You’re setting up your retro gaming rig or dusting off your old arcade cabinet, and you connect it to a modern LED display. The image appears flat, hyper-sharp, and somehow wrong—like you’re looking at a photograph of the game rather than playing it. The colors feel oversaturated, the scanlines are invisible, and there’s a sterile quality that bears no resemblance to how you remember these games looking on actual CRT monitors.
The problem isn’t your display or your console. It’s that you’re looking at pixels rendered on a fundamentally different technology that was invented decades after your original hardware. CRT monitors used phosphor decay, electron beam scanning, and analog signal processing to create a look that became inseparable from how those games were designed and balanced.
CRT emulation—the software and hardware techniques that recreate the visual characteristics of a cathode ray tube display—has become the standard solution. But the settings involved aren’t aesthetic fluff. They’re engineering choices based on how CRT displays actually functioned physically. Understanding what each setting does, why it exists, and how to dial it in correctly transforms a flat digital image into something that looks, feels, and even plays like the original hardware.
The challenge is that CRT emulation has no single “correct” setting. Every monitor was slightly different. Every arcade cabinet had different convergence and geometry calibrations. The room lighting mattered. The signal quality mattered. And your particular combination of hardware and emulation software will require specific adjustments.
## The question: What do CRT emulation settings actually do, and how do you know which ones to use?
Most people reach for CRT shaders and monitor simulation software without understanding what they’re correcting for. You’ll find endless forum arguments about “which shader looks most authentic” without any discussion of the actual physics involved. This confusion leads to over-sharpened images, incorrect color response, or conversely, overly blurry displays that sacrifice detail for a vague sense of “retro.”
Over the next few minutes, you’ll learn exactly what a CRT display was doing electronically, how modern displays differ from them, which emulation settings map to real physical phenomena, and how to measure whether your settings are actually working correctly. By the end, you’ll have a framework for evaluating CRT emulation presets and adjusting them for your specific hardware and viewing environment—with genuine understanding, not guesswork.
## How CRT displays actually worked—the physics that emulation is trying to recreate
A cathode ray tube monitor created images through a fundamentally analog process. An electron gun at the back of the tube fired a beam of electrons toward a phosphor-coated screen at the front. Magnetic coils deflected that beam in precise patterns—left to right, top to bottom—to “paint” the image line by line. The phosphor glowed where the beam hit and faded away between refreshes.
This process had several non-trivial consequences for image appearance that modern digital displays don’t replicate.
**Scanlines and beam shape.** The electron beam wasn’t a mathematically perfect point. It had physical width (typically 0.3-0.5mm on arcade monitor tubes), and it created visible horizontal lines across the display where each pass of the beam occurred. These scanlines became part of the visual vocabulary of 8-bit and 16-bit gaming. They weren’t a defect—they were a feature of the hardware that game artists learned to work with, using them to add visual texture and break up color banding.
Modern displays are pixel-grids rendered all at once. There’s no scanning motion, no beam trail, no phosphor glow-and-fade cycle. The image appears flat by comparison.
**Convergence and geometry distortion.** Real CRT monitors had mechanical and electrical adjustments to align the red, green, and blue beams (or in single-beam designs, to position the beam correctly on the screen). These were never perfect. Most arcade cabinets and consumer monitors had slight geometric distortions—barrels, pincushion effects, or edge blur—that varied from unit to unit and degraded over time as the CRT aged.
Many people think of this as “degradation” and try to correct for it in emulation. Actually, it was part of the authentic look. A perfectly corrected CRT that never existed is less accurate than a slightly distorted one that did.
**Phosphor persistence and glow.** Phosphors didn’t stop glowing instantly when the beam moved away. They decayed gradually, creating a glow and blur effect that smoothed sharp pixel transitions. Different phosphor types had different persistence curves—some decayed in milliseconds, others held their glow for 20-30ms. This blur effect is often misremembered as “smoothing” but it was actually frequency-dependent; sharp horizontal lines (like scanlines) remained visible while fine diagonal details got blurred together.
