Multi-primary conversion

• US 8,248,430 B2
• Filed: 10/17/2007
• Issued: 08/21/2012
• Est. Priority Date: 10/19/2006
• Status: Active Grant

• Current Assignee: Top Victory Investments Limited (TPV Technology Co., Ltd. (f/k/a Nanjing Huadong Electronics Information & Technology))
• Original Assignee: TP Vision Holding BV (TPV Technology Co., Ltd. (f/k/a Nanjing Huadong Electronics Information & Technology))
• Inventors: Hekstra, Gerben Johan, Klompenhouwer, Michiel Adriaanszoon
• Primary Examiner(s): Tung, Kee M
• Assistant Examiner(s): Wu, Sing-Wai
• Application Number:
  US12/445,476
• Publication Number:
  US 20100013848A1
• Time in Patent Office: 1,770 Days
• Field of Search: None
• US Class Current: 345/589
• CPC Class Codes: G09G 2340/0457 Improvement of perceived resolution by subpixel rendering
• CPC Class Codes: G09G 2340/06 Colour space transformation
• CPC Class Codes: G09G 3/20 for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
• CPC Class Codes: G09G 3/3607 for displaying colours or for displaying grey scales with a specific pixel layout, e.g. using sub-pixels display of colours in flat matrix panels other than liquid crystal displays G09G3/2003; grey scales specific for television H04N3/127

Abstract

A method converts an input image signal (IS) into a drive signal (DS) for driving sub-pixels (SP) of a display device (DD) comprising display pixels (DPI) having at least two sub-pixel groups (SG1, SG2) being able to contribute to luminance information displayed. The conversion comprises a multi-primary conversion (MPC) which receives the input image signal (IS) and which is performed under a constraint (CO). The constraint (CO) is determined (CD) by substantially matching local display luminances (DL1, DL2; DLD) associated with the at least two sub-pixel groups (SG1, SG2) with corresponding local input luminances (L1, L2; LD) of input pixels (IP) of the input image signal (IS), thereby obtaining a display luminance pattern defined by the display pixels (DPI) corresponding to an input luminance pattern defined by the input pixels (IP) associated with the display pixels (DPI).

Claims

1. A method of converting an input image signal into a drive signal for driving sub-pixels of a display device comprising display pixels having at least two sub-pixel groups being able to contribute to luminance information displayed, the conversion comprising:

a multi-primary conversion for receiving the input image signal and being performed under a constraint, and

first determining the constraint by substantially matching local display luminances associated with the at least two sub-pixel groups with corresponding local input luminances of input pixels of the input image signal, thereby obtaining a display luminance pattern defined by the display pixels corresponding to an input luminance pattern defined by the input pixels associated with the display pixels; and

,

wherein the first determining the constraint comprises;

selecting a first display area comprising a first sub-pixel group and a second sub-pixel group of the at least two sub-pixel groups, and a second display area comprising the first sub-pixel group and being a sub-area of the first display area,

computing a first input luminance for input pixels associated with the first display area,

computing a second input luminance for input pixels associated with the second display area, and

second determining the constraint to obtain a substantially matching ratio or difference between on the one hand the first input luminance and the second input luminance and on the other hand a first display luminance being the luminance of the sub-pixels covered by the first display area and a second display luminance being the luminance of the sub-pixels covered by the second display area.

2. A method as claimed in claim 1, wherein the first display area covers sub-pixels of all types to allow reproduction of any desired color.

3. A method as claimed in claim 1, wherein the determining the constraint adds an equation to the multi-primary conversion defining the ratio or difference between the first display luminance and the second display luminance substantially matching the ratio or difference, respectively, of the first input luminance and the second input luminance.

4. A method as claimed in claim 1, further comprising a matrix multiplication for multiplying the input signal with a matrix to obtain an output signal of the multi-primary conversion, the matrix being defined by the coordinates of primaries associated with the sub-pixels and the sub-pixel pattern of the display and including the constraint.

5. A method as claimed in claim 1, further comprising

determining local input luminances associated with sub-pixels covered by a sub-pixel region including and surrounding a particular one of the sub-pixels having a particular color to Obtain an output signal of the multi-primary conversion,

distributing the output image signal of the multi-primary, conversion of the sub-pixel over the sub-pixels of the sub-pixel region to obtain a distributed image signal, the distributing being performed in accordance with the local input luminances associated with the sub-pixels covered by the sub-pixel region, to obtain a luminance distribution across the sub-pixels corresponding to the luminance distribution of the local input luminances, and

accumulating the distributed image signal per sub-pixel for all sub-pixels in the region to obtain the drive signals for the sub-pixels.

6. A method as claimed in claim 5, wherein the sub-pixel region is a display area comprising a first sub-pixel group and a second sub-pixel group of the at least two sub-pixel groups.

