PenTile matrix family
Encyclopedia
PenTile matrix family refers to a family of patented subpixel matrix schemes used in electronic device displays
. PenTile is a trademark of Samsung.
These subpixel layouts are specifically designed to operate with a proprietary set of subpixel rendering algorithms embedded in the display driver, allowing plug and play compatibility with conventional RGB Stripe panels.
comprising two red subpixels, two green subpixels, and one central blue subpixel in each unit cell. It was inspired by biomimicry of the human retina
which has nearly equal numbers of L and M type cone cells
, but significantly fewer S cones. As the S cones are primarily responsible for perceiving blue colors, which do not appreciably affect the perception of luminance
, reducing the number of blue subpixels with respect to the red and green subpixels in a display does not reduce the image quality. This layout is specifically designed to work with and be dependent upon subpixel rendering that uses only one and a quarter subpixel per pixel, on average, to render an image. That is, that any given input pixel is mapped to either a red centered logical pixel, or a green centered logical pixel.
PenTile was invented by Candice H. Brown Elliott. The technology was licensed by the company Clairvoyante from 2000 until 2008, during which time several prototype PenTile displays were developed by a number of Asian LCD manufacturers. In March 2008, Samsung Electronics acquired Clairvoyante’s PenTile IP assets. Samsung then funded a new company, Nouvoyance, Inc. to continue development of the PenTile technology.
The PenTile RGBW layout uses each red, green, blue and white subpixel to present high-resolution luminance information to the human eyes' red-sensing and green-sensing cone cell
s, while using the combined effect of all the color subpixels to present lower-resolution chroma (color) information to all three cone cell types. Combined, this optimizes the match of display technology to the biological mechanisms of human vision. The layout uses one third fewer subpixels for the same resolution as the RGB Stripe (RGB-RGB) layout, in spite of having four color primaries instead of the conventional three, using subpixel rendering combined with metamer
rendering. Metamer rendering optimizes the energy distribution between the white subpixel and the combined red, green, and blue subpixels: W <> RGB, to improve image sharpness.
The display driver chip has an RGB to RGBW color vector space converter and gamut mapping algorithm, followed by metamer and subpixel rendering
algorithms. In order to maintain saturated color quality, to avoid simultaneous contrast error between saturated colors and peak white brightness, while simultaneously reducing backlight power requirements, the display backlight brightness is under control of the PenTile driver engine. When the image is mostly desaturated colors, those near white or grey, the backlight brightness is significantly reduced, often to less than 50% peak, while the Liquid Crystal Display levels are increased to compensate. When the image has very bright saturated colors, the backlight brightness is maintained at higher levels. Since most natural images and black on white text have few simultaneously bright and saturated colors, the average power of the PenTile RGBW panel is 50% less than a conventional RGB LCD. Since the LCD backlight is the major power using component on many portable devices such as cell phones and personal media players, products that use the PenTile RGBW panel have longer battery life. The PenTile RGBW also has an optional high brightness mode that doubles the brightness of the desaturated color image areas, such as black&white text, for improved outdoor view-ability.
The Motorola es400 and Motorola Atrix 4G
cell phones use PenTile RGBW LCD displays.
is most sensitive to green, especially for high resolution luminance information. Thus the RG-BG scheme creates a color display with one third fewer subpixels than a traditional RGB-RGB scheme but with the same measured luminance display resolution
. This is similar to the Bayer filter
commonly used in digital cameras.
The Google
/HTC
Nexus One
Android phone uses an AMOLED display by Samsung
that uses PenTile RGBG technology as does the Samsung S8000
(although this is stated via numerous sources and can be verified with a magnifier, no information directly from Samsung
states this)
. The Samsung i9000 Galaxy S
and Samsung Wave S8500
series phones use a Super AMOLED
PenTile RGBG panel. The Samsung NX10
camera also uses the PenTile AMOLED display for the rear screen.. The newly released Galaxy Nexus
phone also carries a PenTile RGBG Super Amoled 720p HD display.
The origin of the controversy surrounding measuring resolution lies in the fact that for RGB stripe color subpixelated displays, both definitions give the same measurement.
However, not all color displays have well defined RGB triplets (e.g. color Cathode Ray Tube
). The display industry standard method of measuring and defining resolution in color displays, as originated by the Video Electronics Standards Association (VESA
) currently maintained by the International Committee for Display Metrology of the Society for Information Display
, is to measure the contrast of line pairs, requiring a minimum of 50% Michelson Contrast
for displays intended for rendering text.
