Scanlines scaling filter in GTK Snes9x port

This is for people involved in the developement of Snes9x, or SNES emulators in general.
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mark_k
Snes9x White Belt
Posts: 8
Joined: Sun Mar 23, 2014 12:51 pm

Scanlines scaling filter in GTK Snes9x port

Post by mark_k » Mon Mar 31, 2014 4:49 pm

I've been experimenting with the scanlines scaling filter in the Snes 9x GTK port (on Linux). It's pretty strange and I'm wondering what the advantage of it is supposed to be.

In the Windows port there's a simple scanlines output mode which just makes every other row black. That's nice and can give a TV-like effect, at the expense of the brightness being reduced by half.

I assume the GTK port scanlines filter is intended to work around the reduced-brightness issue. However makes colours look washed-out and can cause strange graphical artifacts. In particular, white areas don't have any visible scanlines because the GTK scanlines code makes the intermediate lines white also.

Would there be any interest in my modifying the current scanlines filter to be simpler, like the Windows one except with variable intermediate line brightness? (You could have intermediate lines at 50% brightness so as not to reduce the overall brightness as much.)
Attachments
SMAllStars_Scanlines25_pngout.png
Super Mario All-Stars, scanlines 25%
SMAllStars_Scanlines25_pngout.png (51.19 KiB) Viewed 16367 times
SMAllStars_Scanlines100_pngout.png
Super Mario All-Stars, scanlines 100%
SMAllStars_Scanlines100_pngout.png (38.48 KiB) Viewed 16367 times
SMAllStars_NoScanlines_pngout.png
Super Mario All-Stars, no scanlines
SMAllStars_NoScanlines_pngout.png (29.39 KiB) Viewed 16367 times

mark_k
Snes9x White Belt
Posts: 8
Joined: Sun Mar 23, 2014 12:51 pm

Re: Scanlines scaling filter in GTK Snes9x port

Post by mark_k » Mon Mar 31, 2014 4:51 pm

Notice the artifacts with 100% scanlines vs no scanline effect. See the top of the larger BITMAP BROTHERS text.
Attachments
GodsBitmapBrosScanlines100.png
Bitmap Bros logo with 100% scanlines
GodsBitmapBrosScanlines100.png (14.32 KiB) Viewed 16366 times
GodsBitmapBrosNoScanlines.png
Bitmap Bros logo with no scanlines
GodsBitmapBrosNoScanlines.png (12.84 KiB) Viewed 16366 times

WalMartCartPusher
Snes9x White Belt
Posts: 32
Joined: Thu May 02, 2013 2:33 pm

Re: Scanlines scaling filter in GTK Snes9x port

Post by WalMartCartPusher » Sat Apr 05, 2014 2:13 am

This can be done with using multiple shader passes in Windows as well ;-)

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