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Colour & image adjustments¶

The image adjustment controls — brightness, contrast, saturation, colour temperature, and more — work much like the knobs on an old CRT monitor. They’re useful for fine-tuning the picture to your taste or compensating for differences in display characteristics.

CRT colour profiles go a step further, emulating the distinct phosphor colours of different monitor types. On wide gamut displays these profiles can reproduce CRT colours that fall outside the standard sRGB colour space more accurately.

For Hercules and CGA machines, DOSBox Staging offers authentic monochrome display emulation mimicking classic amber, green, white, and paperwhite looks.

CRT colour profiles¶

Different CRT monitors used different phosphor chemistries, giving each a distinct colour character. DOSBox Staging can emulate these via the crt_color_profile setting.

  • p22 — P22 phosphors were the most common in PC monitors, producing warmer, slightly desaturated colours. This is what most people saw when playing DOS games.

  • smpte-c — SMPTE-C broadcast standard phosphors are close to P22 but with tighter colour tolerances, used in professional video monitors.

  • ebu — EBU phosphors are the European broadcast standard, found in high-end professional monitors like the Sony BVM/PVM series.

  • philips — Philips home computer monitors (e.g., the Commodore 1084S) had distinctly warm, yellowish whites at roughly 6100K.

  • trinitron — Sony Trinitron monitors were known for punchy, vivid colours with a cool blue-white colour temperature around 9300K.

The auto setting picks the profile that matches the era: CGA and EGA games get P22 (matching the monitors of that era), VGA games also get P22, composite video gets SMPTE-C, and the arcade shaders use Philips. See the Automatic image adjustments table for the full mapping.

Monochrome display emulation¶

For hercules and cga_mono machine types, the monochrome_palette setting offers four classic looks:

  • amber — The warm orange-yellow glow of monitors like the IBM 5151 with an amber phosphor. The most common monochrome display in offices and the most comfortable for extended reading.

  • green — The classic green phosphor look of the original IBM 5151 green screen, a staple of the early PC era.

  • white — A cool blue-white typical of later monochrome VGA monitors.

  • paperwhite — The Hercules-era paperwhite phosphor, a warmer, slightly yellowish white that’s easier on the eyes than pure white.

You can cycle through the available palettes via hotkeys during gameplay.

Automatic image adjustments¶

When crt_color_profile, color_temperature, or black_level are set to auto, DOSBox picks period-appropriate values for each video mode. CGA and EGA games look like they did on the slightly warm, high-colour-temperature monitors of the 1980s, while VGA games get the cooler, more neutral look of 90s PC monitors.

The selection logic depends on the shader mode:

  • crt-auto selects settings based on the graphics standard of the current video mode (CGA, EGA, VGA, etc.), irrespective of the machine setting. EGA modes that reprogram the VGA’s 18-bit DAC palette get VGA settings to reflect that they require VGA hardware.

  • crt-auto-machine selects settings based on the emulated machine type configured via the machine setting.

  • crt-auto-arcade and crt-auto-arcade-sharp always use fixed arcade monitor settings.

  • Regular shaders (e.g., sharp, bilinear) select settings based on the emulated machine type.

In all modes, composite video always uses composite-specific settings regardless of the machine type.

Video mode CRT profile Colour temp (K) Black level
Monochrome None 6500 0
Composite SMPTE-C 6500 0.53
CGA / PCjr P22 9300 0.65
EGA / Tandy P22 9300 0.60
VGA / SVGA P22 7800 0
Arcade Philips 6500 0.50

Note

The black level values shown are for DCI-P3 colour spaces with gamma 2.6 or higher. For lower-gamma colour spaces (sRGB, Display P3), the black level is halved.

Wide gamut colour accuracy¶

CRT monitors used phosphor coatings with colour gamuts that often fall outside the sRGB colour space used by most modern displays. P22, Trinitron, and Philips phosphors all have saturated primaries that sRGB cannot reproduce. A wide gamut display (DCI-P3 or wider) lets DOSBox Staging render these colours faithfully.

The practical benefit depends on your operating system:

  • macOS always outputs in the Display P3 colour space. The OS handles the conversion to your monitor’s actual colour profile automatically, giving you the most accurate results out of the box.

