While I was working on a project, I noticed that I am not able to load images. Here is the simple code that I used to check:
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/objdetect/objdetect.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <iostream>
using namespace cv;
using namespace std;
int main( int argc, char** argv )
{
if( argc != 2)
{
cout <<" Usage: display_image ImageToLoadAndDisplay" << endl;
return -1;
}
Mat image;
image = imread(argv[1], CV_LOAD_IMAGE_COLOR); // Read the file
if(! image.data ) // Check for invalid input
{
cout << "Could not open or find the image" << std::endl ;
return -1;
}
Mat gray_image;
cv::cvtColor(image, gray_image, CV_RGB2GRAY);
imwrite("Gray_Image.jpg",gray_image);
return 0;
}
Here is its output when I execute it:
root#beaglebone:~# ./tryit lena.jpg
Could not open or find the image
I tried to directly use the address of the image ("/home/root/lena.jpg") instead of argv[1] but nothing changed.
What can be the problem?
ps: I am cross-compiling this OpenCV program and then running it on my BeagleBone which has Angstrom Linux installed on it. Can this problem related to it?
I solved my problem by deleting existing OpenCV libraries on my angstrom image and replacing them with the working ones.
Try saving the image with a png extension and then opening it. For some reason, files with a png extension work better than other extensions like jpg/gif.
Related
Newbie here. I'm trying to learn Xcode and I've written a simple code here that takes a string input from an Input file and is meant to print it out to an Output file. Easy stuff, if it wasn't that I cannot figure out why Xcode isn't letting be edit Input and Output files from within the app. Here's the code:
#include <iostream>
#include <string>
#include <fstream>
using namespace std;
int main()
{
ifstream Input;
ofstream Output;
Input.open("Input.txt");
if(!Input)
{
cout << "Input file not found" << endl;
return 1;
}
Output.open("Output.txt");
if(!Output)
{
cout << "Output file not found" << endl;
return 3;
}
string prova;
Input >> prova;
Output << prova;
return 0;
}
To make absolutely clear what I mean the editor doesn't let me edit Input files, I've uploaded a video here, hope it helps. Thank you.
Specs: Xcode Version 11.4 -> can't update it to the last version because my Mac is too old / Mac OS Catilina Version 10.15.7
I've been trying to run OpenCV using CLion IDE under Windows. When I try to run this sample code for loading and displaying an image
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <iostream>
using namespace cv;
using namespace std;
int main( int argc, char** argv )
{
if( argc != 2)
{
cout <<" Usage: display_image ImageToLoadAndDisplay" << endl;
return -1;
}
Mat image;
image = imread("earth.jpg", CV_LOAD_IMAGE_COLOR); // Read the file
if(! image.data ) // Check for invalid input
{
cout << "Could not open or find the image" << std::endl ;
return -1;
}
namedWindow( "Display window", WINDOW_AUTOSIZE );// Create a window for display.
imshow( "Display window", image ); // Show our image inside it.
waitKey(0); // Wait for a keystroke in the window
return 0;
}
I get the error statement:
Process finished with exit code -1073741515 (0xC0000135)
As for the content in my CMakeLists.txt, it looks like this:
cmake_minimum_required(VERSION 3.6)
project(test)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
# Where to find CMake modules and OpenCV
set(OpenCV_DIR "C:\\opencv\\mingw-build\\install")
set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CMAKE_SOURCE_DIR}/cmake/")
find_package(OpenCV REQUIRED)
include_directories(${OpenCV_INCLUDE_DIRS})
add_executable(openCV main.cpp)
# add libs you need
set(OpenCV_LIBS opencv_core opencv_imgproc opencv_highgui opencv_imgcodecs)
# linking
target_link_libraries(openCV ${OpenCV_LIBS})
Thanks for helping me with this.
You need to add OpenCV binary path with DLLs to your PATH BEFORE CLion start.
I do it from script:
=== CLionWithMingwAndOpenCV.bat ==========================
#echo off
set PATH=C:\mingw-w64\x86_64-5.2.0-win32-seh-rt_v4-rev0\mingw64\bin;D:\opencv\release\bin;%PATH%
"C:\Program Files (x86)\JetBrains\CLion XXXX\bin\clion64.exe"
=== ==========================
I'm going for absolute minimalism here. (It's been a while since I've worked with the Lua C API.)
