The native resolution of the PiTFT screen works quite well for retro gaming — quite a few 1980s CRT-based arcade and home systems worked at or around this same resolution.
For certain projects though…emulating later systems, home computers with higher-resolution displays, or if you just want to run GUI-type X11 Linux applications on the PiTFT…there just aren’t enough pixels. Application windows and other elements may extend off the right or bottom edges of the screen.
The fbcp program (installed by our script on the PiTFT Setup page) has the ability to scale higher-resolution graphics down to the PiTFT’s limited size, with image interpolation so elements like text (unless extremely small) are often still quite legible at the reduced size. fbcp does all this automatically, we just need to change the HDMI output resolution, and on next boot we have a larger graphical canvas (the actual PiTFT resolution itself does not change).
Edit the file /boot/config.txt — use the “sudo” command for root access:
Look for this line, most likely near the bottom:
(On the 3.5" PiTFT, the first two numbers will be 480 and 320.)
Try doubling the values to 640 and 480 (or 960 and 640 for the 3.5" PiTFT):
Save changes to the file, then exit and reboot. When the system comes up, you’ll see everything is smaller, but antialiased and still generally legible.
You can use even higher resolution settings if needed (up to the Pi’s full HD resolution), but this 2X scale is optimal. The bilinear image interpolation algorithm may start to drop details if the HDMI resolution is more than 2X the PiTFT resolution. An exact 2X scale also maintains the same 4:3 aspect ratio as the PiTFT (3:2 for 3.5"), so the image isn’t “squashed” horizontally.