#include <QCoreApplication>
#include <QDir>
#include <QPixmap>
#include <QDebug>

QStringList getAllEntryList(QDir dir, const QStringList &nameFilters, QDir::Filters filters)
{
    QStringList list;
    for(QString filename : dir.entryList(nameFilters, filters))
        list.append(dir.filePath(filename));
    for(QString dirname : dir.entryList(QDir::AllDirs | QDir::NoDotAndDotDot))
    {
        QDir subdir(dir);
        subdir.cd(dirname);
        list.append(getAllEntryList(subdir, nameFilters, filters));
    }
    return list;
}

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    QStringList list = getAllEntryList(QDir(a.arguments().value(1)), QStringList("*.png"), QDir::Files|QDir::NoDotAndDotDot);

    for(int i = 0; i <= list.size(); ++i)
    {
        QPixmap pic(list[i], "PNG");
        qDebug()<<pic.save(list[i], "PNG")<<i<<list[i];
    }

    return 0;
}