9.8. Erodovat

9.8.1. Overview

Obrázek 17.187. Applying example for the Erode filter

Applying example for the Erode filter

Original image

Applying example for the Erode filter

Filter Erode applied

Tento filtr rozšiřuje a zvýrazňuje tmavé části aktivní vrstvy nebo výběru.

For every image pixel, it brings the pixel Value (luminosity) into line with the lowest Value (the darkest) of the 8 neighboring pixels (3×3 matrix). So, a dark pixel is added around dark areas. An isolated pixel on a brighter background will be changed to a big pixel, composed of 9 pixels, and that will create some noise in the image.

In this image, the studied pixel has a red border and the studied 3×3 matrix has a green border. Thus when the pixel marked with I is inside the green border, the studied pixel turns to black.

A larger dark area will expand by one pixel in all directions:

Filtr byl aplikován třikrát.

On more complex images, dark areas are widened and enhanced the same, and somewhat pixelated. Here, the filter was applied 3 times:

Samozřejmě, pokud je pozadí tmavší než popředí, pokryje celý obrázek.

9.8.2. Activating the Filter

This filter is found in the image window menu under FiltersGenericErode.

9.8.3. Příklady

Obrázek 17.188. Erode text

Erode text