Opening results

In the first example we see how opening removes 'salt'-noise. Opening the following image with a 3x3 kernel,

gives:

When an image has 'salt-and-pepper'-noise, we see how opening only removes the 'salt'-noise. Opening the following image with a 3x3 kernel,

gives,

Opening the following image with a 3x9 kernel,

gives us the horizontal lines only :

Note that there are a few glitches in this last image where the diagonal lines cross vertical lines. These could easily be eliminated, however, using a slightly longer structuring element.

Graylevel opening can similarly be used to select and preserve particular intensity patterns while attenuating others. As a simple example we start with

and then perform graylevel opening with a flat 5×5 square structuring element to produce

The important thing to notice here is the way in which bright features smaller than the structuring element have been greatly reduced in intensity, while larger features have remained more or less unchanged in intensity. Thus the fine grained hair and whiskers in the image have been much reduced in intensity, while the nose region is still at much the same intensity as before. Note that the image does have a more matt appearance than before since the opening has eliminated small specularities and texture fluctuations.

[Dilationresults] [Erosionresults] [Closingresults]