Acest filtru lărgește și îmbunătățește zonele întunecate ale stratului sau selecției active.

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:

Filtrul a fost aplicat de 3 ori.

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

Desigur, dacă fundalul este mai întunecat decât prim-planul, acesta va acoperi întreaga imagine.

This filter is found in the main menu under Filters → Generic → Erode.