Operation Manual

Sharpen graphic filter
Clicking on the Sharpen icon sharpens the image by applying a high pass filter, increasing the
contrast between neighboring pixels emphasizing the difference in brightness. This will accentuate
the outlines and the effect will be strengthened if you apply the filter several times (Figure 144).
Remove noise graphic filter
Clicking on the Remove Noise icon removes noise by applying a median filter by comparing
every pixel with its neighbors. It then replaces extreme values of those pixels that deviate in color
by a large amount from a mean value by a pixel with a mean color value. The amount of picture
information does not increase, but because there are fewer contrast changes resulting in a graphic
that looks smoother (Figure 145).
Figure 145: Remove Noise graphic filter
Figure 146: Solarization graphic filter
Figure 147: Solarization dialog
Solarization graphic filter
Solarization is a phenomenon in photography in which the image recorded on a negative or on a
photographic print is wholly or partially reversed in tone. Dark areas appear light or light areas
appear dark. Solarization was originally a photochemical effect used during photographic film
126 LibreOffice 4.3 Draw Guide