Scratchboard: tone control

This one might use different greyness for display.
Similar to hatching by using density of lines to show tone change

Thicken the line
Morefewer

Not good from shortest to longest.

Using gradient map to draw strokes

Using 4900 strokes.

Tests for different orders

Problem 3: tested. Different orders bring different effects.

Random
Random
Random

From longest to shortest is listed below. Better?

Next steps to think about

1. Solve problems from stroke-based NPR? Worth? or not?

2. To try to apply it to mosaic. It seems very interesting now.

3. Scratchboard effects seem working, but there are some big issues. How to obtain big regions without loosing the details? And a perception question: How to represent tone and structure in lines with only black and white.

Stroke-based NPR

Applications for stroke-based NPR. The first column is using very few number of streamlines to draw the image(around 2200). And the second column is using a lot of streamlines (over 40000) to draw the image.

Problems I can see from the applications:

1. Quality of ETF. Might be made up by post drawing. E.g. losing sharp corners.

2. Shape, thickness, and the length of each stroke are not easy to choose. When is good for visualization?

3. The order of the streamlines? Based on Hertzman? From the longest to the shortest?(to be tested)

4. The color choice of each stroke? Constant colors and variant colors and textured strokes.

5. How to enhance stroke-based NPR based on current choices such as:color, directional, structure?(Some choices to be proposed and should be balanced between ...).

6. Previous ETF papers mentioned the differences between their methods and LIC. I am not sure if it's a drawback for ours.

7. How far the local controls can go? What's the goal of our styles?

Advantages:

1. A way to abstract an image

2. Directional and spatial advantage

3. Local adjustment

4. Speed??

5. Automatic

6. A new way for placement of strokes

Problems: ETF field did smooth the corners.

Another problem is that uniform regions or ramp image is not good to represent with ETF.

First try for scratchboard

It looks promising now. Next step should be focused on playing with error.

Abstract from patterns

Picasso

Scratchboard examples....