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Researchers Submit Patent Application, "A Method of Processing Image Data for Display on a Display Device, Which Comprising a Multi-Primary Image...

August 20, 2014



Researchers Submit Patent Application, "A Method of Processing Image Data for Display on a Display Device, Which Comprising a Multi-Primary Image Display Panel", for Approval

By a News Reporter-Staff News Editor at Electronics Newsweekly -- From Washington, D.C., VerticalNews journalists report that a patent application by the inventors Broughton, Benjamin John (Oxford, GB); Borgers, Charlotte Wendy Michele (Huntingdon, GB); Gass, Paul Antony (Oxford, GB); Boham, Scott (Cambridge, GB); Maeda, Kenji (Osaka, JP); Watanabe, Tatsuo (Osaka, JP), filed on October 25, 2012, was made available online on August 7, 2014.

The patent's assignee is Sharp Kabushiki Kaisha.

News editors obtained the following quote from the background information supplied by the inventors: "Multiprimary displays, consisting of at least four different colour sub-pixels, have been developed and produced in several different types, with several different performance aims.

"Displays using more than the standard three (usually red, green and blue (RGB)) primaries for expansion of the range of displayable colours have been produced (Proceedings of the IDW'09, 2009, pp 1199-1202), as well as RGBW displays with an added white sub-pixel to improve display brightness and therefore efficiency (SID'08 Digest, pp 1112-1115). Multiprimary displays have also been produced with the aim of simultaneously increasing brightness, as well as increasing the ability to render fine image features on a sub-pixel level (IMID '05 Digest, pp 867-872). Displays with an additional yellow sub-pixel (RGBY) have also been developed possessing enhanced brightness, increased colour gamut, and increased sub-pixel rendering ability (SID'10 Digest, pp 281-282). As multiprimary displays have more than three types of colour sub-pixel, for many colour and luminance values, there may be multiple configurations of individual data values supplied to the colour sub-pixels which produce the target colour. The multiple configurations producing the same overall luminance and chromaticity are known as metamers. Selection of which of a set of possible metamers to use for a particular pixel in an image, based on sub-pixel rendering considerations, is described in US2010 0277498.

"Several types of display which switchable between a public and private display mode, with varying degrees of additional cost over a standard display, ease of use and strength of privacy performance are also well known.

"Devices incorporating such displays include mobile phones, Personal Digital Assistants (PDAs), laptop computers, desktop monitors, Automatic Teller Machines (ATMs) and Electronic Point of Sale (EPOS) equipment. Such devices can also be beneficial in situations where it is distracting and therefore unsafe for certain viewers (for example drivers or those operating heavy machinery) to be able to see certain images at certain times, for example an in car television screen while the car is in motion.

"Several methods exist for adding a light controlling apparatus to a naturally wide-viewing range display, such as a microlouvre film (USRE27617 (F. O. Olsen; 3M 1973), U.S. Pat. No. 4,766,023 (S.-L. Lu, 3M 1988), and U.S. Pat. No. 4,764,410 (R. F. Grzywinski; 3M 1988)). However, this and other methods involving detachable optical arrangements are not conveniently switchable, requiring as they do manual placement and removal of the film or other apparatus to change the display from the public to the private mode.

"Methods of providing an electronically switchable privacy function are disclosed in GB2413394 (Sharp), W006132384A1 (Sharp, 2005) and GB2439961 (Sharp). In these inventions, a switchable privacy device is constructed by adding one or more extra liquid crystal layers and polarisers to a display panel. The intrinsic viewing angle dependence of these extra elements can be changed by switching the liquid crystal electrically in the well-known way. Devices utilising this technology include the Sharp Sh851i and Sh902i mobile phones. These methods share the disadvantages that the additional optical components add thickness and cost to the display.

"Methods to control the viewing angle properties of an LCD by switching the single liquid crystal layer of the display between two different configurations, both of which are capable of displaying a high quality image to the on-axis viewer are described in US20070040780A1 and GB 0721255.8. These devices provide the switchable privacy function without the need for added display thickness, but require complex pixel electrode designs and other manufacturing modifications to a standard display.

"One example of a display device with privacy mode capability with no added display hardware complexity is the Sharp Sh702iS mobile phone. This uses a manipulation of the image data displayed on the phone's LCD, in conjunction with the angular dataluminance properties inherent to the liquid crystal mode used in the display, to produce a private mode in which the displayed information is unintelligible to viewers observing the display from an off-centre position. A key advantage of this type of method is that in the public mode, the display consists of, and operates as, a standard display, with no image quality degradation causes by the private mode capability. However, when in the private mode, the quality of the image displayed to the legitimate, on-axis viewer is severely degraded.

"Improved schemes which, when in the private mode, manipulate the image data in a manner dependent on a second, masking, image, and therefore causes that masking image to be perceived by the off-axis viewer when the modified image is displayed, are given in GB2428152A1, W02009110128A1, W0201134209 and W0201134208. These methods provide an electronically switchable public/private display with no additional optical elements required, minimal additional cost, and satisfactory privacy performance. However, as the methods all utilise the limited resolution of the human visual system by representing the main and side images using the average luminance produced by groups of adjacent pixels. Therefore, a resolution loss in the image display to the On-axis viewer is incurred.

"It is therefore desirable to provide a high quality LCD display which has public and private mode capability, in which no modification to the LC layer or pixel electrode geometry is required from a standard display, has a substantially unaltered display performance (brightness, contrast resolution etc) in the public mode, and in the private mode has a strong privacy effect with minimal degradation to the on-axis image quality, particularly with regard to resolution loss incurred in the private mode."