#include <lua.hpp>
#include <iostream>
#include <string>
using namespace std;
int main(int argc, char** argv)
{
lua_State* state = luaL_newstate();
luaL_openlibs(state);
string input;
while (getline(cin, input))
{
auto error = luaL_dostring(state, input.c_str());
if (error)
{
cerr << "Lua Error: " << lua_tostring(state, -1) << '\n';
lua_pop(state, 1);
}
}
lua_close(state);
return 0;
}
This program works fine as long as I feed it perfect Lua. However, if I enter something bad (such as asdf()), the program crashes! Why is it not handling my error gracefully?
I've tried breaking out the calls before. It crashes on the call to lua_pcall itself. I never make it past that line.
The binary download (5.2.1 I believe) has a bug that was corrected in 5.2.3. I rebuilt the library from source, and now my program works fine.
I've been trying to find a way of grabbing video directly from an X window and got pointed to Xlib and the compositing extension.
So far, I've been able to listen to change events and grab a Pixmap with this code:
#include <X11/Intrinsic.h>
#include <X11/extensions/Xcomposite.h>
#include <X11/extensions/Xdamage.h>
#include <iostream>
#include <fstream>
using namespace std;
int main(int argc, char ** argv) {
int br, base;
Window win = 0x3400003;
Display *dsp = XOpenDisplay(0);
XCompositeQueryExtension(dsp, &base, &br);
XDamageQueryExtension(dsp,&base, &br);
cout << base << endl;
Damage damage = XDamageCreate(dsp, win, XDamageReportRawRectangles);
XCompositeRedirectWindow(dsp, win, CompositeRedirectAutomatic);
XEvent ev;
while(true) {
XNextEvent(dsp, &ev);
if(ev.type == base + XDamageNotify) {
Pixmap pm = XCompositeNameWindowPixmap(dsp, win);
XWindowAttributes attr;
XGetWindowAttributes(dsp, win, &attr);
XWriteBitmapFile(dsp, "test.bmp", pm, attr.width, attr.height, -1, -1);
return 0;
}
}
XCompositeUnredirectWindow(dsp, win, CompositeRedirectAutomatic);
XDamageDestroy(dsp, damage);
return 0;
}
The problem here is that the resulting bmp (created by XWriteBitmapFile) is black&white horribleness. Disregarding the fact that I don't want to write the data to file anyway, I am apparently doing something wrong in reading it.
I would love to convert the Pixmap to either a framebuffer in opengl or a binary blob in ram.
Thanks in advance for any help you can give me on this.
Best regards.
"Bitmaps" in X world refer to two-colored images. I guess XWriteBitmapFile does internally GetImage request and transforms server pixmap to a bitmap. Note that file format is it's own 'X11 bitmap', not windows bitmap.
Use XGetImage function If you actually need image's binary blob.
I am trying to use a stringstream object in VC++ (VStudio 2003) butI am getting an error when I use the overloaded << operator to try and set some manipulators.
I am trying the following:
int SomeInt = 1;
stringstream StrStream;
StrStream << std::setw(2) << SomeInt;
This will not compile (error C2593: 'operator <<' is ambiguous).
Does VStudio 2003 support using manipulators in this way?
I know that I can just set the width directly on the stringstream object e.g. StrStream.width(2);
I was wondering why the more usual method doesn't work?
Are you sure you included all of the right headers? The following compiles for me in VS2003:
#include <iostream>
#include <sstream>
#include <iomanip>
int main()
{
int SomeInt = 1;
std::stringstream StrStream;
StrStream << std::setw(2) << SomeInt;
return 0;
}
I love this reference site for stream questions like this.
/Allan
You probably just forgot to include iomanip, but I can't be sure because you didn't include code for a complete program there.
This complete program works fine over here using VS 2003:
#include <sstream>
#include <iomanip>
int main()
{
int SomeInt = 1;
std::stringstream StrStream;
StrStream << std::setw(2) << SomeInt;
}