Adobe Digital Imaging How-Tos: Using the Mixer Brush
Hopefully, you now have a better understanding of how Bristle Tips differ from normal brush presets, but it's important to look at the other side of the equation. The Mixer Brush goes a long way toward achieving many of the painting effects that can be created in programs like Corel Painter, but with a fraction of the learning curve. The secret of the Mixer Brush is that it treats color pixels like real paint; this means that you can blend colors in new ways and create new kinds of brushstrokes that previously were not possible.
To access the Mixer Brush (which shares a group with the standard Brush tool), press B or Shift-B to cycle through the group. The Mixer Brush icon displays a small paint droplet with a brush, . When you select the Mixer Brush, the Options bar populates with sever al settings for controlling the "digital paint" in your photo (Figure 86a). The most important settings for getting started are described in more detail in the following sections.
Figure 86a The new Mixer Brush settings in the Options bar.
This setting mimics the process of paint accumulating among the bristles and on the surface of a paintbrush. To use brush loading, click the Load Brush button on the Options bar, and increase the Load slider value before you paint.
As a photographer, when painting over photos, I prefer not to load the brush so that as I paint a specific area of detail, only the colors from that area are mixed and moved on the canvas. This is of course a subjective decision; like real painting, there are no strict rules.
Photoshop offers the option to clean off the digitally simulated paintbrush each time you pick up the stylus. To clean the brush after each stroke, click the Clean Brush button. To create a more organic-looking painting or if you're painting to an empty canvas, you may want to leave this setting off and clean the brush manually by opening the Current Brush Load pop-up and choosing Clean Brush (Figure 86b).
Figure 86b The Current Brush Load pop-up menu provides options for manually cleaning and loading the brush as you paint.
The Wet setting describes the viscosity or "wetness" of the digital pixels that you'll be spreading across the canvas. Like real paintings, the less dry the paint is, the more it can be spread across the canvas, mixing with other colors and textures as you do so. Figure 86c shows brushstrokes that use (from left to right) a Wet value of 10%, 50%, and 100%. The Bristle Tip settings and all other Mixer Brush settings were the same.
Figure 86c The Wet slider helps to set up the characteristic of the simulated paint, whether it is dry or very wet, allowing the pixels to spread and mix colors more easily.
This setting defines the mix ratio or the tendency of the colors on the canvas to mix together as you brush over them, creating new colors. When using real paints, certain types mix to create new colors, while others tend to cover up underlying colors, depending on the mediums used and other variables. Figure 86d shows brushstrokes that use (from top to bottom) a Mix value of 0%, 40%, and 80%. All other settings were the same.
Figure 86d The Mix slider helps to define the amount of color mixing that occurs as you move your brush across the image.
The Flow defines the amount or "density" of the simulated paint that's being put down on the canvas. The higher the value, the denser the paint will be, and the colors and details underneath will show through less.
The easiest way to get started with the Mixer Brush is to click the Useful Combinations pop-up menu (Figure 86e). It combines four paint states (Dry, Moist, Wet, and Very Wet) with three levels of paint loading or mixing (Medium, Light, and Heavy). The Medium Mix options are the first in each series.
Figure 86e The Blending Combinations pop-up menu makes it very easy to begin experimenting with the Mixer brush and understanding how it uses the Wet, Mix, and Load values to simulate paint being spread across a canvas.
For photo-painting, my usual process is to create an empty layer over the Background (so I'm not painting on the original). Make sure the Sample All Layers option is turned on. Then I use either the Moist or Wet presets, with either normal or heavy mix settings. From there, I use a smaller, more fine-tipped brush and short brushstrokes that make it easy to follow the contours of fine details, while using broader brush tips and longer strokes when working with large areas of homogenous texture like skies or water (Figure 86f).
Figure 86f Examples of painterly effects that can be achieved with the Bristle Tips and Mixer Brush.