Method and Device for Improving Spatial and Off-Axis Display Standard Conformance

• US 20070236517A1
• Filed: 04/15/2004
• Published: 10/11/2007
• Est. Priority Date: 04/15/2004
• Status: Active Grant

• Current Assignee: Barco NV
• Original Assignee: Barco NV
• Inventors: Kimpe, Tom
• Granted Patent: US 8,228,348 B2
• Time in Patent Office: Days
• US Class Current: 345/690
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0276 for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
• CPC Class Codes: G09G 2320/028 by changing the viewing angle properties, e.g. widening the viewing angle, adapting the viewing angle to the view direction
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 2320/0606 Manual adjustment
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2320/068 for control of viewing angle adjustment
• CPC Class Codes: G09G 2320/0693 Calibration of display systems
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 3/2092 Details of a display terminals using a flat panel, the details relating to the control arrangement of the display terminal and to the interfaces thereto suitable for both CRT and flat panel G09G5/003; specific for a CRT G09G1/165

Abstract

The invention describes a method for improving the spatial and off-axis conformance of display systems with respect to an enforced greyscale or colour display standard. In the display systems, the native transfer curve is obtained for each pixel or zone of pixels, i.e. as a function of position on the display and as a function of viewing-angle. Once that information is available, an optimal conversion scheme from P-value to DDL can be created for each position on the display and this for all possible viewing-angles. In use, the conversion scheme is used to obtain an improved DICOM behaviour. This optimisation is also done with respect to the viewing-angle, based on a pre-set, selectable or measured viewing angle.

Claims

1. A method for correcting non-conformance in greyscale or colour values of a plurality of zones of pixel elements in a matrix display, the correcting being with respect to an enforced greyscale or colour display standard, each zone of pixel elements being corrected by a different calibration function, the method comprising,

for each zone of pixel elements independently,

storing characterisation data characterising the non-conformance in greyscale or colour values of the zone of pixel elements as a function of its drive signals,

pre-correcting, in accordance with the characterisation data, the drive signals of said zone of pixel elements so as to obtain a greyscale or colour level conform said enforced greyscale or colour display standard, said pre-correcting being performed based on an input value of the greyscale or colour value to be displayed and the viewing angle under which the zone of pixel elements is or is to be viewed at,

wherein the method furthermore comprises adjusting the pre-correcting if the viewing angle under which the zone of pixel elements is or is to be viewed at, is outside a pre-determined range.

2. A method according to claim 1, wherein adjusting the pre-correcting comprises reducing the number of greyscale levels.

3. A method according to claim 2, wherein adjusting the pre-correcting comprises changing the display content to a uniform greyscale level.

4. A method according to any of the previous claims, wherein a zone of pixel elements consists of one pixel element.

5. A method according to any of claims 1 to 3, wherein a zone of pixel elements comprises a plurality of pixel elements, each pixel element of a zone being assigned a same characterisation data.

6. A method for correcting according to any of the previous claims, wherein said viewing angle under which the matrix display is or is to be viewed at is selectable by a user.

7. A method for correcting according to any of claims 1 to 5, wherein said viewing angle under which the matrix display is or is to be viewed at is measured using a detection system.

8. A method for correcting according to any of the previous claims, wherein said characterisation data furthermore comprises at least one of dependence on back-light intensity, dependence on an environmental parameter.

9. A method according to claim 8, wherein said environmental parameter is the intensity of environmental light.

10. A method for correcting according to any of claims 1 to 9, wherein said pre-correcting the drive signal is performed based on using a look-up table.

11. A method for correcting according to any of claims 1 to 10, wherein said pre-correcting the drive signal is performed at least partially based on using a mathematical function.

12. A method according to any of the previous claims, further comprising generating the characterisation data from images captured from individual zones of pixel elements.

13. A method according to claim 12, wherein generating the characterisation data comprises building a pixel element profile map representing characterisation data for each pixel element of the matrix display.

14. A method for correcting according to any of claims 1 to 13, wherein the pre-correcting is carried out in real-time during driving of the matrix display while displaying images.

