page_title: Digital Light Processing
section_title: The color wheel "rainbow effect"
hierarchical_section_title: Digital Light Processing / Color in DLP projection / Single-chip projectors / The color wheel "rainbow effect"
caption_attribution_description: Photo taken of a hand moving quickly past a DLP projection, demonstrating the rainbow effect of a DLP projector's colour wheel. (This is an Acer PD100) Author: Damien Donnelly
context_page_description: Digital Light Processing is a set of chipsets based on optical micro-electro-mechanical technology that uses a digital micromirror device. It was originally developed in 1987 by Larry Hornbeck of Texas Instruments. While the DLP imaging device was invented by Texas Instruments, the first DLP-based projector was introduced by Digital Projection Ltd in 1997. Digital Projection and Texas Instruments were both awarded Emmy Awards in 1998 for the DLP projector technology. DLP is used in a variety of display applications from traditional static displays to interactive displays and also non-traditional embedded applications including medical, security, and industrial uses.
  DLP technology is used in DLP front projectors, DLP rear projection television sets, and digital signs. It is also used in about 85% of digital cinema projection, and in additive manufacturing as a light source in some printers to cure resins into solid 3D objects.
  Smaller "pico" chipsets are used in mobile devices including cell phone accessories and projection display functions embedded directly into phones.
context_section_description: DLP projectors utilizing a mechanical spinning color wheel may exhibit an anomaly known as the "rainbow effect". This is best described as brief flashes of perceived red, blue, and green "shadows" observed most often when the projected content features high contrast areas of moving bright or white objects on a mostly dark or black background. Common examples are the scrolling end credits of many movies, and also animations with moving objects surrounded by a thick black outline. Brief visible separation of the colours can also be apparent when the viewer moves their eyes quickly across the projected image. Some people perceive these rainbow artifacts frequently, while others may never see them at all.
  This effect is caused by the way the eye follows a moving object on the projection.  When an object on the screen moves, the eye follows the object with a constant motion, but the projector displays each alternating color of the frame at the same location for the duration of the whole frame.  So, while the eye is moving, it sees a frame of a specific color (red, for example).  Then, when the next color is displayed (green, for example), although it gets displayed at the same location overlapping the previous color, the eye has moved toward the object's next frame target.  Thus, the eye sees that specific frame color slightly shifted.  Then, the third color gets displayed (blue, for example), and the eye sees that frame's color slightly shifted again.  This effect is not perceived only for the moving object, but the whole picture. Multi-color LED-based and laser-based single-chip projectors are able to eliminate the spinning wheel and minimize the rainbow effect, since the pulse rates of LEDs and lasers are not limited by physical motion. Three-chip DLP projectors function without color wheels, and therefore do not manifest this rainbow artifact."
caption: The rainbow effect found in DLP projectors utilizing a mechanical spinning wheel.
exif: {"Image ImageDescription": "OLYMPUS DIGITAL CAMERA", "Image Make": "OLYMPUS IMAGING CORP.", "Image Model": "u-miniD,Stylus V", "Image Orientation": "Horizontal (normal)", "Image XResolution": "314", "Image YResolution": "314", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Version 1.0", "Image DateTime": "0000:00:00 00:00:00", "Image YCbCrPositioning": "Co-sited", "Image ExifOffset": "266", "Image PrintIM": "[80, 114, 105, 110, 116, 73, 77, 0, 48, 50, 53, 48, 0, 0, 20, 0, 1, 0, 20, 0, ... ]", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "7092", "Thumbnail JPEGInterchangeFormatLength": "8824", "EXIF ExposureTime": "1/6", "EXIF FNumber": "7/2", "EXIF ExposureProgram": "Program Normal", "EXIF ISOSpeedRatings": "64", "EXIF ExifVersion": "0221", "EXIF DateTimeOriginal": "0000:00:00 00:00:00", "EXIF DateTimeDigitized": "0000:00:00 00:00:00", "EXIF ComponentsConfiguration": "YCbCr", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "361/100", "EXIF MeteringMode": "Pattern", "EXIF LightSource": "Unknown", "EXIF Flash": "Flash did not fire, compulsory flash mode", "EXIF FocalLength": "119/20", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "2272", "EXIF ExifImageLength": "1704", "Interoperability InteroperabilityIndex": "R98", "Interoperability InteroperabilityVersion": "[48, 49, 48, 48]", "EXIF InteroperabilityOffset": "722", "EXIF FileSource": "Digital Camera", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Auto Exposure", "EXIF WhiteBalance": "Auto", "EXIF DigitalZoomRatio": "1", "EXIF SceneCaptureType": "Standard", "EXIF GainControl": "None", "EXIF Contrast": "Normal", "EXIF Saturation": "Normal", "EXIF Sharpness": "Normal"}