QImage saveImage(QSize(imageWidth,imageHeigth),QImage::Format_RGB888);
QFile file(filePath);
if (!file.open(QIODevice::ReadWrite))
    {
        return false;
    }
QByteArray ba;
QBuffer buffer(&ba);
buffer.open(QIODevice::WriteOnly);
saveImage.fill(QColor(Qt::black).rgb());
saveImage.save(&buffer,"JPG");
file.write(ba);
file.close();
buffer.close();