This filter renders the input frame in 2 (user selectable) colours. It uses circles whose radii depend upon the luminescence of the input block to reproduce a version of the original image.

The output of halftone doesn't resize particularly well since the circles tend to look square. So do any resizing on the video before applying the filter. Due to this, I present an full size example of the filter below.

original image halftoned

The filter can be slow on preview. However, encoding occurs at more reasonable speed since the filter does a lot of caching. I get ~3 fps for a 640x480 stream doing a divx4->divx4 encode with the filter in the middle on my Duron 933.

In order to generate the halftone effect, first the image is pixellated. The luminescence of each block is recorded and used to find the radius of the circle which is drawn inside it. The circles are finally antialiased (2x supersampled) to produce the final image.

The inspiration (Lobachevsky) for this filter was the Vandread Second Stage opening. It's not very good but it has a nice halftone effect :).

Future plans: fix higher levels of supersampling (non-selectable in this version), make nice graduated circles like in Vandread.

Download the filter and source code (zip file).

This filter is distributed under the GPL and uses code from Donald Graft's excellent Colorize filter.

Back to filter page.

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