A CRT scanline effect adds thin, evenly spaced dark lines across an image so it looks like it’s being shown on an old tube TV or arcade monitor. On a pixelated photo, it’s the finishing touch that turns “retro filter” into “screenshot from 1989.” It works best with a coarse pixel grid and a palette from a TV-era console like the NES, and it’s a different effect from a VHS filter, which imitates videotape rather than the screen.
What were scanlines on a CRT? #
A cathode-ray tube (CRT) draws the picture one horizontal line at a time, sweeping a beam across the screen from top to bottom. Each of those lines is a scan line. According to Wikipedia’s scan line article, when a CRT shows a progressive signal at less than its maximum vertical resolution, the lines become visible even from a distance, as alternating colored lines and black lines.
Many classic consoles sent exactly that kind of low-resolution signal, so games on a CRT had faint dark gaps between rows of pixels. Wikipedia notes the look is now used deliberately as a visual effect, and emulators often offer a scanline mode to recreate it.
Scanlines, CRT effects and VHS: what’s the difference? #
These get lumped together, but they’re separate effects that imitate different things:
| Effect | What it imitates | What it looks like |
|---|---|---|
| Scanlines | Gaps between lines on a CRT | Thin, regular dark horizontal lines |
| Screen curvature and vignette | The curved glass of a tube | Bowed edges, darker corners |
| Phosphor glow or bloom | Bright pixels bleeding light | Soft halos around light areas |
| Shadow mask or aperture grille | The screen’s colored phosphor pattern | Fine RGB dots or vertical stripes |
| VHS | Videotape recording and playback | Smeared color, noise, wobbly tracking lines, softness |
A pixel-art scanline effect only does the first one. If you want tape wobble and color bleed, you need a VHS filter, and that’s a video look, not a pixel-art one.
When does a scanline effect look right? #
Scanlines suit anything that would have been shown on a TV or arcade monitor:
- NES and Sega Master System looks. Those consoles were played on CRT TVs. Our NES-style photo guide pairs well with scanlines.
- Arcade looks. Bold palettes, big pixels and outlines.
- Home computer looks. Commodore 64 and ZX Spectrum machines were often plugged into TVs.
They’re less authentic for:
- Game Boy looks. The Game Boy had an LCD, not a CRT, so a Game Boy style photo looks more convincing without them.
- Modern pixel art. PICO-8-style and modern indie looks are usually shown sharp, with no screen effects.
That said, it’s your picture. Scanlines on a vaporwave palette look great, even if no 1980s TV ever showed those colors.
How scanlines work in a pixel art converter #
In a pixel-art tool, scanlines usually line up with the pixel grid rather than the file’s actual pixels. That way each row of big pixels gets one dark line, the way a row of game pixels would on a CRT.
In Pixelize, the CRT scanlines toggle on the FX tab darkens the bottom slice of every row of cells after the image has been enlarged to its output size. Because the lines are tied to the cell grid, the effect scales with your pixel size: 32 px blocks get bold, chunky lines, and 4 px blocks get fine ones. The preview and the export are drawn by the same code, so the lines you see are the lines you save. The app has no VHS, curvature or glow effects, just clean scanlines.
How to add a CRT scanline effect to a photo #
- In Pixelize, tap Choose Photo or Take Photo.
- On the Pixel tab, choose 8px, 12px or 16px. Scanlines are most readable at these sizes. At 4 px they’re very fine, and at 32 px they’re very bold.
- On the Color tab, pick a TV-era palette such as NES, Sega Master System or Commodore 64, or a mood palette like Sunset or Vapor Wave.
- On the FX tab, turn on CRT scanlines. Add Outline for sprite-like edges.
- On Adjust, raise Brightness a little. Scanlines darken part of every row, so the whole image gets a bit darker.
- Export at XL (up to a 2160-pixel long edge) so the lines stay crisp.
The app is free on iPhone and Android and does all of this on the phone, without uploading your photo.
How to add scanlines in a desktop editor #
Any editor with layers can do it by hand:
- Convert and enlarge your pixel art first, using nearest-neighbor at a whole-number scale.
- Add a new layer on top.
- Draw evenly spaced horizontal black lines, one per row of pixel-art cells. For art enlarged 8x, that’s a 2 to 3 pixel line every 8 pixels.
- Set the layer to Multiply and lower the opacity to around 40 to 50% until the lines feel right.
Tips for a better scanline look #
- Compensate for the darkening. Brighten before or after adding scanlines so midtones don’t turn muddy.
- Keep dithering light. Dither patterns plus scanlines can look busy. Try None or Ordered.
- Export big. When a social app shrinks an image full of fine repeating lines, it can create moiré, a shimmering wavy pattern. Larger exports and coarser pixel sizes reduce the risk.
- Don’t stack every effect. Scanlines, outlines and heavy dithering all at once can overwhelm a small image. Add one at a time and compare.
What about a VHS effect? #
VHS is a different kind of retro. It comes from home-video tape: soft detail, colors bleeding sideways, noise, and the rolling bands of a badly tracked tape. It’s a staple of the vaporwave aesthetic. Wikipedia’s vaporwave article lists VHS degradation as a common effect. Pixelize doesn’t have a VHS filter, so for tape artifacts you’ll need a dedicated VHS or glitch app. For the pixel side of vaporwave, see how to make a vaporwave pixel art photo.
Frequently asked questions #
What are scanlines in retro games? #
They’re the thin dark gaps between lines of the picture on a CRT screen. Consoles that sent a low-resolution signal left visible dark lines between rows of pixels, and many people now associate that look with classic games.
Is a CRT effect the same as a VHS effect? #
No. A CRT effect imitates the screen (scanlines, curvature, glow). A VHS effect imitates the tape (smeared color, noise, tracking lines). They’re often combined in retro edits, but they’re separate.
Why do scanlines make my picture darker? #
Scanlines darken a slice of every row, which lowers the overall brightness. Raise brightness a little to compensate.
Should I add scanlines to Game Boy pixel art? #
For authenticity, no. The Game Boy used an LCD screen, not a CRT. Scanlines suit NES, arcade and home-computer looks better.
How do I add scanlines to a photo on my phone? #
Use a pixel-art or retro app with a scanline option. In Pixelize, convert your photo, then turn on CRT scanlines on the FX tab and export.