While producing some flow visualizations lately, I’ve found that smoothing a random texture gives less pixellated looking result than using a purely random texture. I added a TEXTURE keyword a while ago so that a common texture could be used for several LIC images, but now I’ve discovered that playing around with the texture a bit can be useful. I’ve been creating the texture with:

Random vs. smooth texture

IDL> r = randomu(seed, xsize, ysize)
IDL> t = bytscl(smooth(r, 3, /edge_truncate))

Click on the thumbnail image to see the full image.