueRange, bpRange, purpleRange};

    vector<Mat> channels;

    scene = imread("Apple.jpg", 1);
    if (scene.data == NULL)
    {
        cout<<"FAIL"<<endl;
        cin.get();
    }

    cvtColor(scene, sceneHSV, CV_BGR2HSV);
    dilate(sceneHSV, sceneHSV, Mat(), Point(-1, -1), 1, BORDER_CONSTANT, 1);
    pyrMeanShiftFiltering(sceneHSV, dest, 2, 50, 3);
    split(sceneHSV, channels);

    calcHist(&scene, 1, histChannel, Mat(), histo, dims, histSize, ranges, false, false);

    cout<<histo<<endl;

    waitKey(0);

    return 0;
}

现在什么？在这种情况下，calcHist的参数是什么样子的，输出直方图是什么样子的？只是一个充满int的1x9数组？

Now what? What would the arguments to calcHist look like in this case, and what does the output histogram look like? Simply a 1x9 array full of ints?

非常感谢。

推荐答案

我修改了

您还可以查看文档of cvtColor

You might also want to take a look at the documentation of cvtColor here

请注意，我没有尝试编译或运行此代码，所以我不保证它会工作。但是，它可能是有用的参考。

Note that I have not tried to compile or run this code so I do not guarantee that it will work. But nonetheless, it might be useful as a reference.

Mat hist;
int nimages = 1; // Only 1 image, that is the Mat scene.
int channels[] = {0} // Index for hue channel
int dims = 1 // Only 1 channel, the hue channel
int histSize[] = {9} // 9 bins, 1 each for Red, RY, Yellow, YG etc.
float hranges[] = { 0, 180 }; // hue varies from 0 to 179, see cvtColor
const float *ranges[] = {hranges};

// Compute the histogram.
calcHist(&scene,
nimages,
channels,
Mat(), // No mask
hist, dims, histSize, ranges, uniform=true)

// Now hist will contain the counts in each bin.
// Lets just print out the values. Note that you can output Mat using std::cout
cout << "Histogram: " << endl << hist << endl;

// To access the individual bins, you can either iterate over them
// or use hist.at<uchar>(i, j); Note that one of the index should be 0
// because hist is 1D histogram. Print out hist.rows and hist.cols to see if hist is a N x 1 or 1 x N matrix.
/*
MatIterator_<uchar> it, end;
int binIndex = 0;
for( it = hist.begin<uchar>(), end = hist.end<uchar>(); it != end; ++it)
{
  printf("Count in %d bin: %d\n", binIndex, *it);
  ++binIndex;
}
*/

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