It’s seven steps in total and is prone to being inaccurate; plus, the radius of the corners can’t be changed on the fly. Applying levels can also be a bit fiddly. One advantage is that different levels settings can be used to obtain different degrees of antialiasing, from incredibly soft to completely aliased.
- Create a new layer
- Draw a rectangular selection
- Enter quick mask (Q)
- Gaussian blur by half the radius that you’d like for the rounded corners. (For example, a 10-pixel radius would need a 5-pixel blur.)
- Apply Levels (Command + L), and use about 118 for the black point and 137 for the white point on the input levels
- Exit quick mask (Q)
- Fill selection
On the positive side, this blur method can be used to quickly create some interesting and organic shapes that would be difficult to draw by hand. The circles method is very accurate and easily reproducible, but has a whopping 13 steps. That’s a lot of clicking for just a single roundrect.
- Create a new layer
- Make a circular selection that is twice as large as the radius you would like (for example, a 10-pixel radius would require a 20×20-pixel circle)
- Fill the selection
- Move the selection right. This can be done quickly by holding down Shift and pressing the right-arrow key a few times
- Fill the selection
- Move the selection down
- Fill the selection
- Move the selection left
- Fill the selection
Conclusion
Make a rectangular selection that covers the entire vertical span of the roundrect but that starts and ends halfway through the circles at the ends
