220:. These pixel components appear as a single color to the human eye because of blurring by optics and spatial integration by nerve cells in the eye. However, the eye is much more sensitive to the location. Therefore, turning on the G and B of one pixel and the R of the next pixel to the right will produce a white dot, but it will appear to be 1/3 of a pixel to the right of the white dot that would be seen from the RGB of only the first pixel. Subpixel rendering takes advantage of this to provide three times the horizontal resolution of the rendered image, though it has to blur this image to produce the correct color by ensuring the same amount of red, green, and blue are turned on as when no subpixel rendering is being done.
414:, that "offers high quality LCD-optimized output without resorting to ClearType techniques of resolution tripling and filtering". This is the method enabled by default. When using this method, "each color channel is generated separately after shifting the glyph outline, capitalizing on the fact that the color grids on LCD panels are shifted by a third of a pixel. This output is indistinguishable from ClearType with a light 3-tap filter." Since the Harmony method does not require additional filtering, it is not covered by the ClearType patents.
128:
78:
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of the patent by FreeType indicates that the idea of subpixel rendering is not covered by the patent, but by the actual filter used as a last step to balance the color. Microsoft's patent describes the smallest filter possible that distributes each subpixel value to an equal amount of R,G, and B pixels. Any other filter will either be blurrier or will introduce color artifacts.
227:, and gives a smoother result regardless of whether antialiasing is used or not since it artificially increases the resolution. However, it introduces color aliasing since subpixels are colored. Subsequent filtering applied to remove the color artifacts is a form of antialiasing, although its purpose is not smoothing jagged shapes as in conventional antialiasing.
335:
and the purple left half of the next pixel, then the result is a white block that is 1/2 pixel to the right, which is indeed an instance of subpixel rendering. However, it is not clear whether any programmers of the Apple II have considered the pairs of bits as pixels—instead calling each bit a pixel.
195:
in the United States on subpixel rendering technology for text rendering on RGB Stripe layouts. The patents 6,219,025, 6,239,783, 6,307,566, 6,225,973, 6,243,070, 6,393,145, 6,421,054, 6,282,327, 6,624,828 were filed between
October 7, 1998, and October 7, 1999, and expired on July 30, 2019. Analysis
334:
Gibson's example claims that because two adjacent bits make a white block, there are in fact two bits per pixel: one which activates the purple left half of the pixel, and the other which activates the green right half of the pixel. If the programmer instead activates the green right half of a pixel
399:
implementations. The original implementation uses the ClearType antialiasing filters and carries the following notice: "The colour filtering algorithm of
Microsoft's ClearType technology for subpixel rendering is covered by patents; for this reason the corresponding code in FreeType is disabled by
321:
contain seven visible bits (each corresponding directly to a pixel) and a flag bit used to select between purple/green or blue/orange color sets. Each pixel, since it is represented by a single bit, is either on or off; there are no bits within the pixel itself for specifying color or brightness.
230:
Subpixel rendering requires the software to know the layout of the subpixels. The most common reason it is wrong is monitors that can be rotated 90 (or 180) degrees, though monitors are manufactured with other arrangements of the subpixels, such as BGR or in triangles, or with 4 colors like RGBW
338:
The flag bit in each byte affects color by shifting pixels half a pixel-width to the right. This half-pixel shift was exploited by some graphics software, such as HRCG (High-Resolution
Character Generator), an Apple utility that displayed text using the high-resolution graphics mode, to smooth
330:
color encoding scheme, determined by horizontal position: pixels with even horizontal coordinates are always purple (or blue, if the flag bit is set), and odd pixels are always green (or orange). Two lit pixels next to each other are always white, regardless of whether the pair is even/odd or
429:, allowing them to display documents the same way across various operating systems: Windows, MacOS, Linux etc. When it was launched around the year 2001, CoolType supported a wider range of fonts than Microsoft's ClearType, which at the time was limited to
135:, showing various arrangements of pixels and subpixels, which must be considered for subpixel rendering. LCD displays consisting of red, green, and blue subpixels (bottom right is the most typical example) are best suited to subpixel rendering.
