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(6.5,4.5, error =error+ 20)
(6.5,4.5, error = error)

Final results---Scaling the errors based on the stipple size

Around 10000 stipples
Around 20000 stipples
Around 15000 stipples

Looks better in vector way than in pixel way.

Around 20000 stipples
It did give control over the number of stipples, but it also ruins the structure.

Other results and effects

Good result from combining ETF and our halftoning

In EGSR, 2008, by Kim et al.

Our result

Other testing for textures

Not always good

Find a way to gradually transit between 127 and 129 based on different dot sizes

129
127
grayness = 129(49055 black dots size 1)grayness = 127(43501 white dots, size 1)

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grayness = 129(49055 black dots, size 2)
grayness = 127(43501 white dots, size 2)

Black on white and white on black

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Choose same dots as follows, but use the dot size 2 to draw it.
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Based on the original image
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It improve the quality of black, but the inbetween tones are ruined.
Lena(around 10000 black dots and 11000 white dots)
Based on the scaled image

Some placement for patterns

Might be useful for packing in image space

Manage the order

Only showing the first level and the third level.
This image is obtained by first choose edges as first level. At the first level, only control the density. The next level is dark area, which is not well-represented now. The last level is the light area.

First level based on sobel

master most of structure but it uses 28000 dots.

Put white dots on black background when it is an uniform dark area

around 40000 black dots and around 36000 white dots

This demo uses over 54000 black dots(saving 20000 dots) and around 3000 white dots.
Put white dots on chosen uniform dark area. It did work better for showing dark area. But the library for showing vector graphics I chosen only supports changing the whole background color not partially. So there might be a problem for showing vector graphics.

The white uniform area shows where the modified area is.

To represent structures with small dots and uniform region with big dots

Problems with vector graphics and image: have different visualization. How to match them?

To preserve structure by using small stipples:

(1)A map for showing deviation, lighter area has higher structure.

(2)Vary stipple sizes. If it has higher deviation, use small stipples. If it is a uniform and close to black region, use largest stipples. Others are based on the intensity.

(3)Vary stipple sizes and remove stipples if they are sticked together.

(There are some vector graphics shared on google docs with you.)

(4)Only by choosing different scaling function to adjust the density.

(There are some vector graphics shared on google docs with you.)