**Aspect ratio and overscan.** CRT displays rendered slightly more image data than actually appeared on the screen—the edges were cropped off (overscan). This varied between consumer monitors, arcade cabinets, and broadcast standards. Additionally, CRT monitors didn’t have square pixels. Arcade monitors and consumer sets had different aspect ratios, and some games were designed for slightly distorted pixels intentionally.
**Signal-level characteristics.** Composite, S-video, and RGB signals fed into CRT monitors were analog and had bandwidth limitations. High-frequency detail got rolled off. The signal also had voltage headroom issues—levels that were nominally 0-255 in digital space were transmitted as 0-1.0V analog, and the relationship between input voltage and displayed brightness was nonlinear (gamma correction). This affected color saturation, black levels, and perceived contrast.
Modern flat panels receive pure digital input with perfect fidelity. Every digital level maps to an exact pixel value. There’s no bandwidth limiting, no signal loss, no gamma curve unless you explicitly apply one.
## Why this matters: The games were designed for CRT hardware
This isn’t nostalgic hand-wringing. The visual compromises and characteristics of CRT displays became part of how games were made.
Sprite artists worked knowing that diagonal lines would blur slightly. They sometimes used this to their advantage—a diagonal edge rendered across 2-3 pixels would appear smoother on a CRT than on a modern display. Palette designers chose colors and dithering patterns knowing they’d be affected by phosphor convergence and beam width. Level designers used scanlines to add texture to large solid-color areas.
When you look at those games on a modern display without proper emulation, you’re not seeing what the artist intended. You’re seeing artifacts of low resolution magnified and sharpened. The dithering patterns become obvious. The color transitions look jagged. The overall aesthetic is wrong.
Proper CRT emulation reverses this. It applies the blur, the scanlines, the phosphor glow, and the signal-level bandwidth limiting that were always supposed to be there. The result looks correct not because it’s “retro” or “warm” but because it matches the actual presentation hardware.
## The practical emulation settings and what they control
CRT emulation typically happens through one of three methods: GPU shaders (on emulators like RetroArch), dedicated hardware (FPGA boards like MiSTer), or actual CRT displays (increasingly rare but still the gold standard). We’ll focus on shader-based emulation since it’s the most accessible.
### Scanline intensity and pattern
This controls the brightness and visibility of the horizontal lines. The key parameter is usually expressed as a percentage or ratio—how much darker are the scanlines compared to the brightest parts of the image?
Real CRT scanlines were typically 30-50% of peak brightness on arcade monitors, slightly less prominent on home TV sets. A setting of 0% makes them invisible (no emulation). A setting above 60-70% looks artificial and overshadows the actual image detail.
The correct value depends on the original display type and your viewing distance. Sitting close to an arcade cabinet, scanlines are very visible. Playing an NES on a TV from across the room, they’re much more subtle. Most shader presets default to 50%, which is a reasonable compromise but not universal.
What matters is that scanlines should follow the actual horizontal lines of the game image. Poor emulation renders them as a fixed pattern on top of the image, which looks wrong when the image scrolls. Good emulation ties them to the raster scan timing.
### Phosphor simulation and bloom
This is where the actual glow and persistence of the phosphor gets emulated. A phosphor bloom shader will cause bright pixels to glow outward slightly and to influence neighboring pixels for a frame or two after they appear.
The strength of this effect should be subtle. Too much bloom, and the image becomes fuzzy and loses legibility. Too little, and you lose the characteristic softness that made curved edges readable on low-resolution displays.
A good starting point is 0.5-1.5 pixels of bloom radius with 10-30% intensity. The effect should be noticeable only at high contrast boundaries (bright pixels against dark backgrounds). Mid-tone transitions should appear smooth but not blurred.
