### 6.6. Lighting Effects

#### 6.6.1. Overview

Figure 17.123. The same image, before and after applying Lighting filter

Original image

Filter applied

This filter simulates the effect you get when you light up a wall with a spot. It doesn't produce any drop shadows and, of course, doesn't reveal any new details in dark zones.

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

#### 6.6.2. Activating the Filter

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

#### 6.6.3. Options

Figure 17.124. “Lighting” filter options

Preview

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

  If Interactive is not checked, changes are displayed in preview only when you click on the Update button. This option is useful with a slow computer.

Any other options are organized in tabs:

##### 6.6.3.1. General Options

Figure 17.125. “Lighting” filter options (General Options)

Transparent background

  Makes destination image transparent when bumpmap height is zero (height is zero in black areas of the bumpmapped image).

Create new image

  Creates a new image when applying filter.

Antialiasing

  Enabling this setting allows you to remove or reduce the aliasing effect that can show up on borders.

  For more information, see Anti-aliasing in the Glossary.

Distance

  You can specify the distance of the light source from the center of the image with this slider. The range of values is from 0.0 to 2.0.

##### 6.6.3.2. Light Settings

Figure 17.126. “Lighting” filter options (Light Settings)

In this tab, you can set light parameters. With Light1 to Light6 you can create six light sources and work on each of them separately.

Type

  The filter provides several light types in a drop-down list:

  None

    This deletes the light source (light may persist).

  Directional

    The blue point is linked to preview center by a line which indicates the direction of light.

  Point

    Displays a blue point at center of preview. You can click and drag it to move light all over the preview.

  Spot

    Displays a blue point that cannot be moved. This light has a fixed direction.

Color

  When you click on the color swatch, you bring a dialog up where you can select the light source color.

Intensity

  With this option, you can set light intensity.

Position

  Determines the light point position according to three coordinates: X coordinate for horizontal position, Y for vertical position, Z for source distance (the light darkens when distance increases). Values are from -1 to +1.

Direction

  This option should allow you to fix the light direction in its three X, Y and Z coordinates.

Isolate

  With this option, you can decide whether all light sources must appear in the Preview, or only the source you are working on.

Lighting presets

  You can save your settings with the Save and get them back later with the Open.

##### 6.6.3.3. Material Properties

Figure 17.127. “Lighting” filter options (Material Properties)

These options don't concern light itself, but light reflected by objects.

Small spheres, on both ends of the input boxes, represent the action of every option, from its minimum (on the left) to its maximum (on the right). Help pop ups are more useful.

Ambient intensity

  This option, also known as glowing, controls the amount of the original color to show where no direct light falls.

Diffuse intensity

  This option, also known as brightness, controls the intensity of the original color to show when hit directly by a light source.

Diffuse reflectivity

  This option controls how intense the light from the original color will be reflected.

Specular reflectivity

  This option controls how intense the highlight will be.

Highlight

  This option adjusts the polish or highlight. Higher values make the highlight more focused.

Metallic

  When this option is checked, surfaces look metallic.

##### 6.6.3.4. Bump Map

Figure 17.128. “Lighting” filter options (Bump Map)

In this tab, you can set filter options that give relief to the image. See Bump mapping .

Enable bump mapping

  With this option, bright parts of the image will appear raised and dark parts will appear depressed. The aspect depends on the light source position.

Bump map image

  Select a grayscale image to use as a bump map. See the Bump Map filter for more information.

Curve

  This option defines the method that will be used when applying the bump map; that is, the bump height is a function of the specified curve. Four curve types are available: Linear, Logarithmic, Sinusoidal and Spherical.

Maximum height

  This is the maximum height of bumps.

##### 6.6.3.5. Environment Map

Figure 17.129. “Lighting” filter options (Environment Map)

Enable environment mapping

  When you check this box, the following option is enabled:

Environment map image

  Select a RGB image to be used as environment map. Please note that for this option to work you should load another image with GIMP before using it.

  An example can be found at [BUDIG01].

6.5. Gradient Flare |  | 6.7. Sparkle

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