### 6.5. Gradient Flare

#### 6.5.1. Overview

Figure 17.116. Example for the Gradient Flare filter

Original image

Filter applied

Gradient Flare effect reminds the effect you get when you take a photograph of a blinding light source, with a halo and radiations around the source. The Gradient Flare image has three components: Glow which is the big central fireball, Rays and Second Flares

| Note
If the image is in indexed mode, this menu entry is disabled.

#### 6.5.2. Activating the Filter

This filter is found in the main menu under Filters → Light and Shadow → Gradient Flare….

#### 6.5.3. Options

The Settings tab allows you to set manually the parameters while the Selector tab let you choose presets in a list.

Preview

  When Auto update preview is checked, parameter setting results are interactively displayed in preview without modifying the image until you click on OK button.

##### 6.5.3.1. Settings

Figure 17.117. “Gradient Flare” filter options (Settings)

Center

  You can set the X and Y (pixels) coordinates using the input box or by clicking in the preview. The coordinate origin is at the upper left corner.

Parameters
  Radius

    The radius of the effect. The slider limits the range of possible values, but using the input box you can enter greater values.

  Rotation

    Turn the effect.

  Hue rotation

    Change the tint (color) of the effect.

  Vector angle

    Turn the Second flares.

  Vector length

    Vary the distance applied for the Second flares.

Adaptive supersampling

  When enabled, adaptive supersampling, an anti-aliasing technique, is used when rendering the image. See Supersampling for more information.

  Enabling this setting activates the following options that can be used to adjust the supersampling.

  Max depth

    Specifies the maximum depth for supersampling. This determines the number of samples used. Higher values may produce better results, but can potentially slow down the computation.

  Threshold

    Specifies the lower threshold of pixel difference that stops supersampling.

##### 6.5.3.2. Selector

Figure 17.118. “Gradient Flare” filter options (Selector)

The Selector tab allows you to select a Gradient Flare pattern, to change it and save it.

New

  When you click on this button, you create a new Gradient Flare pattern. Give it a name of your choice.

Edit

  This button brings up the Gradient Flare Editor (see below).

Copy

  This button allows you to duplicate selected Gradient Flare pattern. You can edit the copy without altering the original.

Delete

  This button deletes the selected Gradient Flare pattern.

#### 6.5.4. Gradient Flare Editor

The Gradient Flare Editor is also organized in tabs:

##### 6.5.4.1. General

Figure 17.119. “Gradient Flare Editor” options (General)

Glow Paint Options
  Opacity

    Slider and input box allows you to reduce glow opacity (0-100).

  Paint mode

    You can choose between four modes:

    Normal

      In this mode, the glow covers the image without taking into account what is beneath.

    Addition

      Pixel RGB values of glow are added to RGB values of the corresponding pixels in the image. Colors get lighter and white areas may appear.

    Overlay

      Light/Dark areas of glow enhance corresponding light/dark areas of image.

    Screen

      Dark areas of image are enlightened by corresponding light areas of glow. Imagine two slides projected onto the same screen.

Rays Paint Options

  Options are the same as for GlowPaintOptions.

Second Flare Paint Options

  Options are the same as for GlowPaintOptions.

##### 6.5.4.2. Glow

Figure 17.120. “Gradient Flare Editor” options (Glow)

Gradients

  By clicking on the rectangular buttons, you can develop a long list of gradients. “%” gradients belong to the Editor.

  Radial gradient

    The selected gradient is drawn radially, from center to edge.

  Angular gradient

    The selected gradient develops around center, counter-clockwise, starting from three o'clock if the Rotation parameter is set to 0. Radial and angular gradients are combined according to the Multiply mode: light areas are enhanced and colors are mixed according to CMYK color system (that of your printer).

  Angular size gradient

    This is a gradient of radius size which develops angularly. Radius is controlled according to gradient Luminosity: if luminosity is zero (black), the radius is 0%. If luminosity is 100% (white), the radius is also 100%.

Parameters
  Size (%)

    Sets size of glow in percent (0-200).

  Rotation

    Sets the origin of the angular gradient (-180 +180).

  Hue rotation

    Sets glow color, according to the HSV color wheel (-180 +180). (Cf. The triangle color selector.)

##### 6.5.4.3. Rays

Figure 17.121. “Gradient Flare Editor” options (Rays)

Gradients

  The options are the same as for Glow.

Parameters

  The first three options are the same as in Glow. Two are new:

  # of Spikes

    This option determines the number of spikes (1-300) but also their texture.

  Spike thickness

    When spikes get wider (1-100), they look like flower petals.

##### 6.5.4.4. Second Flares

Figure 17.122. “Gradient Flare Editor” options (Second Flares)

Gradients

  The options are the same as for Glow.

Parameters

  The options are the same as for Glow.

Shape of Second Flares

  Second flares, these satellites of the main flare, may have two shapes: Circle and Polygon. You can set the Number polygon sides. The option accepts 1 side (!), not 2.

Random seed, New Seed

  This option controls the randomness of the filter. The Random seed box lets you manually enter a seed for the randomization algorithm used. You can also generate a random seed by pressing the New Seed button. If the same random seed is used in the same situation, the filter produces exactly the same results. A different random seed produces different results.

Randomize

  When you click on this button, you produce a random seed that will be used by the random generator. It is each time different.

6.4. Lens Flare |  | 6.6. Lighting Effects

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