How to Smudge Effectively in Photoshop

Photoshop's "Smudge" tool emulates the effect of smudging paint across a canvas.

Photoshop's "Smudge" tool emulates the effect of smudging paint across a canvas. Like most Photoshop tools, it is highly configurable: you can select different brush shapes and dynamics to emulate real paint brushes, change the size and "pressure" of the virtual brush, and control different channels and layers to include in the smudging effect. In addition to imitating painting techniques, the "Smudge" tool can be used to touch up photographs and create unique digital effects.

Instructions

1. Click the "Smudge" tool in the toolbar to select it. The fingertip symbol represents the "Smudge" tool. The tool shares a spot with the "Blur" and "Sharpen" tools, so look for a water droplet or triangle if you don't see the "Smudge" tool. Right-click the "Blur" or "Sharpen" tool, then click the "Smudge" tool to select it.

2. Right-click the "Smudge" tool symbol in the "Options" bar, then choose "Reset Tool" to get started. Move the cursor into the image, and note the size of the circular brush. Make the brush smaller by pressing the "[" key, and larger by pressing the "]" key. As you change the size, the number beneath the brush icon in the "Options" bar changes accordingly.

3. Right-click the brush icon in the "Options" bar, and use the sliders to precisely change the size and hardness of the tool. Hardness determines the relative strength of the smudging near the edge of the brush; at 100 percent hardness, the entire space covered by the brush will be smudged equally, but if the hardness is reduced, the edges of the brush will smudge to a lesser degree. The brush icon indicates reduced hardness by fading to grey around its edges.

4. Click and hold, then drag across the image and release the mouse button to test the "Smudge" tool. Try different size and hardness settings to see how they affect the smudging.

5. Click the arrow next to the "Strength" field in the "Options" bar, then use the slider to increase or decrease the brush strength. Strength is analogous to the downward pressure applied to a brush in a real painting. The minimum strength value, 1 percent, produces a very mild smudge, while a strength of 100 percent produces an unrealistic displacement of the image content beneath the brush. Experiment with different strength values in the image to see its effects.

6. Enable the "Finger Painting" check box in the "Options" bar to add the currently-selected foreground color to the smudge effect. This option is analogous to smudging a painting with a brush or finger that has been dipped into paint.

7. Enable the "Sample all layers" check box in the "Options" bar to smudge the content of all the visible layers beneath the brush, or keep it disabled to use only the content in the current layer. This will only smudge layer content that is actually visible, not layers totally obscured by the currently selected one. To see how this effect works, select and delete a section of the current layer, and make sure another layer is beneath it. Smudge around and over the deleted area with "Sample all layers" enabled and disabled.

8. Reveal the "Brush" panel if it's not already visible by clicking the symbol to the right of the brush icon in the "Options" bar. Many pre-made brushes are available, including ones intended to emulate real brushes, and fantastical ones only possible in Photoshop. Select a brush from the grid of icons in the right part of the panel, then adjust its properties with the controls below.

9. Enable the various options beneath the "Brush Tip Shape" to create advanced brush effects. For example, "Shape Dynamics" allows you modulate the size and/or rotation of the brush during a single stroke by using the mouse wheel, graphics tablet stylus orientation or another property such as stroke direction. These effects can be very subtle, so carefully experiment with each to get the effect you want. The preview display at the bottom of the "Brush" panel should give you an idea of the potential variations introduced by each option you enable. Not all options are compatible with all brushes.

10. Use the "Mode" drop-down menu in the "Options" bar to alter the smudging effect in terms of what content from the image is smudged. "Darken" and "Lighten" change the lightness of the smudged area. "Hue," "Saturation," "Color" and "Luminosity" are unrealistic effects, each smudging only certain channels of information across the image. Experiment with each to see what information is smudged.