Phosphor color also matters. Different phosphor types (P4, P22, P43, etc.) produced different color characteristics. P4 phosphors, common in arcade monitors, had slightly greenish shadows and yellowish highlights compared to modern RGB displays. This isn’t necessarily “better”—it’s just different and part of the authentic look.
### Geometric correction and curvature
Real CRT displays had curved screens (mostly), and they had nonlinear scan patterns at the edges due to how magnetic deflection works. This created barrel distortion—straight lines near the edges appeared slightly curved outward.
Modern emulation can simulate this curvature. The question is whether it should. A perfectly flat image is technically more accurate to the ideal behavior of a properly adjusted monitor, but most real monitors, especially arcade cabinets, had visible curvature.
A light barrel distortion of 1.0-1.5% (measured as maximum edge deviation relative to screen width) is a reasonable approximation. Much more than this looks cartoony. Less than this loses some of the characteristic CRT “look.”
Importantly, curvature should be based on the actual monitor type you’re emulating. A consumer TV might have 1% barrel distortion. An arcade monitor might have 2-3%. A perfectly flat vector-graphics monitor (Vectrex, Battlezone) should have no curvature at all. Don’t apply curvature universally—match it to your content source.
### Aspect ratio correction
Early arcade games and home consoles had specific intended aspect ratios. Atari 2600 was 4:3 but with slightly wide pixels. Genesis and SNES were also 4:3. Arcade cabinets varied; some were 4:3, some were wider.
The trap is applying modern square-pixel aspect ratio correction universally. A game that looks “correct” on its original hardware with slightly rectangular pixels shouldn’t be stretched to perfect squares. Instead, match the pixel aspect ratio of the original display.
For most NTSC (North American arcade and home) content, pixels were roughly 1.07:1 (slightly wide). PAL content (Europe) was roughly 1.22:1 (more elongated). MAME and RetroArch let you adjust this, but the default settings often correct to perfectly square pixels, which is actually wrong.
### Signal bandwidth limiting
This emulates the analog bandwidth limitations of composite and S-video signals. High-frequency detail gets rolled off, creating a subtle blur and reducing color fringing on bright-to-dark transitions.
The effect should be invisible at normal viewing distances. You shouldn’t see a blur; you should notice that fine diagonal lines smooth out slightly and that harsh color edges lose their brittleness.
A low-pass filter in the 4-6 MHz range (a reasonable approximation of composite video bandwidth) is subtle but correct. Many presets don’t include this because it’s not visually dramatic, but it’s important for color accuracy and realism.
### Gamma and black level
CRT displays had nonlinear brightness response. A signal level of 50% didn’t produce 50% brightness—it produced roughly 20-25% brightness due to the electron gun’s exponential response. This is gamma correction, typically expressed as an exponent (usually 2.2 for standard displays, 2.4 for arcade environments).
Modern displays typically use 2.2 gamma as well, but the emulation should account for the original signal’s gamma. Arcade RGB signals were often at 2.0 gamma. Composite signals were supposed to be 2.2.
Black level is equally important. CRT monitors had a nonzero black level—they couldn’t achieve true zero light output due to stray electron gun emissions and ambient room light reflection. The monitor was typically calibrated so that the darkest part of an image was 2-4% of peak brightness, not true black.
Setting black to true zero (which modern displays do by default) loses shadow detail and makes the image look higher contrast than it should. A black level of 2-3% is more accurate to the original experience.
## Practical configuration: Finding your baseline
The mistake most people make is chasing a single “correct” setting across all content. Instead, you need different presets for different source material.
**For arcade games:** Use a preset based on arcade monitor characteristics. This typically means stronger scanlines (50-60%), modest bloom (1.0 pixels), 2-3% barrel distortion, P4 phosphor colors, and 2.0 gamma. Scanline aspect ratio should match the original cabinet (usually 4:3 with slightly wide pixels).
**For home consoles (NTSC):** Slightly lighter scanlines (40-50%), similar bloom, minimal barrel distortion (under 1%), and 2.2 gamma. Pixel aspect ratio around 1.09:1.
