"LIC"?

Cabral, Brian, et al. "Imaging vector fields using line integral convolution" PROCEEDINGS OF THE ACM SIGGRAPH '93 CONFERENCE ON COMPUTER GRAPHICS. Held: Anaheim, CA, USA, Aug. 1-6, 1993. Proc ACM SIGGRAPH 93 Conf Comput Graphics 1993. Publ by ACM, New York, NY, USA. p 263-270.

Painting with LIC

1. Start with a picture
2. Make a copy of the intensity of the image (ie a grayscale version)
3. Strongly blur the intensity (~20 pixel gaussian works pretty well).
4. Take the gradient of the blurred intensity, this produces a vector field whose field lines point away from bright spots.
5. Rotate the vectors in the vector field 90 degrees. Now the field lines swirl around bright spots.
6. Apply LIC on the original (color) image using the rotated vector field.
7. Make a copy of the intensity of the result.
8. Do a "gradient shade" of this intensity (i.e. do a directional derivative).
9. Multiply this result by the original result of the LIC.
10. Adjust brightness and contrast to taste.

Comments

How I do this in Photoshop:

Step 4:

Make two copies of the blurred image, and filter them with the following kernels (using the "Custom" filter):

• the derivative in the x-direction (apply to one of the images):

   1  0 -1           
   2  0 -2   or   1 -1
   1  0 -1
  

• the derivative in the y-direction (apply to the other image):

   1  2  1
   0  0  0   or   1
  -1 -2 -1       -1
  

• Note: many different kernels will work, these are just the first ones I tried.

Step 5:

Invert either the x-derivative or the y-derivative image, and then swap the x- and y- derivative images.

Step 6:

I wrote a program to do this step (I write out the original image and the gradient images, then run my LIC program, which generates the resulting image), I don't know if a LIC plug-in exists for Photoshop, it would be nice if one did...

Step 8:

Apply the following kernel:

 1  0  
 0 -1

Step 9:

Often, I change the brightness of the gradient-shade image (before the multiplication) so that it doesn't get very dark, otherwise the result of the multiplication can be too dark to fix.