C++ 图像处理库【CImg】配置以及简单使用
1. CImg的配置
- 下载CImg的包到指定的文件夹下，解压
- 然后只需要在编写的cpp或hpp文件中加入
#include "XX/CImg.h" // XX/是指CImg所在的路径
using namespace cimg_library;
- 编译命令（环境为windows下的MinGW）
g++ -o HelloWorld.exe HelloWorld.cpp -O2 -lgdi32
2.简单使用
1. 读入1.bmp 文件
CImg<unsigned char> SrcImg;
SrcImg.load_bmp("1.bmp");
2. 用CImg.display() 显示
void test_display(CImg<unsigned char> SrcImg) {
SrcImg.display("work1");
}
3. 把1.bmp文件的白色区域变成红色，黑色区域变成绿色
void test_change(CImg<unsigned char> SrcImg) {
CImg<unsigned char> Img = SrcImg;
cimg_forXY(Img, x, y) {
if (Img(x,y,0) == 255 && Img(x,y,1) == 255 && Img(x,y,2) == 255) {
Img(x,y,0) = 255;
Img(x,y,1) = 0;
Img(x,y,2) = 0;
}
}
cimg_forXY(Img, x, y) {
if (Img(x,y,0) == 0 && Img(x,y,1) == 0 && Img(x,y,2) == 0) {
Img(x,y,0) = 0;
Img(x,y,1) = 255;
Img(x,y,2) = 0;
}
}
Img.display("work2");
}
4. 在图上绘制一个圆形区域，圆心坐标(50,50)，半径为30，填充颜色为蓝色
- 未使用CImg的接口函数
void DrawCircle_blue1(CImg <unsigned char> TempImg) {
CImg<unsigned char> SrcImg = TempImg;
cimg_forXY(SrcImg, x, y) {
if (pow(pow(x-50,2)+pow(y-50,2),0.5) < 30) {
SrcImg(x,y,0) = 0;
SrcImg(x,y,1) = 0;
SrcImg(x,y,2) = 255;
}
}
SrcImg.display("work3.1");
}
- 使用接口函数draw_circle()
void DrawCircle_blue2(CImg <unsigned char> TempImg) {
unsigned char blue[] = {0,0,255};
TempImg.draw_circle(50, 50, 30, blue);
TempImg.display("work3.2");
}
PS: 这个感觉自己实现的算法和接口函数实现的效果差不多
5. 在图上绘制一个圆形区域，圆心坐标(50,50)，半径为3，填充颜色为黄色
- 未使用CImg的接口函数
void DrawCircle_yellow1(CImg <unsigned char> TempImg) {
CImg<unsigned char> SrcImg = TempImg;
cimg_forXY(SrcImg, x, y) {
if (pow(pow(x-50,2)+pow(y-50,2),0.5) < 3) {
SrcImg(x,y,0) = 200;
SrcImg(x,y,1) = 155;
SrcImg(x,y,2) = 0;
}
}
SrcImg.display("work4.1");
}
- 使用接口函数draw_circle()
void DrawCircle_yellow2(CImg <unsigned char> TempImg) {
unsigned char yellow[] = {200, 155, 0};
TempImg.draw_circle(50, 50, 3, yellow);
TempImg.display("work4.2");
}
PS: 这个虽然接口函数的效果也并不是特别好，但是明显比我的要好很多，但是因为遍历图片的像素点是对图片进行采样所以点坐标为整数值，圆的半径越小意味着我们取的像素点范围越少，点越少，所以图片的效果会较差，甚至接近正方形，可能接口的函数有更好的实现方法，尝试去翻了翻源码没太看懂
6. 在图上绘制一条长为100的直线段，起点坐标为(0, 0)，方向角为35度，直线的颜色为蓝色
- 未使用CImg的接口函数
void DrawLine1(CImg <unsigned char> TempImg) {
CImg<unsigned char> SrcImg = TempImg;
double x0 = 100*cos(35*pi/180);
double y0 = 100*sin(35*pi/180);
cimg_forXY(SrcImg, x, y) {
if (x == 0) {
if (y == 0) {
SrcImg(x,y,0) = 0;
SrcImg(x,y,1) = 0;
SrcImg(x,y,2) = 255;
}
}
else {
if (cmp((double)y, (double)x*tan(35*pi/180)) && (double)x <= x0 && (double)y <= y0) {
SrcImg(x,y,0) = 0;
SrcImg(x,y,1) = 0;
SrcImg(x,y,2) = 255;
}
}
}
SrcImg.display("work5.1");
}
//用于上面函数的一个辅助函数，来判断相等条件
bool cmp(double x , double y) { //compare x and y，如果差值小于一定范围则近似相等
if (abs(x - y) <= 0.5)
return 1;
return 0;
}
- 使用接口函数draw_line()
void DrawLine2(CImg <unsigned char> TempImg) {
unsigned char blue[] = {0,0,255};