The developers of PenTile displays use this VESA criterion for contrast of line pairs to calculate the resolutions claimed. However, for the same resolution and size the PenTile screen can appear grainy, pixelated, speckled, with blurred text on some saturated colors and backgrounds when compared to RGB stripe color. This effect is understood to be caused by the restriction of the number of subpixels that may participate in the image reconstruction when the color is fully saturated. In the RGBW case, this is caused as the W subpixel will not be available in order to maintain the saturated color. In the RGBG case, this will occur when the color is saturated red, as the fully populated (one green per pixel) will not be available. For all other cases, text and especially full color images are fully reconstructed.
Electronic visual display
An electronic visual display is display technology which incorporates flat panel displays, performs as a video display, output device for presentation of images transmitted electronically, for visual reception, without producing a permanent record....
. PenTile is a trademark of Samsung.
These subpixel layouts are specifically designed to operate with a proprietary set of subpixel rendering algorithms embedded in the display driver, allowing plug and play compatibility with conventional RGB Stripe panels.
History
"PenTile Matrix" (a neologism from penta-, meaning "five" and tile) describes the geometric layout of the prototypical subpixel arrangement developed in the early 1990s. The layout consists of a quincunxQuincunx
A quincunx is a geometric pattern consisting of five points arranged in a cross, that is five coplanar points, four of them forming a square or rectangle and a fifth at its center...
comprising two red subpixels, two green subpixels, and one central blue subpixel in each unit cell. It was inspired by biomimicry of the human retina
Retina
The vertebrate retina is a light-sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical...
which has nearly equal numbers of L and M type cone cells
Cone cell
Cone cells, or cones, are photoreceptor cells in the retina of the eye that are responsible for color vision; they function best in relatively bright light, as opposed to rod cells that work better in dim light. If the retina is exposed to an intense visual stimulus, a negative afterimage will be...
, but significantly fewer S cones. As the S cones are primarily responsible for perceiving blue colors, which do not appreciably affect the perception of luminance
Luminance
Luminance is a photometric measure of the luminous intensity per unit area of light travelling in a given direction. It describes the amount of light that passes through or is emitted from a particular area, and falls within a given solid angle. The SI unit for luminance is candela per square...
, reducing the number of blue subpixels with respect to the red and green subpixels in a display does not reduce the image quality. This layout is specifically designed to work with and be dependent upon subpixel rendering that uses only one and a quarter subpixel per pixel, on average, to render an image. That is, that any given input pixel is mapped to either a red centered logical pixel, or a green centered logical pixel.
PenTile was invented by Candice H. Brown Elliott. The technology was licensed by the company Clairvoyante from 2000 until 2008, during which time several prototype PenTile displays were developed by a number of Asian LCD manufacturers. In March 2008, Samsung Electronics acquired Clairvoyante’s PenTile IP assets. Samsung then funded a new company, Nouvoyance, Inc. to continue development of the PenTile technology.
PenTile RGBW
PenTile RGBW technology adds a white subpixel to the traditional red, blue, and green subpixels in a color display allowing a brighter display using less power.The PenTile RGBW layout uses each red, green, blue and white subpixel to present high-resolution luminance information to the human eyes' red-sensing and green-sensing cone cell
Cone cell
Cone cells, or cones, are photoreceptor cells in the retina of the eye that are responsible for color vision; they function best in relatively bright light, as opposed to rod cells that work better in dim light. If the retina is exposed to an intense visual stimulus, a negative afterimage will be...
s, while using the combined effect of all the color subpixels to present lower-resolution chroma (color) information to all three cone cell types. Combined, this optimizes the match of display technology to the biological mechanisms of human vision. The layout uses one third fewer subpixels for the same resolution as the RGB Stripe (RGB-RGB) layout, in spite of having four color primaries instead of the conventional three, using subpixel rendering combined with metamer
Metamerism (color)
In colorimetry, metamerism is the matching of apparent color of objects with different spectral power distributions. Colors that match this way are called metamers....
rendering. Metamer rendering optimizes the energy distribution between the white subpixel and the combined red, green, and blue subpixels: W <> RGB, to improve image sharpness.
