Source: http://www.google.com/patents/US7221381?dq=6978253
Timestamp: 2015-10-04 13:14:43
Document Index: 82522143

Matched Legal Cases: ['Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60']

Patent US7221381 - Methods and systems for sub-pixel rendering with gamma adjustment - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsThe gamma adjustment allows the luminance for the sub-pixel arrangement to match the non-linear gamma response of the human eye's luminance channel, while the chrominance can match the linear response of the human eye's chrominance channels. The gamma correction allows the algorithms to operate independently...http://www.google.com/patents/US7221381?utm_source=gb-gplus-sharePatent US7221381 - Methods and systems for sub-pixel rendering with gamma adjustmentAdvanced Patent SearchPublication numberUS7221381 B2Publication typeGrantApplication numberUS 10/150,355Publication dateMay 22, 2007Filing dateMay 17, 2002Priority dateMay 9, 2001Fee statusPaidAlso published asCN1539129A, CN1539129B, EP1417666A2, EP2378506A2, EP2378506A3, US7623141, US7755649, US7911487, US8159511, US8830275, US20030103058, US20070182756, US20070206013, US20070285442, US20100026709, US20110157217, WO2003015066A2, WO2003015066A3Publication number10150355, 150355, US 7221381 B2, US 7221381B2, US-B2-7221381, US7221381 B2, US7221381B2InventorsCandice Hellen Brown Elliott, Seok Jin Han, Moon Hwan Im, In Chul Baek, Michael Francis Higgins, Paul HigginsOriginal AssigneeClairvoyante, IncExport CitationBiBTeX, EndNote, RefManPatent Citations (102), Non-Patent Citations (48), Referenced by (31), Classifications (36), Legal Events (6) External Links: USPTO, USPTO Assignment, EspacenetMethods and systems for sub-pixel rendering with gamma adjustment
US 7221381 B2Abstract
The gamma adjustment allows the luminance for the sub-pixel arrangement to match the non-linear gamma response of the human eye's luminance channel, while the chrominance can match the linear response of the human eye's chrominance channels. The gamma correction allows the algorithms to operate independently of the actual gamma of a display device. The sub-pixel rendering techniques disclosed with gamma adjustment can be optimized for a display device gamma to improve response time, dot inversion balance, and contrast because gamma correction and compensation of the sub-pixel rendering algorithm provides the desired gamma through sub-pixel rendering. These techniques can adhere to any specified gamma transfer curve.
applying gamma adjustment to a conversion from the pixel data to sub-pixel rendered data, the conversion generating the sub-pixel rendered data for a sub-pixel arrangement including alternating red and green sub-pixels on at least one of a horizontal and vertical axis; wherein said step of applying gamma adjustment further comprises performing gamma correction on a local average based on the pixel data to produce a gamma-corrected local average, and converting the gamma-corrected local average multiplied by the pixel data to the sub-pixel rendered data; and
outputting the sub-pixel rendered data.
2. The method of claim 1, wherein the applying gamma adjustment includes:
performing omega correction on the pixel data to produce omega-corrected data; and
calculating an omega-corrected local average based on the omega-corrected data.
3. The method of claim 2, wherein the applying gamma adjustment further includes:
performing gamma correction on the omega-corrected local average to produce a gamma-with-omega-corrected local average; and
converting the gamma-with-omega-corrected local average multiplied by the pixel data to the sub-pixel rendered data.
a receiving module to receive pixel data;
a processing module to perform a conversion from the pixel data to sub-pixel rendered data and to apply gamma adjustment to the conversion, the conversion generating the sub-pixel rendered data for a sub-pixel arrangement including alternating red and green sub-pixels on at least one of a horizontal and vertical axis; and
wherein further the processing module is to perform gamma correction on a local average to produce a gamma-corrected local average, and the processing module is to convert the gamma-corrected local average multiplied by the pixel data to the sub-pixel rendered data.
5. A system for processing data for a display including pixels, each pixel having color sub-pixels, the system comprising:
wherein the processing module is to perform omega correction on the pixel data to produce omega-corrected data and to calculate an omega-corrected local average based on the omega-corrected data.
6. The system of claim 5, wherein the processing module is to perform gamma correction on the omega-corrected local average to produce a gamma-with-omega-corrected local average and to convert the gamma-with-omega-corrected local average multiplied by the pixel data to the sub-pixel rendered data.
This application is a continuation-in-part and claims priority to now U.S. Pat. No. 7,123,277, entitled “CONVERSION OF A SUB-PIXEL FORMAT DATA TO ANOTHER SUB-PIXEL DATA FORMAT,” filed on Jan. 16, 2002, which is hereby expressly incorporated herein by reference. This application also claims priority to U.S. Provisional Patent Application No. 60/311,138, entitled “IMPROVED GAMMA TABLES,” filed on Aug. 8, 2001; U.S. Provisional Patent Application No. 60/312,955, entitled “CLOCKING BLACK PIXELS FOR EDGES,” filed on Aug. 15, 2001; U.S. Provisional Application No. 60/312,946, entitled “HARDWARE RENDERING FOR PENTILE STRUCTURES,” filed on Aug. 15, 2001; U.S. Provisional Application No. 60/314,622, entitled “SHARPENING SUB-PIXEL FILTER,” filed on Aug. 23, 2001; and U.S. Provisional Patent Application No. 60/318,129, entitled “HIGH SPEED MATHEMATICAL FUNCTION EVALUATOR,” filed on Sep. 7, 2001, which are all hereby expressly incorporated herein by reference.
