6.3. Supernova

6.3.1. Overview

图 17.111. Applying example for the Supernova filter

Original image

Filter “Supernova” applied

This filter creates a big star reminding a super-nova. It works with RGB and GRAY images. Light effect decreases according to 1/r where r is the distance from star center.

6.3.2. Activate the filter

This filter is found in the image window menu under Filters → Light and Shadow → Supernova….

6.3.3. Options

图 17.112. “Supernova” filter options

Presets, “Input Type”, Clipping, Blending Options, Preview, Split view

	注意
	These options are described in 第 2 节 “Common Features”.

Center X, Center Y

You can use input boxes to set horizontal (X) and vertical (Y) coordinates of Supernova center. You can also click and drag the supernova center in preview.

Radius

This is radius of the Supernova center: the upper limit seems to be unlimited. When you increase the value, you increase the number of central white pixels according to r*r (1, 4, 9…).

Radius is represented by a horizontal line in preview, with a cross at end. You can click and drag this cross to set radius.

Number of spokes

This is number of rays (1-1024). Each pixel in the nova center emit one pixel wide rays. All these rays are more or less superimposed resulting in this glittering effect you get when you move this slider.

Random hue

Color rays at random. (0-360) value seems to be a range in HSV color circle.

Color

When you click on the color swatch, you bring up the usual color selector.

You also have a color picker. When it is selected, the mouse pointer goes with a square on image: it’s the color sample whose size you can modify in the GEGL operation window under Toolbox.

Random seed

Filter effect is made at random. You can change seed.