15. A method for correcting according to any of claims 1 to 13, wherein the pre-correcting is carried out off-line at a time other than during driving of the matrix display while displaying images.

16. A method for correcting according to any of claims 1 to 15 wherein said enforced greyscale display standard is the Digital Imaging and Communications in Medicine (DICOM) standard published by National Electrical Manufacturers Association.

17. A system for correcting non-conformance in greyscale or colour values of a plurality of zones of pixel elements in a matrix display, the correcting being with respect to an enforced greyscale or colour display standard, the system comprising

a memory means for storing characterisation data characterising the non-conformance in greyscale or colour values of the plurality of zones of pixel elements as a function of its drive signals and as a function of a viewing angle under which the zone of pixel elements is to be viewed,

a correction device for pre-correcting, in accordance with the characterisation data, driving signals to the zone of pixel elements to obtain a greyscale or colour level conform the enforced greyscale or colour display standard, and adapted for adjusting those driving signals if the determined viewing angle is outside a pre-determined range.

18. A system according to claim 17, wherein the correction device is adapted for adjusting the driving signals to the zone of pixel elements so as to obtain a reduced number of greyscale or colour levels.

19. A system according to claim 18, wherein the correction device is adapted for adjusting the driving signals to the zone of pixel elements so as to obtain a single greyscale or colour level.

20. A system according to any of claims 17 to 19, furthermore comprising a characterising device for generating characterisation data for a number of zones of pixel elements by establishing a relationship between the greyscale or colour levels of each of said zones of pixel elements and the corresponding drive signal for a number of viewing angles and a number of spatial locations in the matrix display.

21. A system according to claim 20, wherein said characterising device comprises an image capturing device for generating an image of the pixel elements of the matrix display.

22. A system according to any of claims 17 to 21, wherein the correction device comprises a viewing angle determination device for determining the viewing angle of a user with respect to a display system.

23. A system according to any of claims 20 to 22, wherein the characterising device comprises a light-output value assigning device for assigning a native greyscale or colour luminance level as a function of its drive signals to a number of zones of pixel elements of the matrix display.

24. A matrix display device for displaying an image, the matrix display device comprising:

a plurality of zones of pixel elements,

a memory for storing characterisation data for a number of zones of pixel elements of the matrix display, the characterisation data representing a relationship between greyscale or colour levels of a zone of pixel elements and its corresponding drive signals, the characterisation data being a function of the spatial location of the zone of pixel elements in the matrix display and a function of the viewing angle under which the zone of pixel elements is or is to be viewed at,

a means for determining the viewing angle of a user with respect to the matrix display,

a correction device for pre-correcting, in accordance with the characterisation data, driving signals to the zones of pixel elements so as to obtain a greyscale or colour level conform an enforced greyscale or colour display standard, and adapted for adjusting those driving signals if the determined viewing angle is outside a pre-determined range.

25. A matrix display device according to claim 24, wherein the correction device is adapted for adjusting the driving signals so that only a reduced number of greyscale or colour levels is represented.

26. A matrix display device according to claim 25, wherein the correction device is adapted for adjusting the driving signals so that only a single greyscale or colour level is represented.

27. A control unit for use with a system for correction of non-conformance in greyscale or colour values of a plurality of zones of pixel elements of a matrix display for displaying an image, the correction being with respect to an enforced greyscale or colour display standard, the control unit comprising:

means for storing characterisation data for a number of zones of pixel elements of the matrix display, the characterisation data representing a relationship between greyscale or colour levels of a zone of pixel elements and its corresponding drive signals, the characterisation data being a function of the spatial location of the zone of pixel elements in the matrix display and a function of a viewing angle under which the zone of pixel elements is or is to be viewed at,

means for determining the viewing angle of a user with respect to the matrix display, and

means for pre-correcting, in accordance with the characterisation data, driving signals to the zone of pixel elements so as to obtain a greyscale or colour level conform the enforced greyscale or colour display standard, wherein the means for pre-correcting is adapted for adjusting the driving signals if the determined viewing angle is outside a pre-determined range.