Patent
Method and system for color point calibration of light source projector
| العنوان: | Method and system for color point calibration of light source projector |
|---|---|
| Patent Number: | 12164,218 |
| تاريخ النشر: | December 10, 2024 |
| Appl. No: | 17/615015 |
| Application Filed: | June 02, 2020 |
| مستخلص: | The present invention relates to image projection and provides a method and system for performing color calibration of light sources and correction towards a color target, for example a whitepoint target. The calibration and correction considers the ambient temperature and that the projector output has an arbitrary dimming level. The correction can be made automatic and can be performed by an operator in the field by pressing a button. |
| Inventors: | BARCO N.V. (Kortrijk, BE) |
| Assignees: | BARCO N.V. (Kortrijk, BE) |
| Claim: | 1. A method for correcting driving currents to reach a color point target for a multiple of primary colour light sources in an imaging system having a light source controller, the method comprising the steps of: defining a color point target, obtaining a measured ambient temperature, obtaining tristimulus values of the light from the primary colour light sources, providing initial driving current values which are incoming driving current values of the light sources to the light source controller, wherein the initial driving current values are provided for a reference ambient temperature, for each of the light sources: calculating driving current values for the light sources as a function of at least one of the tristimulus values of the light sources, at the reference ambient temperature, adapting the driving current values based on the difference between the measured ambient temperature and the reference ambient temperature, correcting the driving current values with alpha factors, wherein the alpha factors are the dimming levels for each light source for reaching the color point target, and which depend on a relation between the obtained tristimulus values and the color point target, and the function of the at least one of the tristimulus values, and applying corrected driving current values which are outgoing driving current values to the primary colour light sources. |
| Claim: | 2. The method of claim 1 , wherein a slider setting is used to set a light output value or a dimming level to a level between 1 and 100%. |
| Claim: | 3. The method of claim 2 , further comprising driving the light sources with currents related to the slider setting. |
| Claim: | 4. The method of claim 1 , wherein, for a displayed image, an external image sensor detects tristimulus values of the displayed image. |
| Claim: | 5. The method of claim 4 , wherein expressions for the driving current values for primary colour (RGB) driving current values are defined and fitted to the measured tristimulus values. |
| Claim: | 6. The method of claim 5 in which the primary colour (RGB) driving current values are fitted as follows: establishing a polynomial expression for the driving currents, wherein the polynomial expression is optionally of the second degree (I[red], I[green] and I[blue]), and fitting the polynomials to the measured tristimulus values, Xr, Yg and Zb, i.e. Ired to Xr, Ig to Yg and Ib to Zb and updating LUT values with the fitted curves. |
| Claim: | 7. The method of claim 1 , wherein the driving current at a temperature T[1] is obtained by multiplying a reference driving current at the reference ambient temperature, with a scaling factor for the driving current at the temperature T[1]. |
| Claim: | 8. The method of claim 5 , wherein a fitted driving current curve for the light sources of the same color differs from a neighbouring driving current curve for the light sources of another color, with a constant scaling value. |
| Claim: | 9. The method of claim 7 , wherein, if input driving currents to output behaviour of a light source at a reference temperature T[ref] are known and described by a LUT, and a scaling factor for temperature T[1] is established, the behaviour at temperature T[1] can be corrected by multiplying the LUT values with the scaling factor of a scaling factor function for temperature T[1]. |
| Claim: | 10. The method of claim 9 , wherein the same scaling factor function is used for the driving currents for all light sources of the same color so that scaling factor values are applied to the values of the LUT. |
| Claim: | 11. A method for carrying out a factory calibration, the calibration method comprising: LUT values obtainable from the outcome of method steps defined in claim 6 are selected as initial values for performing a factory calibration. |
| Claim: | 12. The method of claim 11 , wherein a slider setting is set a light output level or a dimming level to a first value, between 0 and 100%, and a reference temperature T[ref1] of an initial characterization is chosen from the range 5° to 50° C. |
| Claim: | 13. The method of claim 12 , wherein a LUT[ref1] is uploaded to the light source controller, wherein the LUT[ref1] is valid for the reference temperature T[ref1]. |