As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventors' summary information for this patent application: "A first aspect of the invention provides a method of processing image data for display on a display device, the display device comprising a multi-primary image display panel, the method comprising: receiving image data constituting an image for display on the image display panel; and in a first mode, determining signal voltages to be applied to sub-pixels of the image display panel from the received pixel data and from a secondary data value for the pixel thereby to generate luminance variations perceivable at a first viewing position but substantially not perceivable at a second viewing position.

"This mode of operation of the display device provides a private (narrow-view) display mode for the multi-primary image display panel (which is a display panel having pixels or sub-pixels of more than the standard three primary colours such as, for example, an RGBW or RGBY image panel). The luminance variations generated as a result of the secondary data values serve to obscure the image that would be generated if the received image data were the sole input, so that a viewer at the first viewing position (for example position 5 in FIG. 2) which is outside the intended viewing range in the private mode (the narrow viewing range 6 in FIG. 2) cannot make out the image, or can only see a degraded version of the image, owing to the superposed luminance variations. A viewer at the second viewing position (for example position 3 in FIG. 2) which is inside the intended viewing range in the private mode perceives little or no luminance variations, and so sees the original image (that is, the image that would be generated if the received image data were the sole input) with little or no degradation in image quality.

"To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative embodiments of the invention. These embodiments are indicative, however, of but a few of the various ways in which the principles of the invention may be employed. Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the drawings.

BRIEF DESCRIPTION OF DRAWINGS

"In the annexed drawings, like references indicate like parts or features:

"FIG. 1: is an example schematic of a standard LCD display panel and associated control electronics.

"FIG. 2: is a schematic of a display with a switchable public/private viewing mode, according to an embodiment of the present invention.

"FIG. 3: is a schematic illustrating how a portion of the control electronics of the prior art for an RGB type display may be implemented in an electronic circuit.

"FIG. 4: is a schematic illustrating how a portion of the control electronics of an embodiment for an RGBW type display may be implemented in an electronic circuit.

"FIG. 5: is a diagram illustrating the pattern of pixel data modifications applied in a method of the prior art, and the resulting image resolution loss.

"FIG. 6: is a diagram illustrating the pattern of pixel data modifications of an embodiment of the present invention, showing no resolution loss resulting from the modifications.

"FIG. 7: is a diagram illustrating the pattern of pixel data modifications applied to a coloured input data in a method of the prior art, and the resulting image resolution loss.

"FIG. 8: is a diagram illustrating the pattern of pixel data modifications of an embodiment of the present invention applied to a coloured input data, showing reduced resolution loss resulting from the modifications.

"FIG. 9: is a diagram illustrating the pattern of pixel data modifications of an embodiment of the present invention applicable to RGBY type multiprimary displays, showing reduced resolution loss resulting from the modifications.

"FIG. 10: is a diagram illustrating the pattern of pixel data modifications of an embodiment of the present invention applied an RGBY type multiprimary display with coloured input data.

"FIG. 11: is a diagram illustrating the pattern of pixel data modifications of an embodiment of the present invention applied to an RGBY type multiprimary display with coloured input data, showing reduced resolution loss resulting from the modifications.

"FIG. 12: is a diagram illustrating the pattern of pixel data modifications of an embodiment of the present invention applied to an RGBY type multiprimary display showing no luminance resolution loss resulting from the modifications, but some chrominance resolution loss.

"FIG. 13: is a process flow diagram illustrating a possible implementation of embodiments of the present invention.

"FIG. 14: is a process flow diagram illustrating two possible implementations of an embodiment of the present invention.

"FIG. 15: is a diagram illustrating the pattern of pixel data modifications of an embodiment of the present invention applied to a Pentile type display.

"FIG. 16: is a diagram illustrating the pattern of pixel data modifications of an embodiment of the present invention applied to a Pentile type display with high spatial frequency input data.

"FIG. 17: is a diagram illustrating the pattern of pixel data modifications of a further embodiment of the present invention applied to a Pentile type display.

"FIG. 18: is a diagram illustrating the pattern of pixel data modifications of a further embodiment of the present invention applied to a Pentile type display with high spatial frequency input data.

"FIG. 19: is a diagram illustrating the pattern of pixel data modifications of a further embodiment of the present invention applied to a Pentile type display with high spatial frequency input data.

"FIG. 20: is a diagram illustrating the pattern of pixel data modifications of a still further embodiment of the present invention applied to a Pentile type display.

"FIG. 21: is a diagram illustrating the pattern of pixel data modifications of a still further embodiment of the present invention applied to a Pentile type display with high spatial frequency input data.

"FIG. 22: is a diagram illustrating the pattern of pixel data modifications of a still further embodiment of the present invention applied to a Pentile type display, with uniform, and high spatial frequency input data."

For additional information on this patent application, see: Broughton, Benjamin John; Borgers, Charlotte Wendy Michele; Gass, Paul Antony; Boham, Scott; Maeda, Kenji; Watanabe, Tatsuo. A Method of Processing Image Data for Display on a Display Device, Which Comprising a Multi-Primary Image Display Panel. Filed October 25, 2012 and posted August 7, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=4794&p=96&f=G&l=50&d=PG01&S1=20140731.PD.&OS=PD/20140731&RS=PD/20140731

Keywords for this news article include: Electronics, Sharp Kabushiki Kaisha.

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Source: Electronics Newsweekly


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