215:
A single pixel on a color display is made of several subpixels, typically three arranged left-to-right as red, green, and blue (RGB). The components are easily visible when viewed with a small magnifying glass, such as a
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squares. On any such display the result of incorrect subpixel rendering will be worse than if no subpixel rendering was done at all (it will not produce color artifacts, but it will produce noisy edges).
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odd/even, and irrespective of the value of the flag bit. This is an approximation, but it is what most programmers of the time would have in mind while working with the Apple's high-resolution mode.
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313:, introduced in 1977, supports an early form of subpixel rendering in its high-resolution (280×192) graphics mode. The Wozniak patent only used 2 "sub-pixels". The
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817:
709:
Platt, John; Keely, Bert; Hill, Bill; Dresevic, Bodin; Betrisey, Claude; Mitchell, Don P.; Hitchcock, Greg; Blinn, Jim; Whitted, Turner (2000-05-01).
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46:
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default. Note that subpixel rendering per se is prior art; using a different colour filter thus easily circumvents
Microsoft's patent claims."
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456:. However, it was removed after the introduction of Retina displays. Unlike Microsoft's implementation, which favors a tight fit to the grid (
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patented various implementations with certain technical differences owing to the different purposes their technologies were intended for.
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460:) to maximize legibility, Apple's implementation prioritizes the shape of the glyphs as set out by their designer.
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that states a
Knowledge editor's personal feelings or presents an original argument about a topic.
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FreeType offers a variety of color filters. Since version 2.6.2, the default filter is
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Despite the inherent color anomalies, it can also be used to render general graphics.
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Engelhardt, Thomas (2013). "Low-Cost
Subpixel Rendering for Diverse Displays".
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describing the filtering behind ClearType. It was then made available in
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The origin of subpixel rendering as used today remains controversial.
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616:"A Treatise on Font Rasterisation With an Emphasis on Free Software"
278:. Statements consisting only of original research should be removed.
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535:"ClearType Patents, FreeType and the Unix Desktop: an explanation"
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is a method used to increase the effective resolution of a color
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Since version 2.8.1, a second implementation exists, called
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personal reflection, personal essay, or argumentative essay
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841:", Seybold Report on Internet Publishing, Vol. 4 Issue 8
472: – Process of converting text from vector to raster
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David Turner (24 Sep 20:00 2006) LCD Rendering
Patches
380:, however, could and did change the default setting.)
154:, and uses them as rendering units instead of pixels.
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Microsoft's
Cleartype Sets Off Debate on Originality
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announced its subpixel rendering technology, called
16:
Technique for increasing apparent display resolution
391:, the library used by most current software on the
223:Subpixel rendering does not necessitate the use of
933:http://jankautz.com/publications/SubpixelCGF13.pdf
364:in 1998. Microsoft published a paper in May 2000,
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880:Ron Feigenblatt's remarks on Microsoft ClearType
528:
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637:"GRC - The Origins of Sub-Pixel Font Rendering"
433:fonts, whereas Adobe's CoolType also supported
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902:Article from the Anti-Grain Geometry Project.
764:Engineering Changes to ClearType in Windows 7
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711:"Displaced Filtering for Patterned Displays"
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372:, but it was not activated by default until
885:Pixel Borrowing, ClearType and Antialiasing
425:created their own subpixel renderer called
366:Displaced Filtering for Patterned Displays,
317:that comprise the Apple II high-resolution
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294:Learn how and when to remove this message
157:Subpixel rendering is primarily used for
65:Learn how and when to remove this message
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852:"The Ails Of Typographic Anti-Aliasing"
811:
685:ICT Bill Gates 1998 keynote comdex 1998
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839:ClearType, CoolType: The Eyes Have It
1365:List of computer graphics algorithms
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566:. FreeType.org. February 13, 2018.
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81:A simulation of subpixel rendering
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483: – Electronic device display
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647:from the original on 2006-03-06
596:from the original on 2011-06-03
570:from the original on 2018-11-10
541:from the original on 2009-03-31
322:Color is instead created as an
812:Lemberg, Werner (2017-09-16).
