对于计算机科学课，我应该编写一个程序，在这样的图片中找到未知数量的外星人的位置和大小：http://www-bcf.usc.edu/~stejada/csci101/Pix/MARS2.jpg。我目前有以下代码：
#include "Myro.h"
#include <iostream>
#include <stdlib.h>
#include <stdio.h>
#include "alien.h"
#include <vector>
using std::cout;
using std::cin;
using std::endl;
using std::vector;
void trackBlob(PicturePtr &aPic, int x, int y);
int BlobSize(PicturePtr &aPic, int x, int y, vector<int>& xLocs, vector<int>& yLocs);
vector<alien> found;
int returned;
int main()
{
returned = 0;
cout << "Pick a picture to search 0-5, or choose 6 to quit" << endl;
int selection;
cin >> selection;
PicturePtr thePic;
// Choose a picture to search
bool selecting = true;
while (selecting) {
switch (selection) {
case 0:
thePic = makePicture("MARS.jpg");
selecting = false;
break;
case 1:
thePic = makePicture("MARS1.jpg");
selecting = false;
break;
case 2:
thePic = makePicture("MARS2.jpg");
selecting = false;
break;
case 3:
thePic = makePicture("MARS3.jpg");
selecting = false;
break;
case 4:
thePic = makePicture("MARS4.jpg");
selecting = false;
break;
case 5:
thePic = makePicture("MARS6.jpg");
selecting = false;
break;
case 6:
cout << "Terminating." << endl;
return 0;
default:
cout << "Invalid input. Please try again." << endl << endl;
break;
}// end switch
} // end while
// Find the aliens
cout << endl;
cout << "Pic size: " << getHeight(thePic) * getWidth(thePic) << endl << endl;
int numGreen = 0;
for (int i = 0; i < getWidth(thePic); i++) {
for (int j = 0; j < getHeight(thePic); j++) {
Pixel pix;
pix = getPixel(thePic,i,j);
// Check for alien color
if (pix.R >= 100 && pix.R <= 120 && pix.G >= 240 && pix.G <= 255 && pix.B >= 1 && pix.B <= 15) {
trackBlob(thePic,i,j);
numGreen++;
}
else if (pix.R >= 165 && pix.R <= 185 && pix.G >= 215 && pix.G <= 235 && pix.B >= 65 && pix.B <= 85) {
trackBlob(thePic,i,j);
numGreen++;
}
else if (pix.R >= 130 && pix.R <= 155 && pix.G >= 210 && pix.G <= 230 && pix.B >= 145 && pix.B <= 175) {
trackBlob(thePic,i,j);
numGreen;
}
else if (pix.R >= 27 && pix.R <= 47 && pix.G <= 265 && pix.G >= 245 && pix.B >= 1 && pix.B <= 10) {
trackBlob(thePic,i,j);
numGreen++;
}
else if (pix.R >= 240 && pix.R <= 255 && pix.G <= 240 && pix.G >= 255 && pix.B >= 25 && pix.B <= 45) {
trackBlob(thePic,i,j);
numGreen++;
}
else if (pix.R >= 235 && pix.R <= 255 && pix.G <= 245 && pix.G >= 210 && pix.B >= 200 && pix.B <= 230) {
trackBlob(thePic,i,j);
numGreen++;
}
else if (pix.R <= 240 && pix.R >= 210 && pix.G <=255 && pix.G >= 240 && pix.B >= 1 && pix.B <= 10) {
trackBlob(thePic,i,j);
numGreen++;
}
}
}
cout << endl << endl;
cout << "Number of Aliens: " << found.size() << endl;
for (int n = 0; n < found.size(); n++) {
cout << "Position of Alien #" << n << ": (" << found[n].x << "," << found[n].y << ")" << endl;
cout << "Size of Alien #" << n << ": " << found[n].size << endl;
}
cout << endl << endl << "Number pixels tried: " << numGreen << endl << endl;
