Horizontal raster line in digital imaging — legacy of analog broadcast, visible at low resolution or as intentional effect. Used nostalgically in lo-fi aesthetics.
Those who grew up with CRT screens are familiar with the phenomenon: the electron beam scans the screen line by line, from top to bottom, several times per second. These horizontal raster lines are scan lines— a direct legacy of analog television technology. In the digital age, they are technically long obsolete but stubbornly appear in low-resolution scenarios and are deliberately used as a stylistic device.
On set or in post-production, scan lines are primarily encountered when emulating older image formats. Anyone wanting to simulate a CRT monitor or an old arcade screen—for sci-fi interfaces or hacker sequences, for example—reaches for scan line textures. This is achieved through simple horizontal lines overlaid on the image with reduced opacity. The effect immediately appears "authentically analog" and unconsciously triggers nostalgia. In a 720p simulation, for instance, a slight darkening would be introduced every two to three pixels; at 480p (NTSC standard), the lines become more clearly visible and distinctive.
Practically, this is often solved in After Effects or DaVinci Resolve: a simple striped pattern (black lines on a transparent background) is created in a 50:50 ratio and placed as an overlay layer over the footage. Alternatively, pre-made VFX presets or generator effects are used. The intensity is adjusted via blend modes (Screen, Overlay) and opacity—too aggressive looks cheap, too subtle dissipates the effect. This has no place in documentary or dramatic content; for artificial screen representations (phones, monitors in frame), it is often indispensable.
Important: Scan lines should correspond to the simulated resolution. Showing a modern 4K smart TV does not require visible lines—the eye immediately recognizes the falsity. But for retro gaming, VHS degradation, or interface design in a sci-fi context, the technique still works reliably. It is one of the few remnants of analog image technology that has stubbornly asserted itself in aesthetics—not because it is technically necessary, but because the brain immediately categorizes it as "old" and therefore "real."