I should have the programming manual for the LDP-1450 today.
Meanwhile, I've done some pretty detailed captures:
So the imaginary grid is 27 characters across, and each character is 16 pixels wide (internally), then that means the internal horizontal grid is 27*16 (432) pixels wide. Plus we have some black areas on the left and right to account for. Assuming my measurement of the blue background being 712 pixels wide is correct within 1 pixel, that means it accounts for 712/720 or 98.8888% of the horizontal space. So if we take 432/.9888 we get 436.85 pixels across as a "native" resolution to render at (I earlier calculated this number at 441 so I am now revising my earlier calculation). That means we could choose 436 or 437 pixels since we can't use fractional numbers.
Just to double check my calculations, I am going to try arrive at this same conclusion via a different path.
If 20 characters are 526 pixels wide, that means 1 character is 26.3 pixels wide. And if each character is 16 pixels wide internally, that means that the scaling rate is 26.3/16 (1.64375). Taking the total screen resolution (720) and dividing by 1.64375 gives us 438.02 as the native resolution to render at. This is a bit off from my above calculation. So what if we say that 20 characters are actually 527 pixels wide; then each character becomes 26.35 pixels wide which means the scaling is 1.646875 and the native resolution is 437.2 which is closer to what we arrived at above.
I know that I am close. The native resolution I should render at is somewhere between 436-438. All I need to do now is write some code to actually do the rendering and then play around with adjusting this value until I find something close to what I am getting with my captures.