TempImg.draw_line(0,0,100*cos(35*pi/180),100*sin(35*pi/180),blue);
TempImg.display("work5.2");
}
PS: 这个比较效果感觉肉眼很难看出差距，但是因为遍历图片的像素点是对图片进行采样所以点坐标为整数值，所以不可能存在彻底等于所得的浮点数tan角要求的坐标，只能通过设置误差尽可能小，也就是直线的粗细，通过设置cmp函数调节几个值（0.1, 0.3, 0.5, 1.0）发现0.5的效果是最好的。
7. 把上面的操作结果保存为 2.bmp
SrcImg.save("2.bmp");
3. 将上述实现的函数封装为c++的一个类
ex.hpp:
#ifndef _EX_HPP_
#define _EX_HPP_
#include "../CImg.h"
#include ex.cpp
#include "ex.hpp"
using namespace std;
bool cmp(double x , double y);
Test::Test() {
//name = "work1";
SrcImg.load_bmp("1.bmp");
}
Test::~Test() {}
void Test::Todisplay() {
//string t = name;
SrcImg.display("homework");
}
CImg<unsigned char> Test::getSrcImg() {
return SrcImg;
}
void Test::change() {
//name = "work2";
//CImg Img = SrcImg;
cimg_forXY(SrcImg, x, y) {
if (SrcImg(x,y,0) == 255 && SrcImg(x,y,1) == 255 && SrcImg(x,y,2) == 255) {
SrcImg(x,y,0) = 255;
SrcImg(x,y,1) = 0;
SrcImg(x,y,2) = 0;
}
}
cimg_forXY(SrcImg, x, y) {
if (SrcImg(x,y,0) == 0 && SrcImg(x,y,1) == 0 && SrcImg(x,y,2) == 0) {
SrcImg(x,y,0) = 0;
SrcImg(x,y,1) = 255;
SrcImg(x,y,2) = 0;
}
}
}
void Test::DrawCircle_blue1() {
cimg_forXY(SrcImg, x, y) {
if (pow(pow(x-50,2)+pow(y-50,2),0.5) < 30) {
SrcImg(x,y,0) = 0;
SrcImg(x,y,1) = 0;
SrcImg(x,y,2) = 255;
}
}
}
void Test::DrawCircle_yellow1() {
cimg_forXY(SrcImg, x, y) {
if (pow(pow(x-50,2)+pow(y-50,2),0.5) < 3) {
SrcImg(x,y,0) = 200;
SrcImg(x,y,1) = 155;
SrcImg(x,y,2) = 0;
}
}
}
void Test::DrawLine1() {
double x0 = 100*cos(35*pi/180);
double y0 = 100*sin(35*pi/180);
cimg_forXY(SrcImg, x, y) {
if (x == 0) {
if (y == 0) {
SrcImg(x,y,0) = 0;
SrcImg(x,y,1) = 0;
SrcImg(x,y,2) = 255;
}
}
else {
if (cmp((double)y, (double)x*tan(35*pi/180)) && (double)x <= x0 && (double)y <= y0) {
SrcImg(x,y,0) = 0;
SrcImg(x,y,1) = 0;
SrcImg(x,y,2) = 255;
}
}
}
}
void Test::DrawCircle_blue2() {
unsigned char blue[] = {0,0,255};
SrcImg.draw_circle(50, 50, 30, blue);
}
void Test::DrawCircle_yellow2() {
unsigned char yellow[] = {200, 155, 0};
SrcImg.draw_circle(50, 50, 3, yellow);
}
void Test::DrawLine2() {
unsigned char blue[] = {0,0,255};
SrcImg.draw_line(0,0,100*cos(35*pi/180),100*sin(35*pi/180),blue);
}
bool cmp(double x , double y) { //compare x and y，如果差值小于一定范围则近似相等
if (abs(x - y) <= 0.5)
return 1;
return 0;
}
main.cpp
#include "ex.hpp"
using namespace std;
int main(int argc, char const *argv[])
{
Test pic;
Test pic1;
pic.change();
pic.DrawCircle_blue1();
pic.DrawCircle_yellow1();
pic.DrawLine1();
pic.Todisplay();
CImg<unsigned char> temp = pic.getSrcImg();
temp.save("2.bmp");
pic1.change();
pic1.DrawCircle_blue2();
pic1.DrawCircle_yellow2();
pic1.DrawLine2();
pic1.Todisplay();
CImg<unsigned char> temp1 = pic1.getSrcImg();
temp1.save("2.1.bmp");
return 0;
}
运行并存储后实现的整体效果图如下所示：
(1) 未使用接口函数：
(2) 使用接口函数：
完整代码参见：
https://github.com/WangPerryWPY/Computer-Version/tree/master/EX1