Center-Surround Filtering

BC: CS092 / PS392 / FA294

Katherine Waters, 20 Oct 2007

For each of the 5 small images below, you are asked to:

  1. Calculate the center-surround filtering results.
  2. Render a drawing of the filtering results.
  3. Describe the filtering results.

Image in Numbers Visual Filtering Drawing Naming
9 9 9 9 9 9 9 9 9 9
9 9 9 9 9 9 9 9 9 9
9 9 0 0 0 0 0 9 9 9
9 9 0 0 0 0 0 9 9 9
9 9 0 0 0 0 0 9 9 9
9 9 0 0 0 0 0 9 9 9
9 9 0 0 0 0 0 9 9 9
9 9 9 9 9 9 9 9 9 9
9 9 9 9 9 9 9 9 9 9
9 9 9 9 9 9 9 9 9 9
This is one small, solid gray 3X3 box, surrounded by a border that is slightly darker, with significantly darker corners. Then, there is another border, with darker corners again, and another slightly darker border along the bottom and right side.
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 5 5 5 5 5 0 0 0
0 0 5 5 5 5 5 0 0 0
0 0 5 5 5 5 5 0 0 0
0 0 5 5 5 5 5 0 0 0
0 0 5 5 5 5 5 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
There is a solid gray 3x3 box near the center, surrounded by a light border, with even lighter corners. Around that border, it gets slightly darker, and then has a little bit lighter strip along the bottom and right side.
0 1 2 3 4 5 6 7 8 9
0 1 2 3 4 5 6 7 8 9
0 1 3 3 3 3 3 7 8 9
0 1 3 3 3 3 3 7 8 9
0 1 3 3 3 3 3 7 8 9
0 1 3 3 3 3 3 7 8 9
0 1 3 3 3 3 3 7 8 9
0 1 2 3 4 5 6 7 8 9
0 1 2 3 4 5 6 7 8 9
0 1 2 3 4 5 6 7 8 9
This image again has a 3x3 gray square near the center. It is bordered by a dark black strip on the right side, that slowly fades in color from right to the left, getting lighter as it proceeds left. Then, the far right and bottom edges are a solid gray just like images 1 and 2. In between these, exists various shades of gray, in a pattern that is not completely symmetrical.
5 5 5 5 5 5 5 5 5 5
5 5 5 5 5 5 5 5 5 5
5 5 4 6 8 5 9 5 5 5
5 5 1 7 0 2 7 5 5 5
5 5 9 2 9 4 0 5 5 5
5 5 9 1 7 6 2 5 5 5
5 5 4 2 4 6 3 5 5 5
5 5 5 5 5 5 5 5 5 5
5 5 5 5 5 5 5 5 5 5
5 5 5 5 5 5 5 5 5 5
This image has a border along the far right side and bottom that is solid gray and continuos. In between, there are a few dark black squares that appear to be placed haphazardly, around other squares that are very light. There is no apparent pattern that appears.
1 1 1 1 1 1 2 1 0 0 0 0 2 2 1 0 0 0 0 2
1 1 1 1 1 1 2 1 0 0 0 1 4 7 5 2 0 0 1 2
2 2 1 1 2 1 1 1 0 0 0 1 4 7 5 2 0 0 1 2
2 4 5 4 3 1 1 1 0 0 0 0 1 3 2 0 0 0 1 2
3 6 7 7 3 1 1 1 0 0 0 0 0 0 0 0 0 0 1 2
2 4 5 5 2 1 1 0 0 2 5 2 0 1 3 2 1 1 4 6
2 1 2 2 2 2 1 0 0 3 9 7 2 7 9 8 7 3 4 6
1 1 1 1 1 2 1 0 1 3 8 8 8 9 6 3 1 1 4 7
2 1 1 2 2 2 0 2 7 8 8 8 8 3 0 0 0 2 3 4
1 1 1 1 2 1 2 8 7 3 6 7 5 0 0 0 1 2 2 2
1 1 1 1 1 1 6 9 2 1 4 4 4 0 0 0 1 2 2 2
1 1 2 2 1 2 8 5 0 2 4 3 5 0 0 0 1 2 2 2
1 1 4 3 2 2 8 1 0 1 6 5 6 0 0 0 1 2 2 2
1 2 5 6 4 2 6 0 0 0 6 9 5 0 0 1 2 2 2 2
1 2 6 7 4 1 3 0 0 0 4 9 2 0 0 1 2 2 2 2
1 2 4 3 1 1 1 0 0 0 4 8 1 0 0 1 2 2 2 2
1 1 1 1 1 0 0 0 0 1 8 8 1 0 0 1 2 2 2 2
1 1 1 1 1 0 0 0 0 6 9 9 3 0 0 1 2 2 2 2
1 1 1 1 1 0 0 0 4 9 8 8 7 1 1 2 2 2 2 2
1 1 1 1 1 0 0 1 8 9 6 7 9 3 1 2 2 2 2 2
1 1 1 1 1 0 0 5 9 9 3 6 9 4 1 2 1 2 2 2
1 1 1 1 1 0 1 7 9 6 0 7 9 4 1 2 3 2 2 2
1 1 1 1 1 0 1 8 8 1 0 7 9 3 2 6 7 3 1 2
1 1 1 1 1 0 2 8 4 0 1 8 7 1 2 5 5 2 2 2
1 1 1 1 0 0 2 7 1 0 3 9 3 1 2 2 1 2 2 2
3 2 2 1 0 0 3 2 0 0 6 7 1 1 1 1 2 2 2 2
6 5 2 1 0 0 1 0 0 0 4 2 1 2 2 2 2 2 2 2
6 2 1 1 0 0 0 0 0 0 0 0 1 2 2 2 2 2 2 2
Top Left 10X10 This drawing, the upper left hand corner of the larger image. It appears to be a random pattern of light and dark spaces, that together form no distinguishable pattern with any symmetry or any object recognition.