For those not familiar with old IBM systems, I'll point out that the 3270 is not a specific machine, but an "Information Display System", made up of various control units, display stations, and printers. As time went on, different models in the 3270 line appeared such as the color 3279 display with 4 color text, expandable to 7 colors. So there's not the "one true 3270 display".
[1] http://www.bitsavers.org/pdf/ibm/3270/GA27-2749-1_IBM_3270_I...
I tried to remain accurate, but allowed significant deviations for accented characters, which, in the originals, had letters vertically compressed to make room for the accent.
There are also lots of glyphs that were never in a 3270 terminal.
I remember the standard setup for a 3279 color terminal was to go through and align the red, blue and green guns at a number of points on the screen. When you had aligned them all, the target dot was white. It was very common to see badly aligned displays (some were hard to align in any case) where the letters had a pinkish shadow effect form misalignment of the guns. Good times.