I decided to experiment with creating my own test patterns to check the linearity of my Calida 5072. I created a black and white bitmap in MS Paint with 5 equally distributed lines. I used an odd number of lines so that I can get the 5 lines equally spaced. Since I play so many 224 lines games, I created a 225 line mode to use for testing:
|225 line linearity test screen|
I got thinking... there had to be a way of getting this accurate. Here's the solution I came up with:
|Paper mask with equidistant marker lines|
|Close-up of the mask|
After that, I loaded up regular cross hatch and adjusted the horizontal size and centring. Next, I fiddled with the EW and Trap controls. The resulting grid wasn't perfect but it was extremely close for a CRT!
The benefit of all this fiddling is how good the games now look, especially when you have a vertical scroll effect. So even and smooth now!