Hold your eyes on the screen and the picture is flawless. Flick them toward a doorframe mid-scene, or blink during a bright pan, and something leaks out of the frame: a comet-tail of red, green, and blue fringes chasing a white shirt or a subtitle, gone before you can study it. Projector owners have blamed cables, dust, and their own glasses, but the artifact is documented in the display-engineering literature under a precise name—color breakup, familiar to buyers as the rainbow effect. It is not a defect in your unit. It is the visible edge of a strategy the projector uses to build every color on screen out of only one chip, and it belongs to the same class of evidence as the moiré rainbows that appear when you photograph a monitor: color that exists only in the meeting of a display's construction and your eye's construction.
One chip, three flashes
A single-chip DLP projector owns exactly one imaging device: a mirror chip whose hundreds of thousands of tiny mirrors tilt to shade each pixel. Mirrors have no color of their own—they only aim light. So the projector bolts a wheel containing red, green, and blue filter segments into the beam and spins it. For a few thousandths of a second the entire screen is painted in red light only; then the wheel rotates and the whole screen is repainted in green; then blue. Red, green, and blue alternate so fast—each frame's colors delivered in a rapid succession of fields—that a still, fixating eye fuses them into one stable image, the same way flickering frames fuse into motion. Reviews of color-breakup assessment in the Society for Information Display's journal survey how this artifact is measured and why it became the benchmark complaint of single-chip projection: whenever the observer's gaze moves relative to the screen, successive color fields no longer land on the same retinal spots. Your eye crosses the screen during the red field, keeps moving during the green, and continues during the blue, so each color lands slightly displaced along the path of motion. White or bright objects—which are built from all three fields—leave a rainbow smear because their red, green, and blue copies are stamped a few image-widths apart on your retina. Hold still, and the copies stack again.
Why some people see them and some never do
Sensitivity is genuinely individual. The smears are easiest to trigger with quick saccades, blinking, or tracking fast motion across high-contrast whites—titles, hockey ice, subtitles in dark scenes. Some viewers report them instantly and cannot unsee them; others watch for years and never notice, and both reports are honest. Display researchers treat color breakup as a measurable property of field-sequential systems, with the magnitude depending on wheel speed, the number of color segments, and image brightness. Bright objects betray the system because white is the one color built from all three fields at full intensity: every displaced copy of a white edge is a saturated stripe waiting to separate, where a mostly-red object can only smear into red and darker red. Texas Instruments' own engineering notes on DLP technology describe how faster color wheels and more segments were adopted specifically to shrink the artifact—each additional pass of the color cycle compresses the displacement between red, green, and blue copies on a moving retina.
The artifact also explains a market segmentation most buyers never hear explained. Three-chip projectors—DLP, LCoS, or LCD-based—split white light into red, green, and blue paths that illuminate three separate imagers simultaneously; all colors are delivered at once, so there is no sequence for eye motion to expose, at the price of a larger, more complicated optical engine. Modern lampless single-chip projectors using LED or laser sources can also run their color sequence far faster than a mechanical wheel ever spun. If you are the sensitive kind of viewer, that is the shopping criterion hidden inside the spec sheet.
A nice experiment in your own living room
You do not need lab equipment to see the seams of field-sequential color. Play high-contrast content on any single-chip projector, dim the room, and dart your eyes deliberately across a bright edge—the fringes will appear along the path of motion and vanish the moment your gaze settles. A camera panning its sensor across the screen records the same breakup, trailing color copies of bright objects. It is one of the cleanest ways to catch a display in the act of building color, the home-theater sibling of noticing why a backlit TV's black glows gray in a dark room: the moment you know how the trick is performed, the artifact becomes legible rather than annoying. If a store will demo a projector before you buy, this is the thirty-second test worth running—white-on-black credits, deliberate eye flicks, and an honest answer about whether you can unsee what you just saw. Training your eye to catch fleeting color events also pays off in small ways—see how quickly you can find an odd tile in Spot the Different, a game built entirely on one-glance discrimination.
Still eye: the three copies stack into one white edge. Moving eye: they land apart, and the edge smears into a rainbow trail. Labels mark each copy, so the offset story survives without color.