The Line Integral Convolution (LIC) is an algorithm used to image a vector field. Its main advantage is to show in intricate detail the fine structure of the vector field. It does not display the direction or magnitude of the vectors, although this information can be color coded in a postprocessing step.

Assume we have a texture F and vector components v_x and v_y. The LIC algorithm is a mapping of F to F' that blurs F along the direction of the vector. It works by computing a local streamline for each pixel in F. Imagine that we place a particle at position (i,j) in the vector field, the streamline is the successive location of this particle forward and backward in time. The corresponding pixel in F' is given by the convolution of the texture along the streamline with a user defined kernel.

The result of course depends on the shape of the kernel and the length of the streamline. If it is too small, the texture is not sufficiently filtered and the motion is not clear. If it is too large, the image is smoothed and details of the motion are lost. For an image of size (256, 256), a value of 20 provides acceptable results.

Cabral, Brian and Laeith Leedom. Imaging vector fields using line integral convolution. SIGGRAPH '93: Proceedings of the 20th annual conference on Computer graphics and interactive techniques, pages 263-270, 1993.