Today’s Question: Sometimes, especially when working on graphic elements in a photo composition, I use the Pencil tool instead of the Brush tool to add or cleanup small areas. When I increase the brush size for the Pencil tool a little bit, the brush shape becomes more of a cross instead of a square, and then it starts to turn into a jagged circle. Is there a way to force the Pencil tool to have a square brush shape when I enlarge it?
Tim’s Quick Answer: The solution here is to use a brush with a square shape rather than a round shape. That will enable you to have a square shape for the Pencil tool at any brush size.
More Detail: The Pencil tool is really just a variation on the Brush tool but with a brush that always has a hard edge to it. The behavior described in today’s question really relates to the fact that the current brush is round, but without a soft transition at the edge. This created the jagged appearance due to the lack of anti-aliasing for the circular shape created with square pixels.
You can, however, employ a square brush. Photoshop even includes a set of square brushes you can use. Start by choosing the Pencil tool, and then click on the brush popup toward the far left of the Options bar (just to the right of the popup for the tool presets). On the brush popup that appears, click on the gear icon at the top-right of the popup. Then choose Square Brushes from the popup. I recommend choosing the “Append” option in the dialog that appears, so that the additional brushes will be added to the existing set, rather than replacing them.
You can then choose one of the square brush shapes that will be available now on the brush popup on the Options bar. Then, when you resize the brush (using the left and right square bracket keys: [ and ]) the brush shape will still be perfectly square, just at a different size.
Note, by the way, that you can get the same behavior as the Pencil tool by using the Brush tool instead, and setting the Hardness value to the brush to 100%.