  • Windows and Linux currently output sRGB. A DCI-P3 monitor still helps because the Philips and Trinitron profiles push colours toward the gamut boundary, but full accuracy requires macOS or a future colour-managed rendering path on these platforms.

If you have a wide gamut display, the auto defaults for crt_color_profile and color_space give you accurate colours out of the box. The Philips and Trinitron profiles show the biggest difference on DCI-P3 versus sRGB displays.

Image adjustments¶

The image adjustment system emulates the controls of a CRT monitor. The image_adjustments setting enables or disables all adjustments. When disabled, the raw RGB values from the emulated video adapter are displayed without any processing (except colour space conversion).

The available adjustments are:

You can tweak these in real-time using hotkeys — use PrevImageAd / NextImageAdj to select a setting and DecImageAdj / IncImageAdj to adjust its value. The adjusted values are logged so you can copy them into your config. Alternatively, use the CONFIG -wc DOS command to write the current settings to a config file.

CGA palette override¶

The 16-colour CGA/EGA RGBI palette can be overridden with alternative colour interpretations via the cga_colors setting. This affects CGA/EGA-like modes even on emulated VGA or Tandy graphics adapters.

Several built-in presets are available, including Amiga and Atari ST colours for Sierra AGI games, various CGA/EGA monitor emulations, and Commodore 64 inspired colours. Custom palettes can also be specified.

The tandy-warm preset emulates colours as they appear on an actual Tandy monitor, resulting in more subdued and pleasant colours — especially apparent on the greens.

Configuration settings¶

You can set the colour parameters in the [render] configuration section.

Colour gamut¶

color_space¶

Set the colour space of the video output. Wide gamut colour spaces can reproduce CRT phosphor colours that fall outside the sRGB gamut — see Wide gamut colour accuracy for details.

On macOS, this is always display-p3; the OS performs the conversion to the colour profile set in your system settings. On Windows and Linux, the effective output is currently sRGB.

Possible values:

  • display-p3 – Display P3 wide gamut colour space with 6500K white point and sRGB gamma.

Note

Colour space transforms are applied to rendered screenshots, but not to raw and upscaled screenshots and video captures (those are always in sRGB).

Monitor emulation¶

crt_color_profile¶

Set a CRT colour profile for more authentic video output emulation.

Possible values:

  • auto default – Select an authentic colour profile appropriate for the currently active adaptive CRT shader, or the current machine type for regular shaders.

  • none – Display raw colours without any colour profile transforms. This will result in inaccurate colours and gamma on modern displays.

  • ebu – EBU standard phosphor emulation, used in high-end professional CRT monitors such as the Sony BVM/PVM series.

  • p22 – P22 phosphor emulation, most common in lower-end CRT monitors.

  • smpte-c – SMPTE “C” phosphor emulation, the standard for American broadcast video monitors.

  • philips – Philips CRT monitor colours typical to 15 kHz home computer monitors (e.g., the Commodore 1084S). Intended to be used with color_temperature set to 6500. Output looks yellowish due to the ~6100 K colour temperature baked into the profile. Needs a DCI-P3 display for the most accurate results.

  • trinitron – Typical Sony Trinitron CRT TV and monitor colours. Intended to be used with color_temperature set to 6500. Output looks blueish due to the ~9300 K colour temperature baked into the profile. Needs a DCI-P3 display for the most accurate results.

monochrome_palette¶

Set the palette for monochrome display emulation. Works only with the hercules and cga_mono machine types.

Possible values: amber default, green, white, paperwhite.

Note

You can also cycle through the available palettes via hotkeys.

Image adjustments¶

image_adjustments¶

Enable image adjustments. When disabled, the image adjustment settings have no effect and raw RGB values are used for video output. Colour space conversion is always active and cannot be disabled (see color_space).

Possible values: on default, off

Note

  • Image adjustments only work in OpenGL output mode.

  • Adjustments are applied to rendered screenshots, but not to raw and upscaled screenshots and video captures.

