Under the current US regime, any minor improvement to a previous technique can be considered an "invention" and "protected" by a patent under the right circumstances (e.g. ĭavid Turner of the FreeType project criticized Gibson's theory as to the invention, at least as far as patent law is concerned, in the following way: «For the record, the Wozniak patent is explicitly referenced in the, and the claims are worded precisely to avoid colliding with it (which is easy, since the Apple II only used 2 "sub-pixels", instead of the 'at minimum 3' claimed by MS).» Turner further explains his view: However, the method Gibson describes can also be viewed as a limitation of the way the machine generates color, rather than as a technique intentionally exploited by programmers to increase resolution. It is sometimes claimed (such as by Steve Gibson ) that the Apple II, introduced in 1977, supports an early form of subpixel rendering in its high-resolution (280×192) graphics mode. ( August 2014) ( Learn how and when to remove this template message) Statements consisting only of original research should be removed. Please improve it by verifying the claims made and adding inline citations. This section possibly contains original research.
PIXEL CHECK MAC OS MAC OS X
Any other filter will either be blurrier or will introduce color artifacts.Īpple was able to use it in Mac OS X due to a patent cross-licensing agreement. Microsoft's patent describes the smallest filter possible that distributes each subpixel value to an equal amount of R,G, and B pixels. Analysis by FreeType of the patent indicates that the idea of subpixel rendering is not covered by the patent, but the actual filter used as a last step to balance the color is. Microsoft has several patents in the United States on subpixel rendering technology for text rendering on RGB Stripe layouts. Apple, then IBM, and finally Microsoft patented various implementations with certain technical differences owing to the different purposes their technologies were intended for. The origin of subpixel rendering as used today remains controversial.
Text usually appears a solid colour on-screen because the red, green, and blue light are combined, and results in an indistinguishable appearance to the human eye.
Pixels on an LCD are made up of separate red, green, and blue elements, which can be utilized for finer control over rendering the curvature of text. For example, if the display uses triangularly-arranged subpixels, subpixel rendering that assumes RGB stripes will produce color fringing at the edges of text. If the subpixel rendering algorithm does not take into account a display's unconventional primary colors like in an RGBW LCD or an RGBW organic light emitting diodes (OLED) display, or unconventional subpixel locations like in a display that uses R, G, and B primaries placed in a triangular arrangement instead of using RGB stripes, subpixel rendering can fail. In a CRT it would require the designer to know precisely where each pixel hits the display's aperture grille, alignment variations that are part of the production process, and variation in the beam steering electronics, make this virtually impossible. The technique usually has good application to RGB LCDs and other display technologies that organize subpixels in a similar way. The technique needs to be matched to the panel that it is being applied on to work. Subpixel rendering is better suited to some display technologies than others. Over a certain resolution threshold the colors in the subpixels are not visible, but the relative intensity of the components shifts the apparent position or orientation of a line. The components are easily visible, however, when viewed with a small magnifying glass, such as a loupe. These pixel components, sometimes called subpixels, appear as a single color to the human eye because of blurring by the optics and spatial integration by nerve cells in the eye. Some displays have more than three primaries, such as the combination of red, green, blue, and yellow (RGBY) or red, green, blue, and white (RGBW) or even red, green, blue, yellow, and cyan (RGBYC). The previous image, with the R, G and B channel separated and animated.Ī single pixel on a color subpixelated display is made of several color primaries, typically three colored elements-ordered (on various displays) either as blue, green, and red (BGR), or as red, green, and blue (RGB).
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