The Blur/Sharpen tool uses the current brush to locally blur or sharpen your
image. Blurring with it can be useful if some element of your image stands
out too much, and you would like to soften it. If you want to blur a whole
layer, or a large part of one, you will probably be better off using one
of the Blur Filters.
The direction of a brushstroke has no effect: if you want directional
blurring, use the Smudge tool.
In “Sharpen” mode, the tool works by increasing the contrast
where the brush is applied. A little bit of this may be useful, but
over-application will produce noise. Some of the
Enhancement Filters, particularly
the Unsharp Mask, do a
much cleaner job of sharpening areas of a layer.
![[Tip]](images/tip.png)
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Tip |
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You can create a more sophisticated sharpening brush using the Clone
tool. To do this, start by duplicating the layer you want to work on,
and run a sharpening filter, such as Unsharp Mask, on the copy. Then
activate the Clone tool, and in its Tool Options set Source to
“Image source” and Alignment to “Registered”.
Set the Opacity to a modest value, such as 10. Then Ctrl-click on the
copy to make it the source image. If you now paint on the original
layer, you will mix together, where the brush is applied, the sharpened
version with the unsharpened version.
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Both blurring and sharpening work incrementally: moving the brush
repeatedly over an area will increase the effect with each additional
pass. The Rate control allows you to determine how quickly the
modifications accumulate. The Opacity control, however, can be used to
limit the amount of blurring that can be produced by a single brushstroke,
regardless of how many passes are made with it.
3.13.1. Activating the Tool
There are different possibilities to activate the tool:
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From the image-menu:
→ → .
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The Tool can also be called by clicking the tool icon:
in the Toolbox.
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By using the keyboard shortcut ShiftU.
3.13.2. Key modifiers (Defaults)
See the Brush Tools
Overview for a description of key modifiers that have the
same effect on all brush tools.
Normally, tool options are displayed in a window attached under the
Toolbox as soon as you activate a tool. If they are not, you can access
them from the image menu bar through
→ → which opens the option window of the selected tool.
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Opacity; Brush; Scale; Brush Dynamics; Fade Out; Apply Jitter;
Hard Edges
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![[Note]](images/note.png)
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Note |
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See the Brush Tools
Overview for a description of tool options that apply to many or
all brush tools.
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Convolve Type
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Blur
mode causes each pixel affected by the brush to be blended with
neighboring pixels, thereby increasing the similarity of pixels
inside the brushstroke area. Sharpen
mode causes each pixel to become more different from its neighbors
than it previously was: it increases contrast inside the
brushstroke area. Too much Sharpen ends in an ugly flocculation
aspect. Whatever setting you choose here, you can
reverse it on-the-fly by holding down the Ctrl key.
“Convolve” refers to a mathematical method using
matrices.
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Rate
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The Rate
slider sets the strength of the Blur/Sharpen effect.
