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Why does Super Mario Bros. have so much "dot crawl"?


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I've always noticed the dot crawl (if that's what it actually is) in Super Mario Bros., and just thought it was the NES hardware's fault. What I didn't notice until recently is that other NES games don't have it, including the SMB sequels:

 

SMB:

 

jMNb1Cw.jpg

 

SMB 2:

 

P7vMIbB.jpg

 

SMB 3:

 

w6pBPDt.jpg

 

The dot crawl in SMB is even more noticeable when Mario is running and everything is moving. You don't see it when the background is black though.

 

I checked several other games and those don't have noticeable dot crawl either.

 

Does anyone know the technical reason for this?

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I would guess that the black outline around Mario is more than just an aesthetic choice -- it sharpens up the character on blurry CRT screens.

I had to look up what "dot crawl" is.
https://en.m.wikipedia.org/wiki/Dot_crawl

That effect never bothered me, but then again it has been decades since I would have had the opportunity to play these games on nasty screens without a comb filter.

Here's some advice on drawing nice-looking sprites
http://www.supermariobrosx.org/forums/viewtopic.php?t=10581

And an excerpt from a book that addresses SMB specifically.
https://books.google.com/books?id=6isWHHPii84C&pg=PT170&lpg=PT170&dq=mario+black+outline&source=bl&ots=TmIMeYDxNf&sig=VjI_ZAt-JdfnGHHeLUkQ0veTVaU&hl=en&sa=X&ved=0ahUKEwj0gozc86vQAhVHwGMKHcyEBBE4ChDoAQgdMAI#v=onepage&q=mario%20black%20outline&f=false

Short answer: SMB1 was designed as a flat, unshaded thing, which doesn't work well with the screen technology of the day. I think it looks nicer on a crisp HD screen as a result.

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To complete :

Color composite video is made by superposing the luma (black and white) signal and the color (chroma) video.

There are two issues with composite : first, the "resolution" of the chroma signal is noticeably inferior to the luma signal.

So while your luma signal is approximatively "full screen", the color signal is barely half of it. So when you stretch that signal over the luma signal, it "bleeds" because the chroma can't be as sharp as the luma signal.

Secondly, on RF, the chroma signal is "blended" into the luma signal :

 

1280px-Pal_channel.svg.png

 

Composite remove the signal carriers needed for the RF transmission but the picture is still mixed. It is why S-Video looks much sharper, because the chroma signal is no blended into the luma signal.

So, if you do not outline your graphics, like lots of older NEs games do, the edges colors will blend. with a black outline, the colors bleed but into the black part, where you can't see the bleeding, making the games looks sharper.

Edited by CatPix
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it isn't dot crawl but composite bleeding.

Color composite video is made by superposing the luma (black and white) singla and the color (chroma) video.

There are two issues with composite : first, the "resolution" of the chroma signal is noticeably inferior to the luma signal.

So while your luma signal is approximatively "full screen", the color signal is barely half of it. So when you stretch that signal over the luma signal, it "bleeds" because the chroma can't be as sharp as the luma signal.

Secondly, on RF, the chroma signal is "blended" into the luma signal :

 

Composite remove the signal carriers needed for the RF transmission but the picture is still mixed. It is why S-Video looks much sharper, because the chroma signal is no blended into the luma signal.

So, if you do not outline your graphics, like lots of older NEs games do, the edges colors will blend. with a black outline, the colors bleed but into the black part, where you can't see the bleeding, making the games looks sharper.

 

Interesting, though the SMB 2 Mario sprite doesn't have a black outline. It is outlined, but in blue:

 

EUXIg9L.png

 

Since blue is part of the chroma signal, why isn't bleeding like with the SMB Mario sprite?

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Interesting, though the SMB 2 Mario sprite doesn't have a black outline. It is outlined, but in blue:

 

EUXIg9L.png

 

Since blue is part of the chroma signal, why isn't bleeding like with the SMB Mario sprite?

 

 

My guess is that it does bleed, but you don't notice it because of the blue background helping to blend it in. Additionally black backgrounds on those levels that have it would fade the bleeding as well.

 

See...there is much more to pixel art than just making it look like something recognizable?!

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"Dot crawl" is where pixels move around as the screen moves. You can't see it in a still image. It's very noticeable in many NES games and you might think that there is something wrong with the hardware if you're not used to it. A glaring example is a minute into this Life Force playthrough.

 

https://www.youtube.com/watch?v=dt-pMJiQTTk;t=1m

Edited by mbd30
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