LETS TALK CRTS: Barrel Distortion
So I think most people know I hate shaders on emulators. I find artificial scanlines distracting and blurring and NTSC effects to uglify things… But I get why some people like them for sure and there is an argument to be had over whats more authentic. But there is one shader I hate with a burning passion and that’s BARREL DISTORTION.
See that bowing? Yeah that. I hate it so much. Sometimes a little barrel distortion can be alright, but when it’s pumped up it just looks like hell to me. Now personal preferences are personal preferences, but seeing a lot more indie games emulate this effect, I was caught thinking “I don’t REMEMBER barrel distortion when playing on old TVs.” Which is also crazy because that’d be for me within the last 5 years. So then I see this…
Fight’n Rage looks awesome so I’m not shitting on it. Judging by older screenshots, the extreme distortion is a stylistic choice not an attempt at realism… but seeing UIs like that in emulator screenshots had me thinking “Is this right? I don’t think this is right. I think I know why this isn’t right so let me check some photos… Okay yeah this isn’t right.”
So while this is fine to do for stylistic or taste reasons, I just want to make it perfectly clear: This is not an accurate depiction of a CRT’s curved screen. Not this or the previous screenshot. Unless your goal is to emulate a busted CRT. Because apparently a think a lot of people don’t know is…
CRT’s don’t project a rectangle onto a curved surface
So lets learn about CRTs! The easiest way to know about this is by owning a flat screen CRT (I’ve owned several) and realizing ‘wait, my screen as distortion and lensing issues) and then having to go through the settings and fix it. You’d THINK displaying a rectangle on another rectangle would be easy, but CRTs don’t just project rectangles. They project all kinds of shapes and you gotta smash it into a rectangle with MAGNETS. The purpose of all this? Well no one wants their TV to look like a bubble. So the image on most CRT’s is pinched and distorted so that optically everything looks straight.
Look at this old curvy boy. You can see some lensing on it but i’s mostly pretty straight! How Well, the image – or more so, the path of the electron beam is bent by electro magnets to be…. something like
Probably not that extreme but you could get the idea. You’re counteracting one distortion with the opposite distortion.
Here is a CRT with that dialed in too far.
Wide screen HD CRTs are tweaking nightmares. Look at all the distortion in the image trying to make whatever weird shape an electron gun wants to take into a perfect rectangle.
LOOK AT THIS GOOD BOY. So straight and true. You’ll have a little distortion still but VERY VERY LITTLE.
Even at an angle you can look at the lines on this game and they look -super straight-.
If you wanna have some idea what the settings on a CRT do to the shape of the final image, watch this from 2:30
Look how fluid the image is distorted and pressed into shape. CRTs are a craaaazy technology and people did whatever they could to get a good image, even if that involved sticking in more magnets. But even basic pinch settings are interesting to watch be dialed in.
So yeah, the gestalt memory of CRT screens is like, extra crapified from what they actually looked like and it makes me sad. :(