The display driver chip has an RGB to RGBW color vector space converter and gamut mapping algorithm, followed by metamer and subpixel rendering
Subpixel rendering
Subpixel rendering is a way to increase the apparent resolution of a computer's liquid crystal display or Organic Light Emitting Diode display by rendering pixels to take into account the screen type's physical properties...
algorithms. In order to maintain saturated color quality, to avoid simultaneous contrast error between saturated colors and peak white brightness, while simultaneously reducing backlight power requirements, the display backlight brightness is under control of the PenTile driver engine. When the image is mostly desaturated colors, those near white or grey, the backlight brightness is significantly reduced, often to less than 50% peak, while the Liquid Crystal Display levels are increased to compensate. When the image has very bright saturated colors, the backlight brightness is maintained at higher levels. Since most natural images and black on white text have few simultaneously bright and saturated colors, the average power of the PenTile RGBW panel is 50% less than a conventional RGB LCD. Since the LCD backlight is the major power using component on many portable devices such as cell phones and personal media players, products that use the PenTile RGBW panel have longer battery life. The PenTile RGBW also has an optional high brightness mode that doubles the brightness of the desaturated color image areas, such as black&white text, for improved outdoor view-ability.
The Motorola es400 and Motorola Atrix 4G
Motorola Atrix 4G
The Motorola Atrix 4G is a high-end Android-based smartphone by Motorola, introduced in CES 2011 on January 5, 2011. It was made available in the first quarter of 2011. It was introduced along with three other products, Motorola Xoom, Motorola Droid Bionic, and Motorola Cliq 2. It uses an NVIDIA...
cell phones use PenTile RGBW LCD displays.
PenTile RGBG
PenTile RGBG layout uses green pixels interleaved with alternating red and blue pixels. The human eyeHuman eye
The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...
is most sensitive to green, especially for high resolution luminance information. Thus the RG-BG scheme creates a color display with one third fewer subpixels than a traditional RGB-RGB scheme but with the same measured luminance display resolution
Display resolution
The display resolution of a digital television or display device is the number of distinct pixels in each dimension that can be displayed. It can be an ambiguous term especially as the displayed resolution is controlled by all different factors in cathode ray tube , flat panel or projection...
. This is similar to the Bayer filter
Bayer filter
A Bayer filter mosaic is a color filter array for arranging RGB color filters on a square grid of photosensors. Its particular arrangement of color filters is used in most single-chip digital image sensors used in digital cameras, camcorders, and scanners to create a color image...
commonly used in digital cameras.
The Google
Google
Google Inc. is an American multinational public corporation invested in Internet search, cloud computing, and advertising technologies. Google hosts and develops a number of Internet-based services and products, and generates profit primarily from advertising through its AdWords program...
/HTC
HTC
-Companies:*HTC Corporation, a Taiwanese manufacturer of handheld devices*Harrisonville Telephone Company, a telephone company in Waterloo, Illinois*Horry Telephone Cooperative, a telephone cooperative in Horry County, South Carolina...
Nexus One
Nexus One
The Nexus One was Google's flagship smartphone manufactured by Taiwan's HTC Corporation. It became available on January 5, 2010 and uses the Android open source mobile operating system...
Android phone uses an AMOLED display by Samsung
Samsung
The Samsung Group is a South Korean multinational conglomerate corporation headquartered in Samsung Town, Seoul, South Korea...
that uses PenTile RGBG technology as does the Samsung S8000
Samsung S8000
Samsung Jet , is a touch screen phone released in June 2009 by Samsung. It features an 800 MHz processor and a new WebKit browser called Dolfin, which will be available on Samsung phones in the future.-Specification:...
(although this is stated via numerous sources and can be verified with a magnifier, no information directly from Samsung
Samsung
The Samsung Group is a South Korean multinational conglomerate corporation headquartered in Samsung Town, Seoul, South Korea...
states this)
. The Samsung i9000 Galaxy S
Samsung i9000 Galaxy S
The Samsung Galaxy S is an Android smartphone that was announced by Samsung in March 2010. It features a 1 GHz ARM "Hummingbird" processor, 8–16 GB internal Flash memory, a 4-inch 480×800 pixel Super AMOLED capacitive touchscreen display, Wi-Fi connectivity, a 5-megapixel camera with a...
and Samsung Wave S8500
Samsung Wave S8500
The Samsung Wave GT-S8500 is the first touchscreen smartphone running the new bada operating system designed by Samsung, which was commercially released on June 1, 2010...
series phones use a Super AMOLED
Super AMOLED
Super Active-Matrix Organic Light-Emitting Diode or Super AMOLED is a display technology mainly for use in mobile devices such as mobile phones...