  • Use the PrevImageAdj and NextImageAdj hotkeys to select an image adjustment setting and the DecImageAdj and IncImageAdj hotkeys to adjust settings in real-time. Copy the new settings from the logs into your config, or write a new config with CONFIG -wc.

brightness¶
Set the brightness of the video output (45 by default). Valid range is 0 to 100. Emulates the brightness control of CRT monitors that sets the black point; higher values raise the blacks.
contrast¶
Set the contrast of the video output (65 by default). Valid range is 0 to 100. Emulates the contrast control of CRT monitors that sets the white point; higher values raise the blacks (lower brightness to compensate).
gamma¶
Set the gamma of the video output (0 by default). Valid range is -50 to 50. Additional gamma adjustment relative to the emulated monitor’s gamma.
digital_contrast¶
Set the digital contrast of the video output (0 by default). Valid range is -50 to 50. Unlike contrast, this is applied directly to the raw RGB values of the framebuffer image.
black_level¶

Raise the black level of the video output. Applied before brightness and contrast, so it acts as a black level boost.

Possible values:

  • auto default – Raise the black level for PCjr, Tandy, CGA and EGA video modes only for adaptive CRT shaders; use 0 for any other shader.

  • <number> – Set the black level raise amount. Valid range is 0 to 100. 0 does not raise the black level.

Note

Raising the black level adds visual interest to PCjr, Tandy, CGA, and EGA games by enhancing the “black scanline” emulation look.

saturation¶
Set the saturation of the video output (0 by default). Valid range is -50 to 50. Applied directly to the raw RGB values of the framebuffer image, similarly to digital_contrast.
color_temperature¶

Set the colour temperature (white point) of the video output.

Possible values:

  • auto default – Select an authentic colour temperature appropriate for the currently active adaptive CRT shader, or the current machine type for regular shaders.

  • <number> – Specify colour temperature in Kelvin (K). Valid range is 3000 to 10000. 6500 K is the neutral point for most modern displays. Values below 6500 produce warmer colours; above 6500 produce cooler colours.

color_temperature_luma_preserve¶
Preserve image luminosity prior to colour temperature adjustment (0 by default). Valid range is 0 to 100. 0 performs no luminosity preservation; 100 fully preserves it. Values greater than 0 result in inaccurate colour temperatures in brighter shades, so keep this at 0 or close to it if your monitor is bright enough.
red_gain¶
Set gain factor of the red channel (100 by default). Valid range is 0 to 200. 100 means no change.
green_gain¶
Set gain factor of the green channel (100 by default). Valid range is 0 to 200. 100 means no change.
blue_gain¶
Set gain factor of the blue channel (100 by default). Valid range is 0 to 200. 100 means no change.

Colour palette¶

cga_colors¶

Set the interpretation of CGA RGBI colours. Affects all machine types capable of displaying CGA or better graphics, including the PCjr, Tandy, and CGA/EGA modes on VGA adapters.

Built-in presets:

  • default default – The canonical CGA palette, as emulated by VGA adapters.

  • tandy <bl> – Emulation of an idealised Tandy monitor with adjustable brown level (0–red, 50–brown, 100–dark yellow; defaults to 50).

  • tandy-warm – Emulation of the actual colour output of an unknown Tandy monitor. Intended to be used with crt_color_profile = none and color_temperature = 6500.

  • ibm5153 <c> – Emulation of the actual colour output of an IBM 5153 monitor with a unique contrast control that dims non-bright colours only. The contrast can be optionally provided as a second parameter (0 to 100; defaults to 100). Intended to be used with crt_color_profile = none and color_temperature = 6500.

  • agi-amiga-v1, agi-amiga-v2, agi-amiga-v3 – Palettes used by the Amiga ports of Sierra AGI games.

  • agi-amigaish – A mix of EGA and Amiga colours used by the Sarien AGI-interpreter.

  • scumm-amiga – Palette used by the Amiga ports of LucasArts EGA games.

  • colodore – Commodore 64 inspired colours based on the Colodore palette.

  • colodore-sat – Colodore palette with 20% more saturation.

  • dga16 – A modern take on the canonical CGA palette with dialled back contrast.

You can also set custom colours by specifying 16 space- or comma-separated sRGB colour values, either as 3 or 6-digit hex codes (e.g., #f00 or #ff0000 for full red), or decimal RGB triplets (e.g., (255, 0, 255) for magenta).

Note

These colours will be further adjusted by the video output settings (see crt_color_profile, brightness, saturation, etc.)