**For home consoles (PAL):** Same as NTSC but with pixel aspect ratio around 1.44:1 and possibly slightly different phosphor colors if emulating European CRT sets.
**For vector arcade games:** No scanlines, no barrel distortion, very light bloom if any, perfect geometry. These games were designed to look sharp and precise on specialized vector monitors.
To find your baseline, start with a community preset that matches your target hardware. RetroArch’s CRT-Royale shader is a good starting point for most applications. Load a game you know well—something you’ve played on original hardware.
Adjust one parameter at a time: Increase scanline intensity until they become visually obvious, then back off 20%. Adjust bloom until bright areas create a slight halo, then reduce it slightly. Apply barrel distortion at 1-2% and see if it helps or hurts legibility.
The key question for each adjustment: Does this make the image look more like the original hardware, or does it just make it look “retro”? There’s a difference. Authentic usually looks better once you adjust to it.
## Diagnostic procedure: Evaluating your emulation settings
You can’t rely on the subjective “it looks right to me” test. Here’s an objective approach.
**Step 1: Test scanline registration.** Load a game with vertical motion—a scrolling shmup or platformer. Pause the game and look at the scanlines. They should remain aligned with the raster lines of the image; they shouldn’t shimmer or swim as the image moves. If they do, your emulation is decoupling them from the actual image timing, which is a shader bug, not an authentic CRT effect.
**Step 2: Test color accuracy.** Load a game with distinct color regions—bright areas against dark areas. Look at the transition. On a proper CRT with phosphor bloom, the transition should be smooth and slightly blurred but not foggy. If it’s harsh and pixelated, your bloom is too low. If it’s so blurred you can’t distinguish adjacent colors, it’s too high.
**Step 3: Test diagonal line rendering.** Load a game with diagonal elements (many shoot-em-ups have diagonal bullet patterns). Watch how the diagonals appear. On a CRT with proper bandwidth limiting and phosphor persistence, they should look smooth and anti-aliased, even though the resolution is very low. On a flat display without emulation, they look jagged. With proper emulation, they should split the difference—smoother than the raw pixels but not blurred into invisibility.
**Step 4: Verify aspect ratio.** Load a game you know was designed for a specific aspect ratio (e.g., an NES game designed for 4:3 with slightly wide pixels). On an original display, characters look correct—not stretched, not squished. With proper pixel aspect ratio emulation, they should look identical. If they look stretched or compressed, your aspect ratio is wrong.
**Step 5: Check shadow detail.** Load a dark area of a game—a cave, a night scene, or a dark corridor. You should be able to distinguish different shades of gray in the dark areas. If all the shadows blend together into pure black, your gamma curve or black level is too high contrast. If the shadows look washed out and gray, your gamma is wrong.
## Edge cases and complications
CRT emulation seems straightforward until you account for real-world variation.
**Mixed signal quality.** Some games on the same system might have been programmed to different signal specs. An arcade machine might have received multiple game ROMs, some designed for RGB output, some for composite. Using the same emulation settings for both is a compromise.
The solution: Create separate presets. For example, in RetroArch, you can set per-game overrides, so a specific ROM loads with its own shader settings.
**Viewing distance and room environment.** Scanlines that are invisible at 6 feet become obvious at 18 inches. A heavily bloom-saturated image looks correct in a dark room but washed out in bright daylight. There’s no universal “correct” setting.
Your best move: Calibrate for your actual viewing conditions. If you’re playing from a couch 8 feet away, dial in settings that work at that distance. If you’re playing at an arcade cabinet distance (3-4 feet), adjust accordingly.
**Display resolution limitations.** Some displays and hardware (especially mobile devices or budget laptops) can’t render complex shader effects in real-time. You may have to choose between perfect emulation and playable framerates.
This is where dedicated hardware solutions like FPGA emulation shine, though they require more investment. For software emulation, reduce shader complexity: choose simpler presets, disable bloom if necessary, use lower-resolution scanlines.
