解决CImg遇到的问题：无法处理jpg图像

问题描述

在学习CImg时，官方教程上有个例子写的非常详细，代码如下：

#include "CImg.h"
using namespace cimg_library;
int main() {
  CImg<unsigned char> image("lena.jpg"), visu(500,400,1,3,0);
  const unsigned char red[] = { 255,0,0 }, green[] = { 0,255,0 }, blue[] = { 0,0,255 };
  image.blur(2.5);
  CImgDisplay main_disp(image,"Click a point"), draw_disp(visu,"Intensity profile");
  while (!main_disp.is_closed() && !draw_disp.is_closed()) {
    main_disp.wait();
    if (main_disp.button() && main_disp.mouse_y()>=0) {
      const int y = main_disp.mouse_y();
      visu.fill(0).draw_graph(image.get_crop(0,y,0,0,image.width()-1,y,0,0),red,1,1,0,255,0);
      visu.draw_graph(image.get_crop(0,y,0,1,image.width()-1,y,0,1),green,1,1,0,255,0);
      visu.draw_graph(image.get_crop(0,y,0,2,image.width()-1,y,0,2),blue,1,1,0,255,0).display(draw_disp);
      }
    }
  return 0;
}

本想编译运行一下看看是怎么一回事，可是编译后运行时却出现下面的问题：

PS D:\linjiafengyang\Code\CV\CImg_latest\CImg-2.2.1_pre030218> g++ -o main1.exe .\Ex1.1.cpp -O2 -lgdi32
PS D:\linjiafengyang\Code\CV\CImg_latest\CImg-2.2.1_pre030218> ./main1
无效参数 - "C:\\WINDOWS\\Temp\\86ew44GS.pnm"
'gm.exe' 不是内部或外部命令，也不是可运行的程序
或批处理文件。
无效参数 - "C:\\WINDOWS\\Temp\\guOIMGi0.pnm"
'gm.exe' 不是内部或外部命令，也不是可运行的程序
或批处理文件。
无效参数 - "C:\\WINDOWS\\Temp\\66682Ky8.pnm"
'gm.exe' 不是内部或外部命令，也不是可运行的程序
或批处理文件。

[CImg] *** CImgIOException *** [instance(0,0,0,0,0000000000000000,non-shared)] CImg<unsigned char>::load(): Failed to recognize format of file 'lena.jpg'.
terminate called after throwing an instance of 'cimg_library::CImgIOException'
  what():  [instance(0,0,0,0,0000000000000000,non-shared)] CImg<unsigned char>::load(): Failed to recognize format of file 'lena.jpg'.

This application has requested the Runtime to terminate it in an unusual way.
Please contact the application's support team for more information.

解决办法

参考到这篇博客https://www.cnblogs.com/sheshouyanhun/p/3784837.html，安装ImageMagick，官网下载binary release版本https://www.imagemagick.org/script/install-source.php#windows，下载完安装即可。