The '992 application claims priority to U.S. Provisional Patent Application No. 60/290,086, entitled “CONVERSION OF RGB PIXEL FORMAT DATA TO PENTILE MATRIX SUB-PIXEL DATA FORMAT,” filed on May 9, 2001; U.S. Provisional Patent Application No. 60/290,087, entitled “CALCULATING FILTER KERNEL VALUES FOR DIFFERENT SCALED MODES,” filed on May 9, 2001; U.S. Provisional Patent Application No. 60/290,143, entitled “SCALING SUB-PIXEL RENDERING ON PENTILE MATRIX,” filed on May 9, 2001; and U.S. Provisional Patent Application No. 60/313,054, entitled “RGB STRIPE SUB-PIXEL RENDERING DETECTION,” filed on Aug. 16, 2001, which are all hereby expressly incorporated herein by reference.
Martinez-Uriegas, et al. in U.S. Pat. No. 5,398,066 and Peters, et al. in U.S. Pat. No. 5,541,653 teach a technique to convert and store images from RGB pixel format to a format that is very much like that taught by Bayer in U.S. Pat. No. 3,971,065 for a color filter array for imaging devices for cameras. The advantage of the Martinez-Uriegas, et al. format is that it both captures and stores the individual color component data with similar spatial sampling frequencies as human vision. However, a first disadvantage is that the Martinez-Uriegas, et al. format is not a good match for practical color display panels.
For this reason, Martinez-Uriegas, et al. also teach how to convert the image back into RGB pixel format. Another disadvantage of the Martinez-Uriegas, et al. format is that one of the color components, in this case the red, is not regularly sampled. There are missing samples in the array, reducing the accuracy of the construction of the image when displayed.
Color perception is influenced by a process called “assimilation” or the Von Bezold color blending effect. This is what allows separate color pixels (or sub-pixels or emitters) of a display to be perceived as the mixed color. This blending effect happens over a given angular distance in the field of view. Because of the relatively scarce blue receptors, this blending happens over a greater angle for blue than for red or green. This distance is approximately 0.25� for blue, while for red or green it is approximately 0.12�. At a viewing distance of twelve inches, 0.25� subtends 50 mils (1,270 μ) on a display. Thus, if the blue sub-pixel pitch is less than half (625 μ) of this blending pitch, the colors will blend without loss of picture quality.
If the color of the image were to be ignored, then each sub-pixel may serve as a though it were a monochrome pixel, each equal. However, as color is nearly always important (and why else would one use a color display?), then color balance of a given image is important at each location. Thus, the sub-pixel rendering algorithm must maintain color balance by ensuring that high spatial frequency information in the luminance component of the image to be rendered does not alias with the color sub-pixels to introduce color errors.
The approaches taken by Benzchawel, et al. in U.S. Pat. No. 5,341,153, and Hill, et al. in U.S. Pat. No. 6,188,385, are similar to a common anti-aliasing technique that applies displaced decimation filters to each separate color component of a higher resolution virtual image. This ensures that the luminance information does not alias within each color channel.
The prior art arrangements of three-color pixel elements are shown to be both a poor match to human vision and to the generalized technique of sub-pixel rendering.
Likewise, the prior art image formats and conversion methods are a poor match to both human vision and practicable color emitter arrangements.
Another complexity for sub-pixel rendering is handling the non-linear response (e.g., a gamma curve) of brightness or luminance for the human eye and display devices such as a cathode ray tube (CRT) device or a liquid crystal display (LCD).
Compensating gamma for sub-pixel rendering, however, is not a trivial process. That is, it can be problematic to provide the high contrast and right color balance for sub-pixel rendered images. Furthermore, prior art sub-pixel rendering systems do not adequately provide precise control of gamma to provide high quality images.
Consistent with the invention, one method is disclosed for processing data to a display. The display includes pixels having color sub-pixels. Pixel data is received and gamma adjustment is applied to a conversion from the pixel data to sub-pixel rendered data. The conversion generates the sub-pixel rendered data for a sub-pixel arrangement . The sub-pixel arrangement includes alternating red and green sub-pixels on at least one of a horizontal and vertical axis. The sub-pixel rendered data is outputted to the display.
Consistent with the invention, one system is disclosed having a display with a plurality of pixels. The pixels can have a sub-pixel arrangement including alternating red and green sub-pixels in at least one of a horizontal axis and vertical axis. The system also includes a controller coupled to the display and processes pixel data. The controller also applies a gamma adjustment to a conversion from the pixel data to sub-pixel rendered data.
The conversion can generate the sub-pixel rendered data for the sub-pixel arrangement. The controller outputs the sub-pixel rendered data on the display.
FIG. 17 illustrates the array of sample points and their effective sample areas of prior art FIG. 15 overlaid on the blue color plane sampling areas of FIG. 12, in which the sample points of prior art FIG. 15 are on the same spatial resolution grid and coincident with the red and green “checker board” array of FIG. 11;
FIG. 24 illustrates the array of sample points and their effective sample areas of prior art FIG. 21 overlaid on the blue color plane sampling areas of FIG. 8, in which the sample points of prior art FIG. 21 are not on the same spatial resolution grid nor coincident with the red and green “checker board” array of FIG. 7;
FIG. 1 illustrates a prior art RGB stripe arrangement of three-color pixel elements in an array, a single plane, for a display device and FIG. 2 illustrates the effective sub-pixel rendering sampling points for the prior art RGB stripe arrangement of FIG. 1.
FIGS. 3, 4, and 5 illustrate the effective sub-pixel rendering sampling area for each color plane of the sampling points for the prior art RGB stripe arrangement of FIG. 1. FIGS. 1-5 will be discussed further herein.
FIG. 6 illustrates an arrangement 20 of several three-color pixel elements according to one embodiment. The three-color pixel element 21 is square-shaped and disposed at the origin of an X, Y coordinate system and comprises a blue emitter 22, two red emitt