**Game-specific visual design.** Some older games used specific visual tricks that modern displays expose. For example, games that relied on color fringing at composite signal boundaries look wrong with proper RGB emulation. Games with intentional flicker (used to simulate transparency or animation) look different on displays without the phosphor persistence that made the flicker less obvious.
These aren’t emulation failures; they’re artifacts of how the games were made for specific hardware. Understanding them is part of accurate emulation.
**Consumer CRT variation.** Home TV sets had dramatically different characteristics from arcade monitors. A Commodore 64 hooked to a 1980s living room television had different scanline visibility, color response, and geometric characteristics than an arcade cabinet. Attempting to match arcade standards for a home console game is historically inaccurate.
When in doubt, research the original target hardware. An Atari 2600 was designed for NTSC television sets, not arcade monitors. Adjust your emulation accordingly.
## Integrating CRT emulation into your setup
CRT emulation isn’t just shader selection. It’s part of a broader display pipeline that includes upscaling, interpolation, and filtering.
If you’re using modern displays with HDMI or DisplayPort input, your signal path is: emulator output → upscaling/interpolation → CRT shader → display. Each step affects image quality.
For best results: Disable any upscaling within your emulator (use 1x integer scaling or turn upscaling off). Let the CRT shader handle the expansion to your display’s native resolution. This preserves the shader’s ability to render scanlines and geometry correctly.
Disable any additional sharpening filters or anti-aliasing. The CRT shader includes bandwidth limiting and phosphor bloom that serve as anti-aliasing. Additional sharpening counteracts this and creates artifacts.
If your hardware can’t handle full-complexity CRT shaders, use a two-step process: integer-scale the image with a simple filtering algorithm, then apply a simpler CRT shader that only handles scanlines and basic bloom.
## The honest assessment: When CRT emulation reaches its limits
Perfect CRT emulation is impossible. A CRT monitor was a unique physical device with hundreds of individual calibration parameters, aging characteristics, and environmental factors. No two CRT displays looked identical. Recreating a specific monitor’s exact appearance in software is technically infeasible.
What’s achievable is capturing the core visual characteristics: scanlines, phosphor glow, bandwidth limiting, and geometry distortion. This gets you 90-95% of the way there. The remaining 5-10% is specificity to individual monitors that no emulation can fully capture.
Additionally, CRT emulation software quality varies significantly. A well-designed shader (like CRT-Royale or Lottes) incorporates proper timing, color space conversions, and realistic phosphor models. A hastily made one might apply scanlines and bloom without accounting for how they should interact with the actual image data.
Choose your emulation software carefully. Test presets from multiple sources. Accept that “good enough” might be the realistic target, not “identical to original hardware.”
## Decision framework: Are your CRT emulation settings correct?
Use this checklist to evaluate whether your current settings are working:
1. **Scanlines are visible and aligned with game image motion.** If they’re invisible or shimmering, adjust intensity up or fix the shader implementation.
2. **Bright pixels create a subtle halo but don’t overwhelm the image.** Bloom should enhance perceived resolution, not destroy it. If you can’t read on-screen text clearly, bloom is too high.
3. **Diagonal lines appear smooth.** Raw pixels create visible jagging. Proper emulation smooths them without blurring them into illegibility.
4. **Colors match your memory of the original hardware.** This is subjective but testable: if you have access to original hardware, compare side-by-side. The emulated version should look similar in color saturation, black levels, and overall contrast.
5. **Character sprites and text remain crisp.** The emulation should enhance visual clarity, not reduce it. If fine details become mushy, something is wrong.
6. **Framerate remains stable.** CRT emulation shouldn’t cause stuttering or frame drops. If it does, reduce shader complexity.
If you’re hitting all these points, your settings are likely appropriate. If you’re missing several, spend time adjusting. The investment will pay dividends across hundreds of hours of retro gaming.