| Claim: | 14. The method of claim 13 , wherein a temperature T[m] is measured. |
| Claim: | 15. The method of claim 14 , wherein a driving current from LUT[ref1] is corrected with a scaling factor for temperature T[m]. |
| Claim: | 16. A method comprising a field calibration or a field re-calibration, the method optionally comprising the method of claim 1 . |
| Claim: | 17. The method of claim 16 , wherein for a re-calibration of a projector in the field, an internal color sensor of the projector is used to determine values for LUTs for different lasers. |
| Claim: | 18. A non-transitory machine readable signal storage means storing a computer program product comprising software which, when executed on a processor implements the method of claim 1 . |
| Claim: | 19. A system for correcting laser driving currents to reach a color point target for a multiple of primary colour light sources in an imaging system having a light source controller, comprising: means for defining a color point target, means for receiving a measured ambient temperature, means for receiving tristimulus values of the light from the primary colour light sources, means for providing initial laser driving current values, which are incoming laser driving current values of the light sources to the light source controller, wherein the initial laser driving current values are provided for a reference ambient temperature, and for each of the light sources: means for obtaining current conversion values between incoming laser driving currents and outgoing laser driving currents; wherein the light sources are adapted to receive the outgoing laser driving currents, means for calculating the outgoing laser driving current values for the light sources as a function of at least one of the tristimulus values of the light sources, at the reference ambient temperature based on the incoming laser driving current values, means for adapting the laser driving current values based on the difference between the measured ambient temperature and the reference ambient temperature, means for correcting the laser driving current values with alpha factors, wherein the alpha factors are the dimming levels for each light source for reaching the color point target, and which depend on a relation between the obtained tristimulus values and the color point target, and the function of the at least one of the tristimulus values, and means for applying corrected laser driving current values as outgoing laser driving current values to the primary colour light sources. |
| Claim: | 20. A system for correcting driving currents to reach a color point target for a multiple of primary colour light sources in an imaging system having a light source controller, comprising: means for defining a color point target, means for receiving a measured ambient temperature, means for receiving tristimulus values of the light from the primary light sources, means for providing initial driving current values of the light sources to the light source controller, wherein the initial driving current values are provided for a reference ambient temperature, and for each of the light sources: means for calculating driving current values for the light sources as a function of at least one of the tristimulus values of the light sources, at the reference ambient temperature, means for adapting the driving current values based on the difference between the measured ambient temperature and the reference ambient temperature, means for correcting the driving current values with alpha factors, wherein the alpha factors are the dimming levels for each light source for reaching the color point target, and which depend on a relation between the obtained tristimulus values and the color point target, and the function of the at least one of the tristimulus values, and means for applying corrected driving current values to the primary light sources, and further comprising a projector adapted so that any dependencies on the ambient temperature are controlled using an internal light sensor. |
| Patent References Cited: | 8382287 February 2013 Keh 8605764 December 2013 Rothaar et al. 20030179211 September 2003 Wada et al. 20070103646 May 2007 Young 20120062849 March 2012 Kuo et al. 20140035465 February 2014 Raj et al. 20140118424 May 2014 Young et al. 20150380898 December 2015 Okamoto et al. 1447217 October 2003 101738831 June 2010 |
| Other References: | International Search Report and Written Opinion issued in PCT/EP2020/065246, dated Oct. 1, 2020. cited by applicant International Search Report and Written Opinion issued in PCT/EP2019/064245, dated Feb. 28, 2020. cited by applicant Office Action issued in Chinese Application No. 202080053419.7, dated Jul. 22, 2023, with English translation. cited by applicant |
| Primary Examiner: | Brooks, Jerry L |
| Attorney, Agent or Firm: | HSML P.C. |
| رقم الانضمام: | edspgr.12164218 |
| قاعدة البيانات: | USPTO Patent Grants |
| الوصف غير متاح. |