"Dithered" output increases resolution

By switching between two values in adjacent pixels, the voltage seen at the scope is an intermediate value between the two.] For instance, to display a pixel at X=128.5, alternate between blue=128 and blue=129. This happens because the pixel clock is faster than the bandwidth of the rest of the system---in particular, this signal is at about 75MHz, while the scope has a "20MHz bandwidth limit" button.

So without complicated extra hardware, I've got a nice 512x512 output, which gives me a 64x48 character vector terminal. It's a lot more readable than this screenshot makes it appear. 768x768 (a 3-pixel ordered dither @ 50MHz) and 1024x1024 (4-pixel, 37MHz) dithered resolutions may also work. Watch this space.



Entry first conceived on 1 May 2005, 20:36 UTC, last modified on 15 January 2012, 3:46 UTC
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