This filter is found in the image window menu under
→ → ."LIC" stands for Line Integral Convolution, a mathematical method. Plug-in author uses mathematical terms to name his options... This filter is used to apply a directional blur to an image, or to create textures. It could be called "Astigmatism" as it blurs certain directions in the image.
It uses a blur map. Unlike other maps, this filter doesn't use grey levels of this blur map. Filter takes in account only gradient direction(s). Image pixels corresponding to solid areas of the map are ignored.
Figure 11.119. From left to right: original image, map, resulting image
Map has three strips: a solid black area, a vertical gradient area, a solid white area. One can see, on the resulting image, that image zones corresponding to solid areas of the map, are not blurred. Only the image zone corresponding to the gradient area of the map is blurred.
![]() |
Note |
---|---|
|
You can use two types of convolution. That's the first parameter you have to set:
With White Noise: White Noise is an acoustics name. It's a noise where all frequencies have the same amplitude. Here, this option is used to create patterns.
With Source Image: The source image will be blurred.
That's the map for blur or pattern direction. This map must have the same dimensions as the original image. It must be preferably a grayscale image. It must be present on your screen when you call filter so that you can choose it in the drop-list.
Figure 11.121. Blurring with vertical gradient map
With a vertical gradient map, vertical lines are blurred.
By selecting Hue, Saturation or Brightness (=Value), filter will use this channel to treat image
The “Derivative” option reverses “Gradient ” direction:
When applying blur, this option controls how important blur is. When creating a texture, it controls how rough texture is: low values result in smooth surface; high values in rough surface.
This options controls the amount and size of White Noise. Low values produce finely grained surfaces. High values produce coarse-grained textures.
This options controls the influence of gradient map on texture.
Both values determine a range controling texture contrast: shrinked range results in high contrast and enlarged range results in low contrast.