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  • Joined: 06 Aug 2021
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Creating graphics for display on a CRT
Post Posted: Tue Oct 12, 2021 1:49 pm
I'm sure most of you know this but when the SMS is displayed on a CRT, the 256x192 pixels (in NTSC) get stretched a bit to fit the 4:3 CRT display. This results in pixels that are 8:7 rather than 1:1.

So my question is, when designing graphics today, how can you account for this? For example, if I want to make a perfect circle, I'll need to take this distortion into account.

Right now I'm using aseprite, and I've edited some files to allow me to use 8:7 pixels, but they get distorted when I zoom out too far, which I have to do if I'm working on an entire screens worth of pixel art. This pretty much makes it useless for creating anything other than small character sprites. Any suggestions on other software that might work better so I can better see how the graphics will look when played on real hardware on a CRT?

I'm not above getting a CRT to do pixel art drawing on if that's going to be the easiest solution, I'm just not sure how well it will play with my modern day computers. I want to be able to edit my 8:7 image in real time without the awful distortion I'm getting with aseprite.
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Post Posted: Tue Oct 12, 2021 2:14 pm
Well, to get the true effect requires either emulating the video signal quite carefully to also introduce things like encoding artefacts and blurring, or actually using that data to feed a real CRT, ideally through a real console - which is far from simple.

As a stop gap I was wondering about using a screen capture tool like OBS with filters applied to get the desired effect. This requires some level of filtering and scaling to enable 1:1 pixels to be scaled to 8:7 ratio without losing information.
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Post Posted: Tue Oct 12, 2021 2:19 pm
If you own any CRT monitors and don't want to faff about with scaling solutions for an LCD, you could always work in a screen resolution that would have a proper (or close enough) pixel aspect ratio applied without issues. Such as, for example, 768x720.

Assuming your GPU tools let you do this, or you're comfortable with using a utility such as CRU.
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Post Posted: Tue Oct 12, 2021 2:42 pm
Maxim wrote

As a stop gap I was wondering about using a screen capture tool like OBS with filters applied to get the desired effect. This requires some level of filtering and scaling to enable 1:1 pixels to be scaled to 8:7 ratio without losing information.


That's a pretty good idea. I'd probably need to use two monitors (which is fine, I have that set up) it just might be a little clunky. I'll definitely look into it though
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Post Posted: Tue Oct 12, 2021 2:46 pm
Flygon wrote

Assuming your GPU tools let you do this, or you're comfortable with using a utility such as CRU.


It doesn't let me do it, but I'm always down to learn how to use new software! I'll play around with CRU and see if I can get it working before going out for a CRT. I'm thinking about one on the smaller side just so I can fit it on my desk. It only needs to be a reference for drawing, not high action gameplay
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Post Posted: Tue Oct 12, 2021 5:24 pm
If you plan on getting a second screen, this could be interesting for you as well
CRTEmudriver
https://geedorah.com/eiusdemmodi/forum/viewtopic.php?id=295

It's what I use to make my GPU spit out 15KHz resolutions to my PVM.
Working in the various different pixel aspect ratios becomes pretty much trivial if you can send the intended res straight to your screen.
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Post Posted: Wed Oct 13, 2021 6:41 pm
Use 6:5 instead of 8:7, it'll make your life easier. In Photoshop it's also trivial, I just set the Pixel Aspect Ratio to 1.2 and bam.

Why 1.2 instead of the 1.14ish 8:7 produces? Well.

There are 3 PARs for the 8-bit games.

NTSC (8:7//1.14ish)
PAL (18:13//1.38ish)
GG (6:5//1.2)

Since most games had art shared between GG and SMS most of the PAR corrections are made with 1.2 in mind. It also happens to be a good in-between of NTSC and PAL.
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