Yesterday, I managed to linearise my CRT monitor. I was not impressed by it, things looked awkward and the gamma value was way off the normal range. When I wrote my post yesterday, I went home thinking about an ageing triode: as I said before, the characteristics shift towards lower currents (luminance!), with some pretty bad non-linear distortion. So I plotted my measured gamma values against the driving signal. Bingo. Gamma was around 4 on 6% brightness and 2.5 at 96%. Whoa.
So I had to change the bias on the valve (monitor: increase brightness to around 80% from the factory-set 50), until I could perceive a 1% patch with respect to the black background. Yes, and I re-did all 300 of my measurements as well… this time it worked as expected: gamma varies from 2.3 to 2.8. A bit too hefty on the red, but I don’t need to worry about that, as I am now interested in luminance only.
Yes, I managed to linearise the monitor with both settings. However, there are moments when ‘things work, but they don’t feel right’, and this was one like that.
I assembled my experiment setup, and tested myself to obtain preliminary data. Well, I’m not blind :). But my vision surely doesn’t know how to solve an integral!