目录

测试图

读图

取像素值

保存图片

看下world-jpg.jpg属性

修改像素值

中间-1列

红色

绿色

蓝色

中间-1行

红色

绿色

蓝色

测试图

world.png

读图

#include <iostream>
#define STB_IMAGE_IMPLEMENTATION
#include "stb/stb_image.h"

using namespace std;

int main()
{
    int w,h,n;
    unsigned char *data = stbi_load("./world.png", &w, &h, &n, 0);
    cout << "宽: " << w << endl;
    cout << "高: " << h << endl;
    cout << "channel: " << n << endl;
}
宽: 1950
高: 1092
channel: 4

取像素值

#include <iostream>
#define STB_IMAGE_IMPLEMENTATION
#include "stb/stb_image.h"

using namespace std;

int main()
{
    int w,h,n;
    unsigned char *data = stbi_load("./world.png", &w, &h, &n, 0);
    cout << "宽: " << w << endl;
    cout << "高: " << h << endl;
    cout << "channel: " << n << endl;
    
    cout << "---------\n";
    int x=200,y=100;
    cout << data[y*w*n + x*n + 0] << endl;
    cout << data[y*w*n + x*n + 1] << endl;
    cout << data[y*w*n + x*n + 2] << endl;
    cout << "---------\n";
    cout << int(data[y*w*n + x*n + 0]) << endl;
    cout << int(data[y*w*n + x*n + 1]) << endl;
    cout << int(data[y*w*n + x*n + 2]) << endl;
}
宽: 1950
高: 1092
channel: 4
---------
0
A
%
---------
48
65
37

保存图片

#include <iostream>
#define STB_IMAGE_IMPLEMENTATION
#include "stb/stb_image.h"
#define STB_IMAGE_WRITE_IMPLEMENTATION
#include "stb/stb_image_write.h"
using namespace std;

int main()
{
    int w,h,n;
    unsigned char *data = stbi_load("./world.png", &w, &h, &n, 0);

    string name = "world-jpg.jpg"; 
    stbi_write_jpg(name.c_str(), w,h,n,data,95);
    string name2 = "world-png.png";
    stbi_write_png(name2.c_str(),w,h,n,data,0);
}
看下world-jpg.jpg属性
#include <iostream>
#define STB_IMAGE_IMPLEMENTATION
#include "stb/stb_image.h"

using namespace std;

int main()
{
    int w,h,n;
    unsigned char *data = stbi_load("./world-jpg.jpg", &w, &h, &n, 0);
    cout << "宽: " << w << endl;
    cout << "高: " << h << endl;
    cout << "channel: " << n << endl;
}
宽: 1950
高: 1092
channel: 3

修改像素值

中间-1列
红色
#include <iostream>
#define STB_IMAGE_IMPLEMENTATION
#include "stb/stb_image.h"
#define STB_IMAGE_WRITE_IMPLEMENTATION
#include "stb/stb_image_write.h"
using namespace std;

int main()
{
    int w,h,n;
    unsigned char *data = stbi_load("./world.png", &w, &h, &n, 0);

    int red_col = w/2;
    for(int i=0; i<h; i++)
    {
        data[w*i*n+red_col*n+0] = 255;
        data[w*i*n+red_col*n+1] = 0;
        data[w*i*n+red_col*n+2] = 0;
    }
    string name = "world-plot.jpg"; 
    stbi_write_jpg(name.c_str(), w,h,n,data,95);
    string name2 = "world-plot.png";
    stbi_write_png(name2.c_str(),w,h,n,data,0);
}

