From sharp edges to smooth round ones...
Create a new layer in your document with a shape with sharp edges;

Get the Magic Wand-tool and select the black (or whatever color you have...);

GOTO WINDOW>CHANNELS and click this button in the pop-up;

You should see a black and white-image of your shape;
Now GOTO FILTER>BLUR>GAUSSIAN BLUR and add a blur that makes the edges quite round;

Press CTRL+L and set it to this: (NOTE: This depends on how big your blur was.. Try to get the arrows in the middle eather way.)


Select the shape with the Magic Wand-Tool and click on the top layer of your Channels-popup;

Fill the selection with any color and delete the layer with the sharp edges;

Now add any layer-style needed for your round shape...









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