### 3.2. Focus Blur

#### 3.2.1. Overview

Obrázek 17.9. The Focus Blur filter

Original image

Filter applied

Focus blur creates a blur in all directions around a focal point. The default focal point is the center of the layer or selection. You can change this focal point by dragging the center point. All other points and lines can also be dragged to adjust the shape and focus area of the image.

#### 3.2.2. Activating the Filter

This filter is found in the main menu under Filters → Blur → Focus Blur….

#### 3.2.3. Options

Obrázek 17.10. Focus Blur filter dialog options with Geometry Options expanded

Presets, „Input Type“, Clipping, Blending Options, Preview, Merge filter, Split view

  | Poznámka
  These options are described in 2 – „Common Features“.

Shape

  Here, you can select the shape used for creating the focus blur. The choices are Circle, Square, Diamond, Horizontal and Vertical.

Typ rozostření

  The type of blur to use. The choices are Gaussian Blur and Lens Blur. It will use the filters of the same name to do the actual blurring.

Poloměr rozostření

  The size of the out-of-blur radius.

High quality

  Generate more accurate and consistent output. This is slower.

  Only available when Blur Type is Gaussian Blur.

Highlight factor

  Relative highlight strength.

  Only available when Blur Type is Lens Blur.

Highlight threshold

  Here you can set the minimum and maximum values for highlighting. It can be set either by dragging the black and white triangles, or inputting exact values into the number entry fields.

  Only available when Blur Type is Lens Blur.

Geometry Options

  These geometry related options can all be changed by using the visual on-canvas controls. In case you need more fine-grained control, they can be set manually here.

  Center X, Center Y

    Specifies the center X and Y position of the focus blur.

  Poloměr

    The radius of the outer focus region. Visible as the outer continuous line.

  Sharpness

    The radius of the inner focus region. Visible as the inner continuous line.

  Midpoint

    The focus transition midpoint. Shown as a dashed line. The area from the inner (sharpness) line to the midpoint, is where the focus area turns into the blurred area.

  Aspect ratio

    This controls the aspect ratio.

  Rotation

    This controls the rotation in degrees. You can either use the circular control or enter numbers.

On-canvas controls

  This option (default) allows you to modify blur settings directly on canvas, for easier visual tweaking of blur settings. It displays lines in the selected shape with points on it. Both the lines and the points can be dragged with a mouse to change the focus center, the blurring area and other settings that are also available in the Geometry Options.

3. Filtry rozostření |  | 3.3. Gaussovo rozostření

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