ubb-vga: a first experiment with dithering

Werner Almesberger werner at almesberger.net
Sat May 7 23:03:24 EDT 2011

By the way, I did a dithering test: I took this image


scaled and cropped it with Gimp to 1024x768, and then dithered it with

ppmdither -red 2 -green 2 -blue 2 bouquet.ppm | ppmtojpeg | jpegtopnm >b.ppm

(the conversion to JPEG and back to PPM is to restore the color
depth to 256, which is the only one my PPM reader supports)

This is the result:


There is a bit more noise than there should be. Somehow this image
upsets some of the synchronization in the the monitor, causing those
white stripes. Ah well, another case of research showing that more
research is needed ;-)

- Werner

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