how to run game in native resolution without stretch/scale

[scar]

I have Retropie 4.1 and is connected to my HDTV @ 1920 x 1080. Retropie and Emulationstation both run great in that resolution. But when I launch an old Atari game, the game is stretched to fill my whole TV and it is very blocky... I would like the game to run in a small portion of my entire HDTV so the graphics look a bit better. I have tried "Select video mode for rom" but it doesn't matter what resolution I pick, it always looks the same. how can i prevent this stretching/up scaling?
Thanks

[Lyle_JP]

You may want to look into a video shader instead to minimize the blocky look. The crt-pi shader will give those Atari 2600 games a genuine "old tube tv" appearance. Or even just video smoothing. I think both are better alternatives than playing on a postage-stamp sized screen area (which will still look blocky, just smaller).

You can use the configuration editor to enable shading or smoothing on a system by system basis.

[dankcushions]

@scar if you 'prevent' upscaling, the image will be in a small postage stamp-sized section of your screen. the native resolution of that system is approx 2% of a 1080p screeen.

[scar]

@dankcushions is there a way to upscale just a little, so its using like 25% of the screen or something?

@Lyle_JP will look into those options thanks

[edmaul69]

@scar yes crt-pi shader will give you a good authentic look.

[scar]

crt-pi does look nice but it uses too much cpu on my old Pi 1 B

[Aryetis]

Create a hotkey to modify overscan accordingly on the fly. Maybe there is even a way to use runcommand to modify overscan

[J.Beau]

Try integer scaling in the retroarch menu (select-x).