ChristopherJam
Registered: Aug 2004
Posts: 1408 |
Christopher Jam's composite video measurements
I spent a month or two back around the start of 2015 measuring the composite video output of a new luminance c64 using a 100MHz USB oscilloscope, then trying to reproduce the output waveform using a simple predictive model.
Before I started, I had this crazy idea that I could use the fragments of chroma signals from each pixel to manufacture new colours, on the assumption that each pixel would be a well defined slice of a sinewave. Ahahahaha. Nothing so simple. Chroma takes several pixels to start up and shut down again, and the luma signal rings visibly for four or five pixels.
I do now however have a pretty accurate model of the luma behaviour, and my chroma model is not far off.
Some pretty graphs and test images at http://jamontoads.net/p/lumachroma.html
Here's a teaser
and a palette :)
jampal=[000000, ffffff, 7d202c, 4fb3a5, 84258c, 339840, 2a1b9d, bfd04a, 7f410d, 4c2e00, b44f5c, 3c3c3c, 646464, 7ce587, 6351db, 939393] |