绿色
#include <iostream>
#define STB_IMAGE_IMPLEMENTATION
#include "stb/stb_image.h"
#define STB_IMAGE_WRITE_IMPLEMENTATION
#include "stb/stb_image_write.h"
using namespace std;

int main()
{
    int w,h,n;
    unsigned char *data = stbi_load("./world.png", &w, &h, &n, 0);

    int red_col = w/2;
    for(int i=0; i<h; i++)
    {
        data[w*i*n+red_col*n+0] = 0;
        data[w*i*n+red_col*n+1] = 255;
        data[w*i*n+red_col*n+2] = 0;
    }
    string name = "world-plot.jpg"; 
    stbi_write_jpg(name.c_str(), w,h,n,data,95);
    string name2 = "world-plot.png";
    stbi_write_png(name2.c_str(),w,h,n,data,0);
}

蓝色
#include <iostream>
#define STB_IMAGE_IMPLEMENTATION
#include "stb/stb_image.h"
#define STB_IMAGE_WRITE_IMPLEMENTATION
#include "stb/stb_image_write.h"
using namespace std;

int main()
{
    int w,h,n;
    unsigned char *data = stbi_load("./world.png", &w, &h, &n, 0);

    int red_col = w/2;
    for(int i=0; i<h; i++)
    {
        data[w*i*n+red_col*n+0] = 0;
        data[w*i*n+red_col*n+1] = 0;
        data[w*i*n+red_col*n+2] = 255;
    }
    string name = "world-plot.jpg"; 
    stbi_write_jpg(name.c_str(), w,h,n,data,95);
    string name2 = "world-plot.png";
    stbi_write_png(name2.c_str(),w,h,n,data,0);
}

中间-1行
红色
#include <iostream>
#define STB_IMAGE_IMPLEMENTATION
#include "stb/stb_image.h"
#define STB_IMAGE_WRITE_IMPLEMENTATION
#include "stb/stb_image_write.h"
using namespace std;

int main()
{
    int w,h,n;
    unsigned char *data = stbi_load("./world.png", &w, &h, &n, 0);

    int red_col = h/2;
    for(int i=0; i<w; i++)
    {
        data[w*red_col*n+i*n+0] = 255;
        data[w*red_col*n+i*n+1] = 0;
        data[w*red_col*n+i*n+2] = 0;
    }
    string name = "world-plot.jpg"; 
    stbi_write_jpg(name.c_str(), w,h,n,data,95);
    string name2 = "world-plot.png";
    stbi_write_png(name2.c_str(),w,h,n,data,0);
}

绿色
#include <iostream>
#define STB_IMAGE_IMPLEMENTATION
#include "stb/stb_image.h"
#define STB_IMAGE_WRITE_IMPLEMENTATION
#include "stb/stb_image_write.h"
using namespace std;

int main()
{
    int w,h,n;
    unsigned char *data = stbi_load("./world.png", &w, &h, &n, 0);

    int red_col = h/2;
    for(int i=0; i<w; i++)
    {
        data[w*red_col*n+i*n+0] = 0;
        data[w*red_col*n+i*n+1] = 255;
        data[w*red_col*n+i*n+2] = 0;
    }
    string name = "world-plot.jpg"; 
    stbi_write_jpg(name.c_str(), w,h,n,data,95);
    string name2 = "world-plot.png";
    stbi_write_png(name2.c_str(),w,h,n,data,0);
}

蓝色
#include <iostream>
#define STB_IMAGE_IMPLEMENTATION
#include "stb/stb_image.h"
#define STB_IMAGE_WRITE_IMPLEMENTATION
#include "stb/stb_image_write.h"
using namespace std;

int main()
{
    int w,h,n;
    unsigned char *data = stbi_load("./world.png", &w, &h, &n, 0);

    int red_col = h/2;
    for(int i=0; i<w; i++)
    {
        data[w*red_col*n+i*n+0] = 0;
        data[w*red_col*n+i*n+1] = 0;
        data[w*red_col*n+i*n+2] = 255;
    }
    string name = "world-plot.jpg"; 
    stbi_write_jpg(name.c_str(), w,h,n,data,95);
    string name2 = "world-plot.png";
    stbi_write_png(name2.c_str(),w,h,n,data,0);
}

# c++ # 图像处理
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