10.13.  Value Propagate

Revision History
Revision $Revision: 1934 $ 2007-05-05 j.h

10.13.1.  Overview

You can find this filter through FiltersDistortsValue Propagate.

It works on color borders. It spreads pixels that have a Value between selected thresholds, in selected directions.

10.13.2.  Options


The result of your settings will appear in the Preview without affecting the image until you click on OK.

Propagate Mode

The examples will be about the following image (zoom x8):

Figure 15.156.  Original image

Original image

  • More White: Pixels will be propagated from upper Value pixels towards lower Value pixels. So bright areas will enlarge.

    Figure 15.157.  More White

    More White

    Bright pixels have been propagated to dark pixels in the four directions : top, bottom, right and left. Filter applied several times to increase effect.

  • More Black: Pixels will be propagated from lower Value pixels towards upper Value pixels. So dark areas will enlarge.

    Figure 15.158.  More Black

    More Black

    Figure 15.159.  To bottom only

    To bottom only

    The same as above with To bottom direction only checked.

  • Middle Value to Peaks: On a border between the selected thresholds, the average of both values is propagated.

    Figure 15.160.  Middle Value to Peaks Middelverdi til spissane

    Middle Value to Peaks Middelverdi til spissane

    A thin border with a transitional color has been added to objets. It is not visible around objects with smoothed borders.

    Middle Value to Peaks Middelverdi til spissane

    Green area zoomed x800. A thin border (one pixel wide) has been added. Its value is the average between grey (90%) and green (78%) : (90 + 78) / 2 = 84.

  • Foreground to Peaks: The propagated areas will be filled with the foreground color of the toolbox.

    Figure 15.161.  Foreground to Peaks

    Foreground to Peaks

    In this example, the foreground color in Toolbox is Red. A thin border, one pixel wide, red, is added around objects. With smoothed objects, this border is located at the furthest limit of smoothing. Here, another border appears inside. This is an artefact due to the small size of the object which makes the smooting area of opposite sides to overlap.

  • Only Foreground: Only areas with the Toolbox Foreground color will propagate.

    Figure 15.162.  Only Foreground

    Only Foreground

    In this example, the foreground color in Toolbox is that of the green object. After applying filter several times, the green area is clearly enlarged.

  • Only Background: Only areas with the Background color will propagate.

  • More Opaque and More Transparent: These commands work like More White and More Black. Opaque (transparent) areas will be propagated over less opaque (transparent) areas. These commands need an image with an Alpha channel.

    Figure 15.163.  More opaque

    More opaque

    Original layer, with a transparent background.

    More opaque

    Filter applied several times: the green, opaque, area got increased.

Parameters Settings
Lower / Upper Threshold

Lower Threshold and Upper Threshold: These commands allow you to set the Value range that will be concerned by Propagate.

Propagating Rate

Propagating Rate: That's the propagating amount. The higher it will be the more colored the propagation will be.

Propagating Direction

Propagating Direction: You can select one or more directions.