使用STB库在C++中操作JPG图片

使用STB库在C++中操作JPG图片

引用

CSDN

1.

https://blog.csdn.net/weixin_51133173/article/details/137955624

本文将介绍如何使用STB库在C++中操作JPG图片。通过具体的代码示例，我们将展示如何读取图片、获取像素值、保存图片以及修改像素值等基本操作。

测试图

s_l.jpg

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("./s_l.jpg", &w, &h, &n, 0);
    cout << "宽: " << w << endl;
    cout << "高: " << h << endl;
    cout << "channel: " << n << endl;
}  

宽: 400
高: 328
channel: 3  

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("./s_l.jpg", &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: 400
高: 328
channel: 3
---------
^
7
(
---------
94
55
40  

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("./s_l.jpg", &w, &h, &n, 0);
    string name = "s_l_new.jpg"; 
    stbi_write_jpg(name.c_str(), w,h,n,data,95);
}  

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("./s_l.jpg", &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 = "s_l_new.jpg"; 
    stbi_write_jpg(name.c_str(), w,h,n,data,95);
}  

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("./s_l.jpg", &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 = "s_l_new.jpg"; 
    stbi_write_jpg(name.c_str(), w,h,n,data,95);
}  

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("./s_l.jpg", &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 = "s_l_new.jpg"; 
    stbi_write_jpg(name.c_str(), w,h,n,data,95);
}  

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("./s_l.jpg", &w, &h, &n, 0);
    int red_row = h/2;
    for(int i=0; i<w; i++)
    {
        data[red_row*w*n+i*n+0] = 255;
        data[red_row*w*n+i*n+1] = 0;
        data[red_row*w*n+i*n+2] = 0;
    }
    string name = "s_l_new.jpg"; 
    stbi_write_jpg(name.c_str(), w,h,n,data,95);
}  

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("./s_l.jpg", &w, &h, &n, 0);
    int red_row = h/2;
    for(int i=0; i<w; i++)
    {
        data[red_row*w*n+i*n+0] = 0;
        data[red_row*w*n+i*n+1] = 255;
        data[red_row*w*n+i*n+2] = 0;
    }
    string name = "s_l_new.jpg"; 
    stbi_write_jpg(name.c_str(), w,h,n,data,95);
}  

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("./s_l.jpg", &w, &h, &n, 0);
    int red_row = h/2;
    for(int i=0; i<w; i++)
    {
        data[red_row*w*n+i*n+0] = 0;
        data[red_row*w*n+i*n+1] = 0;
        data[red_row*w*n+i*n+2] = 255;
    }
    string name = "s_l_new.jpg"; 
    stbi_write_jpg(name.c_str(), w,h,n,data,95);
}