Modify image to have round corners

Can't find any example of doing it. I need to take ready image and add some radius, also have the rest of the corners transparent.

Any ideas ?
Thanks

In case somebody will need it.

Code:

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QImage image("image.png");
 
QImage out(image.width(), image.height(), QImage::Format_ARGB32);
out.fill(Qt::transparent);
 
QBrush brush(image);
 
QPen pen;
pen.setColor(Qt::darkGray);
pen.setJoinStyle(Qt::RoundJoin);
 
QPainter painter(&out);
painter.setBrush(brush);
painter.setPen(pen);
painter.drawRoundedRect(0, 0, image.width(), image.height(), 20, 20);
 
out.save("image.png", "PNG", 100);

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