Method for radiometric display, corresponding system, apparatus and computer program product

Patent metadata

Field	Value
Publication number	US-11037522-B2
Application number	US-201816047768-A
Country	US
Kind code	B2
Filing date	Jul 27, 2018
Priority date	Dec 24, 2014
Publication date	Jun 15, 2021
Grant date	Jun 15, 2021

Abstract

Color signals to be displayed on a colored display surface and having a first gamut in a color space, are subjected to radiometric compensation. An embodiment includes displaying on the colored surface a set of control points of a known color, acquiring via a camera the control points as displayed on the colored surface and evaluating at least one second color gamut of the control points displayed on the colored surface. The second color gamut(s) is/are misaligned with respect to the first color gamut due to the display surface being a colored surface. The method may also include evaluating as an intersection gamut, the misalignment of the second color gamut(s) with respect to the first color gamut, calculating the color transformation operator(s) as a function of the misalignment evaluated, and applying the color transformation operator(s) to the color signals for display on the colored display surface.

First claim

What is claimed is:

1. A radiometric compensation method for displaying, on a colored display surface, color signals having a first color gamut in a color space, the method comprising:
displaying, on the colored display surface, a set of control points of a known color, the color signals having the first color gamut in the color space, wherein the colored display surface is a uniformly colored display surface;
acquiring the set of control points as displayed on the colored display surface, wherein the set of control points displayed on the colored display surface as acquired have a single second color gamut in the color space, the second color gamut being misaligned with respect to the first color gamut;
evaluating the misalignment of the single second color gamut with respect to the first color gamut;
calculating a single color transformation operator as a function of the misalignment; and
applying the single color transformation operator to the color signals for all pixels of the display on the uniformly colored display surface.

2. The method of claim 1 , further comprising displaying on the colored display surface the color signals to which the single color transformation operator has been applied.

3. The method of claim 1 , wherein evaluating the misalignment of the single second color gamut and calculating the single color transformation operator comprises:
evaluating the misalignment of the single second color gamut with respect to the first color gamut as an intersection gamut therebetween; and
calculating the single color transformation operator as a mapping operator mapping the first color gamut to the intersection gamut.

4. The method of claim 3 , further comprising performing a boosting action of the color signals by allowing clipping at the intersection gamut.

5. The method of claim 1 , wherein calculating the single color transformation operator as the function of the misalignment comprises:
generating a set of lines joining the set of control points to a standard predetermined color;
sampling each line in the set from the standard predetermined color by finding a point common to the first color gamut and the single second color gamut displayable on the uniformly colored display surface; and
calculating the single color transformation operator as a transformation matrix from the set of control points to the common points found.

6. The method of claim 1 , further comprising:
converting the color signals for display on the uniformly colored display surface to a device-independent XYZ color space;
subjecting the color signals converted to the device-independent color space to the radiometric compensation as a function of the single color transformation operator; and
converting the color signals subjected to the radiometric compensation to conversion from the device-independent color space to a display color space for display on the uniformly colored display surface.

7. A radiometric compensation method for displaying, on a colored display surface, color signals having a first color gamut in a color space, the method comprising:
displaying on the colored display surface a set of control points of a known color, wherein the colored display surface is a uniformly colored display surface;
acquiring the set of control points as displayed on the colored display surface, wherein the set of control points displayed on the colored display surface as acquired have a single second color gamut in the color space, the second color gamut being misaligned with respect to the first color gamut;
evaluating the misalignment of the single second color gamut with respect to the first color gamut;
calculating a single color transformation operator as a function of the misalignment;
applying the single color transformation operator to the color signals of all pixels for display on the uniformly colored display surface; and
converting the color signals for display on the uniformly colored display surface to a perceptually uniform color space as a workspace for the radiometric compensation;
subjecting the color signals converted to the perceptually uniform color space to the radiometric compensation as a function of the single color transformation operator; and
converting the color signals subjected to the radiometric compensation to conversion from the perceptually uniform color space to a display color space for display on the uniformly colored display surface.

8. The method of claim 7 , further comprising displaying on the colored display surface the color signals to which the single color transformation operator has been applied.

9. The method of claim 7 , wherein evaluating the misalignment of the single second color gamut and calculating the single color transformation operator comprises:
evaluating the misalignment of the single second color gamut with respect to the first color gamut as an intersection gamut therebetween; and
calculating the single color transformation operator as a mapping operator mapping the first color gamut to the intersection gamut.

10. The method of claim 9 , further comprising performing a boosting action of the color signals by allowing clipping at the intersection gamut.

11. The method of claim 7 , further comprising:
generating a set of lines joining the set of control points to a middle grey color;
sampling each line in the set from the middle grey color by finding a point common to the first color gamut and the single second color gamut displayable on the uniformly colored display surface; and
calculating the single color transformation operator as a transformation matrix from the set of control points to the common points found.

12. The method of claim 7 , further comprising:
converting the color signals for display on the uniformly colored display surface to a device-independent XYZ color space;
subjecting the color signals converted to the device-independent color space to the radiometric compensation as a function of the single color transformation operator; and
converting the color signals subjected to the radiometric compensation to conversion from the device-independent color space to a display color space for display on the uniformly colored display surface.

13. A radiometric compensation method for displaying, on a colored display surface, color signals having a first color gamut in a color space, the method comprising:
displaying, on the colored display surface, a set of control points of a known color, wherein the colored display surface is a colored display surface having a display surface of a single color;
acquiring the set of control points as displayed on the colored display surface, wherein the set of control points displayed on the colored display surface as acquired have a single second color gamut in the color space, the second color gamut being misaligned with respect to the first color gamut;
evaluating the misalignment of the single second color gamut with respect to the first color gamut;
calculating a single color transformation operator as a function of the misalignment;
applying the single color transformation operator to the color signals for display on the colored display surface;
generating a set of lines joining the set of control points to a middle grey color;
sampling each line in the set from the middle grey color by finding a point common to the first color gamut and the single second color gamut displayable on the colored display surface; and
calculating the single color transformation operator as a transformation matrix from the set of control points to the common points found.

14. The method of claim 13 , further comprising di

Assignees

• St Microelectronics Srl

Inventors

• Naccari Filippo
• Guarnera Mirko
• Bianco Simone
• Schettini Raimondo

Classifications

• G09G3/002 Primary

  to project the image of a two-dimensional display, such as an array of light emitting or modulating elements or a CRT · CPC title

• H04N23/85

  for matrixing · CPC title

• H04N9/3194

  including sensor feedback · CPC title

• H04N9/3182

  Colour adjustment, e.g. white balance, shading or gamut (white balance per se H04N9/73; control of amplitude of colour signals H04N9/68; colour control circuits for displays in general G09G5/02, G09G3/2003, G09G3/3607) · CPC title

• H04N1/6097

  depending on the characteristics of the output medium, e.g. glossy paper, matt paper, transparency or fabrics · CPC title