cout << "Times blob returned: " << returned << endl;
show(thePic);
return 0;
}
void trackBlob(PicturePtr &aPic, int x, int y) {
// Just to be safe
Pixel aPixel = getPixel(aPic,x,y);
//if (aPixel.R == 0 && aPixel.G == 0 && aPixel.B == 0)
//return;
// Find the size of the alien
vector<int> xLocs;
vector<int> yLocs;
int size = BlobSize(aPic,x,y,xLocs,yLocs);
cout << "Blob size: " << size << endl;
returned++;
// Make sure it's big enough to be an alien
if (size < 5) {
return;
}
alien newAlien;
// Find the position
newAlien.x = 0;
for (int i = 0; i < xLocs.size(); i++) {
newAlien.x += xLocs[i];
}
newAlien.x = newAlien.x/xLocs.size();
newAlien.y = 0;
for (int j = 0; j < yLocs.size(); j++) {
newAlien.y += yLocs[j];
}
newAlien.y = newAlien.y/yLocs.size();
found.push_back(newAlien);
}
int BlobSize(PicturePtr &aPic, int x, int y, vector<int>& xLocs, vector<int>& yLocs)
{
if (x >= getWidth(aPic) || x < 0)
return 0;
Pixel pix = getPixel(aPic,x,y);
// Just to be safe
//if (pix.R == 0 && pix.G == 0 && pix.B == 0)
//return 0;
bool isAlien = false;
if (pix.R >= 100 && pix.R <= 120 && pix.G >= 240 && pix.G <= 255 && pix.B >= 1 && pix.B <= 15)
isAlien = true;
else if (pix.R >= 165 && pix.R <= 185 && pix.G >= 215 && pix.G <= 235 && pix.B >= 65 && pix.B <= 85)
isAlien = true;
else if (pix.R >= 130 && pix.R <= 155 && pix.G >= 210 && pix.G <= 230 && pix.B >= 145 && pix.B <= 175)
isAlien = true;
else if (pix.R >= 27 && pix.R <= 47 && pix.G <= 265 && pix.G >= 245 && pix.B >= 1 && pix.B <= 10)
isAlien = true;
else if (pix.R >= 240 && pix.R <= 255 && pix.G <= 240 && pix.G >= 255 && pix.B >= 25 && pix.B <= 45)
isAlien = true;
else if (pix.R >= 235 && pix.R <= 255 && pix.G <= 245 && pix.G >= 210 && pix.B >= 200 && pix.B <= 230)
isAlien = true;
else if (pix.R <= 240 && pix.R >= 210 && pix.G <=255 && pix.G >= 240 && pix.B >= 1 && pix.B <= 10)
isAlien = true;
if (!isAlien)
return 0;
// Store the location in the position vectors
xLocs.push_back(x);
yLocs.push_back(y);
// Make sure the pixel doesn't get counted again
setPixelColor(aPic,x,y,0,0,0);
int size = 0;
for (int i = 0; i <= 2; i++) {
for (int j = 0; j <= 2; j++) {
if (i == 0 && j == 0) {
break;
}
size += BlobSize(aPic,x + (i-1), y + (j-1),xLocs,yLocs);
}
}
return 1 + size;
}
当我运行代码时，它说它发现了几百个“外星人”。如果有帮助，它找到的每个都比最后一个大。我已经盯着这几天了，不知道出了什么问题。任何帮助将不胜感激。
谢谢！
答案 0 :(得分：4)
首先，您应该删除BlobSize（）中的注释，如下所示：
// So pixels aren't counted twice
if (pix.R == 0 && pix.G == 0 && pix.B == 0)
return 0;
由于BlobSize（）将计算的像素更改为黑色，因此您需要在代码中保留这些行，这样就不会将像素计算两次。
另外，BlobSize（）末尾的for循环有点错误。它应该是这样的：
for (int i = -1; i <= 1; i++) {
for (int j = -1; j <= 1; j++) {
// skip pixel at this location
if (i == 0 && j == 0) {
continue;
}
size += BlobSize(aPic,x + (i-1), y + (j-1),xLocs,yLocs);
}
}
之前的方式是检查当前位置的像素上方和左侧的像素，查看i == 0 && j == 0，然后跳过检查第一列。该程序将在其他6个像素（包括当前位置的像素）上运行BlobSize（）。
顺便说一下，很好地使用了向量和递归。对不起，如果我回答得太晚了，你已经把它打开了。因为延期，我周日开始进入。