Ugly lines from the ETF and the gradients

Based on the ETF
Based on gradients

The first heightening effects based on pixels not lines

Experiences: Whitening for the highlights is only enhancement for effects. The key information still depends on the good shading.

Some watercolor-like effects when creating heightening

Choose different diffusion for different areas

The next step is to control the initial condition and the boundary condition and to use different functions or different diffusion to model the surface.

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How to deal with narrow areas?

The original image
3000 iterations, 120 seconds
2000 iterations
After 500 iterations(32 seconds), pixels with height values between 0.1 to 0.000001 are shown in red. It means the narrow areas around the hair have a lot almost-zero heights.
500 iterations
100 iterations

A better result

Not good for small regions.

Heightening with white lines on brown paper

The original image

Darker pixels are from ETF and white lines are drawn manually to show the effects. It seems the quality of white lines play an important role to show the constrast.

(Heightening: the term used for highlights applied to a drawing with white chalk or white/tinted bodycolour.)

Better long streamline

One way to make the short streamline longer

When tracing the ETF, if it stops at some pixel and let it find which pixel is valid as replacement. It gets some jagged long streamline. After poping it up by dilation, it has kind of smoothing. But it is still messy!