The simple trick to create Rounded corners in Photoshop for 'L' shaped rectangle

The simple trick to create Rounded corners in Photoshop for 'L' shaped
rectangle
1.Create New Channel and draw 'L' shape rectangle in white color
2.Apply Gaussian Blur Filter value=5
3.Apply LEVELS value shadow=120, midtone=0, highlight=150
4.Select channel by Ctrl+Click the channel and fill it with your favourite color in the layer