How to read directory with images by VideoCapture?

edit

If you are working in Windows and don't want to use boost you can do it like that (include Windows.h beforehand):

WIN32_FIND_DATA found;
HANDLE hfind;

vector<Mat> images;
int fileCount=0; 

hfind=FindFirstFile("C:\\path\\baseFilename???.jpg",&found);
if(hfind!=INVALID_HANDLE_VALUE)
    do
    {
        fileCount++;
        images.push_back(imread(found.cFileName)); 
    }while(FindNextFile(hfind,&found));

Hope someone will find it useful. I wish VideoCapture worked like that. I mean, it would use wildcards and load all the files in the directory in alphabetical order even if some consecutive files are missing.

If your images have different size, be sure to capture the largest first (by naming it 001 e.g.), otherwise you may get a memory access fault. Further the step size is not adapted by VideoCapture (opencv 2.4.2.). After

 cap >> Img;

you may need

 // correct false step size for images of different size
 Img.step = Img.elemSize()*Img.cols;

I had a similar need as you did, I solved the problem with boost filesystem library.

For file scanning with boost, it would look something like this:

int scanFiles( const path & directory, string filterFileType)
{   
    int fileCount=0;
    if( exists( directory ) )
    {
        directory_iterator end ;
        for( directory_iterator iter(directory) ; iter != end ; ++iter )
            if ( (is_regular_file( *iter ) && iter->path().extension().string() == filterFileType))
        {                               
            cout << iter->path().filename().string() << endl ; //this is the one of scanned file names
            fileCount++;
        }
    }   
    return fileCount;
}

Basically what that function does (at least in my app), returns the count of files with a specified extension. So scanFiles("labels", "png"); will return me the number of png files in directory labels.

While scanning you can return or update global Mat variable and use it to do your stuff.

But I don't think that OpenCV can scan through files natively.