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120:channel separated and animated
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900:Texts Rasterization Exposures
533:David Turner (June 1, 2007).
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146:. It takes advantage of each
108:The previous image, with the
1137:Hidden-surface determination
837:Felici, James (April 2000) "
773:", MSDN blogs, June 23, 2009
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199:Apple was able to use it in
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908:Computer Graphics Forum
590:"LCD Rendering Patches"
1232:Checkerboard rendering
758:(with introduction by
737:Cite journal requires
592:. September 24, 2006.
564:"FreeType and Patents"
191:Microsoft had several
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45:by rewriting it in an
1187:Affine transformation
1166:Surface triangulation
1110:Anisotropic filtering
481:PenTile matrix family
441:equivalent as well).
309:has claimed that the
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854:. November 2, 2009.
487:Sub-pixel resolution
1202:Collision detection
1130:Global illumination
1252:Scanline rendering
1046:Parallax scrolling
1036:Isometric graphics
769:2012-12-18 at the
670:2007-02-08 at the
520:, December 7, 1998
512:2017-04-21 at the
470:Font rasterization
259:possibly contains
140:Subpixel rendering
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47:encyclopedic style
34:is written like a
1386:Computer graphics
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920:10.1111/cgf.12267
895:Subpixel Explorer
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1279:Shear matrix
1242:Path tracing
1227:Cone tracing
1222:Beam tracing
1142:Polygon mesh
1083:3D rendering
911:
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860:. Retrieved
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822:. Retrieved
807:
796:. Retrieved
792:the original
788:freetype.org
787:
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730:cite journal
719:. Retrieved
704:
694:, retrieved
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618:. 2010-09-15
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574:November 29,
572:. Retrieved
543:. Retrieved
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458:font hinting
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307:Steve Gibson
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163:standard DPI
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131:Examples of
61:
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1294:Translation
1247:Ray casting
1237:Ray tracing
1115:Cel shading
1089:Image-based
1070:3D graphics
1051:Ray casting
1000:2D graphics
713:: 296–299.
476:Kell factor
437:(and their
397:open source
339:diagonals.
284:August 2014
207:agreement.
1380:Categories
1358:Algorithms
1212:Reflection
862:2014-08-11
824:2019-04-30
798:2020-11-14
721:2021-11-30
696:2021-11-30
651:2006-03-02
622:2023-11-11
493:References
370:Windows XP
268:improve it
178:Apple Inc.
165:displays.
1337:rendering
1327:animation
1217:Rendering
454:Quartz 2D
358:ClearType
354:Microsoft
349:ClearType
343:ClearType
272:verifying
186:Microsoft
152:subpixels
1332:modeling
1259:Rotation
1197:Clipping
1180:Concepts
1159:Deferred
1125:Lighting
1105:Aliasing
1099:Unbiased
1094:Spectral
856:Archived
818:Archived
767:Archived
715:Archived
690:archived
668:Archived
645:Archived
600:April 9,
594:Archived
568:Archived
545:April 9,
539:Archived
510:Archived
464:See also
450:Mac OS X
439:OpenType
431:TrueType
427:CoolType
418:CoolType
389:FreeType
384:FreeType
324:artifact
311:Apple II
240:Apple II
201:Mac OS X
1264:Scaling
1154:Shading
928:9851327
887:at the
641:grc.com
412:Harmony
326:of the
266:Please
193:patents
172:History
41:Please
1284:Shader
1056:Skybox
1041:Mode 7
1013:Layers
926:
362:COMDEX
184:, and
1304:Voxel
1289:Texel
990:Pixel
924:S2CID
445:macOS
423:Adobe
405:light
360:, at
315:bytes
218:loupe
148:pixel
1028:2.5D
743:help
602:2009
576:2018
547:2009
378:OEMs
328:NTSC
116:and
916:doi
762:) "
516:",
270:by
182:IBM
161:on
1382::
922:.
912:33
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816:.
786:.
734::
732:}}
728:{{
688:,
643:.
639:.
555:^
537:.
525:^
180:,
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118:B
114:G
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