9.3. Distance Map

9.3. Distance Map
	9. Generic Filters

9.3.1. Overview

Each pixel in the image is replaced with a gray value dependent on the distance to the nearest obstacle pixel, generally a boundary pixel. Different methods can be used to calculate the distance.

9.3.2. Activating the filter

This filter is found in the image window menu under Filters → Generic → Distance Map….

9.3.3. Options

Figuur 17.172. “Distance Map” options

Presets, Preview, Split view

	Opmerking
	These options are described in Paragraaf 2, “Common Features”.

Metric

“Metric” is a topology term. Three methods are available:

Euclidean default: the distance is a line.
Manhattan
Chebyshev

Threshold low

Default is 0. Increasing this value selects higher lightness pixels

Original image for examples. Threshold low will be progressively increased. Lightness: dark red = 0.070; bright red = 0.223; green = 0.133

Figuur 17.173. “Threshold low” example

Threshold low = 0: only border distances are visible.

Threshold low = 0.070: “dark red” circle appears.

Threshold low = 0.133: “green” circle appears.

Threshold low = 0.223: “bright red” circle appears.

Threshold high

Default is 100. Decreasing this value makes result lighter.

Grayscale Averaging

Number of computations for grayscale averaging.

Normalize

This option is checked by default. If you uncheck it, no blur is created.

Figuur 17.174. “Normalize” example

Normalize option checked.

Normalize option unchecked.

Clipping

The result of this filter can be larger than the original image. With the default Adjust option, the layer will be automatically resized as necessary when the filter is applied. With the Clip option the result will be clipped to the layer boundary.

9.3.4. Using Distance Map filter

Searching for an example using Distance map filter in image processing...