PenTile RGBG panel. The Samsung NX10
Samsung NX10
The Samsung NX10 is a 14.0 effective megapixel APS-C crop CMOS mirrorless interchangeable lens digital camera made by Samsung. It was announced on January 4, 2010...
camera also uses the PenTile AMOLED display for the rear screen.. The newly released Galaxy Nexus
Galaxy Nexus
The Galaxy Nexus is a touchscreen slate Android smartphone developed by a partnership between Samsung and Google. The phone and operating system were developed collaboratively by engineers from both companies. It is the third generation successor to Google’s previous flagship phones, the Nexus One...
phone also carries a PenTile RGBG Super Amoled 720p HD display.
Controversy
An early controversy regarding the definition or measurement of resolution of color subpixelated flat panel displays in general, and for subpixel rendered displays in particular led many people to question the resolution claims of PenTile display products. One school holds that resolution is defined by the number of red, green, and blue subpixels, in groups of three, in an array in each axis. The other school holds that resolution is found by counting the number of line pairs, black & white (or bright and dark) lines and spaces that may be simultaneously rendered on the screen, in each axis.The origin of the controversy surrounding measuring resolution lies in the fact that for RGB stripe color subpixelated displays, both definitions give the same measurement.
However, not all color displays have well defined RGB triplets (e.g. color Cathode Ray Tube
Cathode ray tube
The cathode ray tube is a vacuum tube containing an electron gun and a fluorescent screen used to view images. It has a means to accelerate and deflect the electron beam onto the fluorescent screen to create the images. The image may represent electrical waveforms , pictures , radar targets and...
). The display industry standard method of measuring and defining resolution in color displays, as originated by the Video Electronics Standards Association (VESA
VESA
VESA is an international standards body for computer graphics founded in 1989 by NEC Home Electronics and eight other video display adapter manufacturers.VESA's initial goal was to produce a standard for 800×600 SVGA resolution video displays...
) currently maintained by the International Committee for Display Metrology of the Society for Information Display
Society for Information Display
The Society for Information Display is an industry organization for displays, generally electronic displays such as televisions and computer monitors. SID was founded in 1962. Its main activities are publishing technical journals and running Display Week, its main conference, held in May each year...
, is to measure the contrast of line pairs, requiring a minimum of 50% Michelson Contrast
Contrast (vision)
Contrast is the difference in visual properties that makes an object distinguishable from other objects and the background. In visual perception of the real world, contrast is determined by the difference in the color and brightness of the object and other objects within the same field of view...
for displays intended for rendering text.
The developers of PenTile displays use this VESA criterion for contrast of line pairs to calculate the resolutions claimed. However, for the same resolution and size the PenTile screen can appear grainy, pixelated, speckled, with blurred text on some saturated colors and backgrounds when compared to RGB stripe color. This effect is understood to be caused by the restriction of the number of subpixels that may participate in the image reconstruction when the color is fully saturated. In the RGBW case, this is caused as the W subpixel will not be available in order to maintain the saturated color. In the RGBG case, this will occur when the color is saturated red, as the fully populated (one green per pixel) will not be available. For all other cases, text and especially full color images are fully reconstructed.
See also
- Subpixel renderingSubpixel renderingSubpixel rendering is a way to increase the apparent resolution of a computer's liquid crystal display or Organic Light Emitting Diode display by rendering pixels to take into account the screen type's physical properties...
- Nexus OneNexus OneThe Nexus One was Google's flagship smartphone manufactured by Taiwan's HTC Corporation. It became available on January 5, 2010 and uses the Android open source mobile operating system...
- Samsung i9000 Galaxy SSamsung i9000 Galaxy SThe Samsung Galaxy S is an Android smartphone that was announced by Samsung in March 2010. It features a 1 GHz ARM "Hummingbird" processor, 8–16 GB internal Flash memory, a 4-inch 480×800 pixel Super AMOLED capacitive touchscreen display, Wi-Fi connectivity, a 5-megapixel camera with a...
- Samsung Wave S8500Samsung Wave S8500The Samsung Wave GT-S8500 is the first touchscreen smartphone running the new bada operating system designed by Samsung, which was commercially released on June 1, 2010...