Open the Brushes Window
If you go to Window>Brushes a new window will open where you can customise the brush you're using.
The first option lets you dynamically change the size of your brush. If you click on Shape Dynamics so the box gets ticked and it turns blue, you'll be able to change various options to change the way your brush works.
You'll find the word jitter used quite a lot and you're probably wondering what does it mean? Well the easiest description we could think of is jitter is a way to describe how Photoshop randomly changes the alterations you're making to the size, angle etc, on each of the brush strokes you apply.
It can never make a brush stroke/shape bigger than what you've set but it can pick from any number bellow it. If you want to restrict the jitter further, change the minimum slider as this gives Photoshop a bottom value it can't go under. For example, our size jitter is set to 26% which could mean Photoshop can pick random figures from 0-26% but by changing the Minimum Diameter to 14% it now knows it can only pick from 14-26%. To adjust the values, either use the sliders or input a value directly into the box.
You can adjust the size, angle and roundness of the jitter under Shape Dynamics. Take a look at these before and after examples to see how changing the shape dynamics changes the brush and the effect it creates:
Next there's Scattering. Again, by clicking on it so it turns blue and the tick box is ticked, you'll bring up several options that you can change.
Above Left: No changes to the Scattering. Above Right: With Scatter Applied.
By changing the scatter value, you will alter how spread out the shapes are once you begin making brush strokes on your image. The higher the percentage (the more you pull the slider to the right) the more scattered the pattern will be. By increasing the Count figure you're telling Photoshop you want more shapes to be added with every brush stroke and Count Jitter will change the positioning of the shapes, making the pattern more random.
Texture and Dual Brush
Following Scattering there's Texture and Dual Brush. Texture lets you add a texture to the brush while Dual Brush combines two different brushes together which you can paint with at the same time.
Again, you can adjust the Diameter, Spacing, Scatter and Count of the brush. You can also adjust the blend mode to change how the two brushes blend together. If you want to randomly change the orientation of the brush, tick Flip so the second brush is flipped occasionally when you paint. The second brush does get applied to the top of your other brush strokes though so is only really useful if you want shapes cutting out of the original brush you picked.
We take a step away from changing the shape of the brush to altering its colour. You can change the colour of your brush by changing your foreground and background colours which you can further adjust with the Colour Dynamic options in the brushes window. As this image shows:
Finally, you can adjust the Opacity and Flow of the shapes you're applying in the Other Dynamics window.
Opacity will change the transparency of your brush while Flow will alter how much 'paint' the brush puts on to your canvas. It's an easy way to change the look of the jitter Photoshop creates.
Top: No changes made to the Opacity or Flow. Bottom: Slight adjustment to the Flow and Opacity.
If you're wondering why you'd want to customise your brushes, have a look at one of our previous tutorials where we've used a custom brush to give the impression that music notes are falling away from the neck of an instrument: Using Custom Brushes