Line Skipping for Scanline Effect on Real DOS PC? \ VOGONS

Line Skipping for Scanline Effect on Real DOS PC?

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First post, by Titan91

Posted on 2017-12-03, 19:45

Titan91 Offline

Rank Newbie

Rank: Newbie
Posts: 8
Joined: 2017-11-19, 22:51

I have several DOS games that run in VGA mode but the spacial resolution is less, more like 320x200. My AGP card scales this up to 640x480. I am using a real CRT monitor but was wondering if it's possible to skip every other line in software so each physically drawn scanline on the screen corresponds to its own line of pixels from the game, instead of being line doubled. I have done this with photoshopped screenshots opened within Windows at 640x480:

http://i.imgur.com/ibtIST9.jpg
http://i.imgur.com/xhM1Okk.jpg
http://i.imgur.com/s1w8hwX.jpg
http://i.imgur.com/rYPDRcK.jpg

Reply 1 of 2, by leileilol

Posted on 2017-12-03, 23:47

leileilol Offline

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Posts: 11763
Joined: 2006-12-16, 18:03

Some old emulators for DOS (Zsnes, Nesticle, Loopynes) have special video modes to evoke natural scanlines (and I don't mean just dropping black on every other line in a simulated 640x480)

Though on many old monitors these modes would appear simply squished. The VGA standard typically calls for <350 line modes to be doublescanned

long live PCem

Reply 2 of 2, by jxhicks

Posted on 2017-12-05, 19:57

jxhicks Offline

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Rank: Newbie
Posts: 43
Joined: 2013-11-06, 16:09
Location: Arkansas, USA

You could use a scanline generator much like this https://www.focusattack.com/scan-dl-vga-scanline-generator/. It should give you the effect you are looking for, though it is also going to reduce the overall brightness of the screen quite a bit.

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