The patch tool is perfect when you need to retouch a large area. After you have created a Stamp Visible (Shift+Alt+Optn+E), make a selection around the area you would like changed. These areas will include skin blemishes, under eye bags, wrinkles, dark spots, scars etc. After making your selection, click and drag inside of the selection to a similar area that does not have any blemishes. Even though the Patch Tool is not perfect, sometimes the blending won’t look uniform. In this case the best option is to fade out the patch effect until it does blend smoothly.