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Special features

Beyond authentically emulating real CRT monitors, DOSBox Staging offers two visual enhancements that are impossible on real hardware: blending away dither patterns in old EGA and CGA games, and deinterlacing FMV videos to remove the distracting black lines found in many 90s games.

Both are opt-in and work best when enabled per-game rather than globally.

FMV deinterlacer

Many 90s DOS games displayed full-motion video (FMV) using interlaced rendering, showing only every second line of each frame. This halved storage requirements and looked fine on small CRTs where the brain filled in the gaps, but on modern flat screens the alternating black lines look distracting and halve the apparent brightness.

The deinterlacing setting automatically detects interlaced regions within each frame and reconstructs the missing lines. The detection is intelligent; it only touches interlaced areas while leaving HUDs, UI frames, subtitles, and mouse cursors untouched.

Both common interlacing patterns are supported: standard line interlacing (alternating black horizontal lines, used by most games) and “dot interlacing” — a special pattern used by the CD-ROM versions of Dune and KGB.

Note

Enabling vertical integer_scaling is recommended on lower resolution displays to avoid interference artifacts when using lower deinterlacing strengths. Alternatively, use full strength to completely eliminate all potential interference patterns.

Games that benefit from deinterlacing

Here’s a non-exclusive list of DOS games that benefit from the deinterlacing feature:

Checkerboard dedithering

Many DOS games used dithering — alternating pixel patterns — to simulate more colours than their limited palette could display. This was especially common in 16-colour EGA games, where checkerboard patterns created the illusion of intermediate shades.

The dedithering setting detects these checkerboard patterns and blends them into solid colours. It works with any graphics adapter (CGA, EGA, VGA, Hercules) and any resolution, and can be combined with any shader.

Note

Dedithering is not a more authentic representation. On real PC CRT monitors, dither patterns were clearly visible. Blending them into solid colours was only a thing on consoles connected to consumer TV sets. For a more authentic look, use shader = crt-auto instead.

Games that benefit from dedithering

Here’s a non-exclusive list of DOS games that benefit from the dedithering feature:

Configuration settings

You can set these in the [render] configuration section.

deinterlacing

Remove black lines from interlaced videos. Use with games that display video content with alternating black lines.

Possible values:

  • off default – Disable deinterlacing.

  • on – Enable deinterlacing at medium strength.

  • light – Black scanlines are softened to mimic the CRT look.

  • medium – Best balance between removing black lines, increasing brightness, and keeping the higher resolution look.

  • strong – Image brightness is almost completely restored at the expense of diminishing the higher resolution look.

  • full – Completely removes black lines and maximises brightness, but the image will appear blockier.

Note

Enabling vertical integer_scaling is recommended on lower resolution displays to avoid interference artifacts when using lower deinterlacing strengths. Alternatively, use full strength to completely eliminate all potential interference patterns.

dedithering

Remove checkerboard dither patterns from the video output. Useful with CGA and EGA games that use dither patterns to create the illusion of more colours.

Possible values:

  • off default – Disable dedithering.

  • on – Enable dedithering at full strength.

  • <number> – Set dedithering strength from 0 (off) to 100 (full strength). Lower values softly blend dither patterns; higher values blend between the original and the fully dedithered image.

Note

  • Dedithering only works in OpenGL output mode.

  • Dedithering is applied to rendered screenshots, but not to raw and upscaled screenshots and video captures.