7. A computer program product comprising code stored in a non-transitory computer readable medium, said code enabling a processor to execute the steps of the method as claimed in claim 1, the steps being:

a multiple-primary conversion for receiving the input image signal and being performed under a constraint, and

first determining the constraint by substantially matching local display luminances associated with the at least two sub-pixel groups with corresponding local input luminances of input pixels of the input image signal, thereby obtaining a display luminance pattern defined by the display pixels corresponding to an input luminance pattern defined by the input pixels associated with the display pixels; and

,

wherein the first determining the constraint comprises;

selecting a first display area comprising a first sub-pixel group and a second sub-pixel group of the at least two sub-pixel groups, and a second display area comprising the first sub-pixel group and being a sub-area of the first display area,

computing a first input luminance for input pixels associated with the first display area,

computing a second input luminance for input pixels associated with the second display area, and

second determining the constraint to obtain a substantially matching ratio or difference between on the one hand the first input luminance and the second input luminance and on the other hand a first display luminance being the luminance of the sub-pixels covered by the first display area and a second display luminance being the luminance of the sub-pixels covered by the second display area.

8. A method of converting an input image signal into a drive signal for driving sub-pixels of a display device comprising display pixels having at least two sub-pixel groups being able to contribute to luminance information displayed, the conversion comprising:

a multi-primary conversion for receiving the input image signal and being performed under a constraint, and

first determining the constraint by substantially matching local. display luminances associated with the at least two sub-pixel groups with corresponding local input luminances of input pixels of the input image signal, thereby obtaining a display luminance pattern defined by the display pixels corresponding to an input luminance pattern defined by the input pixels associated with the display pixels;

wherein the first determining the constraint comprises;

selecting a first display area comprising a first sub-pixel group and a second sub-pixel group of the at least two sub-pixel groups, and a second display area comprising the first sub-pixel group and being a sub-area of the first display area,

computing a first input luminance for input pixels associated with the first display area,

computing a second input luminance for input pixels associated with the second display area, and

second determining the constraint to obtain a substantially matching ratio or difference between on the one hand the first input luminance and the second input luminance and on the other hand a first display luminance being the luminance of the sub-pixels covered by the first display area and a second display luminance being the luminance of the sub-pixels covered by the second display area; and

,

the computing the first input luminance uses a first filtering operation with a first filter kernel at least covering the first display area, first filter coefficients of the first filtering are proportional to areas of the sub-pixels being covered by the first filter kernel,

the computing the second input luminance comprises a second filtering operation with a second filter kernel covering the second display area, second filter coefficients of the second filtering are proportional to areas of the sub-pixels being covered by the second filter kernel.

9. A method of converting an input image signal into a drive signal for driving sub-pixels of a display device comprising display pixels having at least two sub-pixel groups being able to contribute to luminance information displayed, the conversion comprising:

a multi-primary conversion for receiving the input image signal and being performed under a constraint, and

first determining the constraint by substantially matching local display luminances associated with the at least two sub-pixel groups with corresponding local input luminances of input pixels of the input image signal, thereby obtaining a display luminance pattern defined by the display pixels corresponding to an input luminance pattern defined by the input pixels associated with the display pixels;

wherein the first determining the constraint comprises;

selecting a first display area comprising a first sub-pixel group and a second sub-pixel group of the at least two sub-pixel groups, and a second display area comprising the first sub-pixel group and being a sub-area of the first display area,

computing a first input luminance for input pixels associated with the first display area,

computing a second input luminance for input pixels associated with the second display area, and

second determining the constraint to obtain a substantially matching ratio or difference between on the one hand the first input luminance and the second input luminance and on the other hand a first display luminance being the luminance of the sub-pixels covered by the first display area and a second display luminance being the luminance of the sub-pixels covered by the second display area; and

,

the computing the first input luminance and the second input luminance uses a filtering operation with a filter kernel covering a delta area of the first display area and the second display area, filter coefficients of the filtering are proportional to areas of the sub-pixels being covered by the delta area.

10. A method of converting an input image signal into a drive signal for driving sub-pixels of a display device comprising display pixels having at least two sub-pixel groups being able to contribute to luminance information displayed, the conversion comprising:

a multi-primary conversion for receiving the input image signal and being performed under a constraint,

first determining the constraint by substantially matching local display luminances associated with the at least two sub-pixel groups with corresponding local input luminances of input pixels of the input image signal, thereby obtaining a display luminance pattern defined by the display pixels corresponding to an input luminance pattern defined by the input pixels associated with the display pixels;

second determining local input luminances associated with sub-pixels covered by a sub-pixel region including and surrounding a particular one of the sub-pixels having a particular color to obtain an output signal of the multi-primary conversion,

distributing the output image signal of the multi-primary conversion of the sub-pixel over the sub-pixels of the sub-pixel region to obtain a distributed image signal, the distributing being performed in accordance with the local input luminances associated with the sub-pixels covered by the sub-pixel region, to obtain a luminance distribution across the sub-pixels corresponding to the luminance distribution of the local input luminances,

accumulating the distributed image signal per sub-pixels for all sub-pixels in the region to obtain the drive signals DS for the sub-pixels;

wherein the second determining local input luminances comprises

computing a total luminance per particular display primary associated with a particular one of the sub-pixels by using a filtering operation with a filter kernel covering an input pixel region corresponding to the sub-pixel region, wherein filter coefficients of the filtering are proportional to areas of the sub-pixels being covered by the filter kernel and being associated with a particular color of the particular one of the sub-pixels, and

third determining luminance contributions for each one of the sub-pixels covered by the sub-pixel region and having the particular color by multiplying the total luminance with the relative area of a particular one of these sub-pixels in the sub-pixel region and with the local input luminance of this particular one of the sub-pixels in the input image.

11. A conversion unit for converting an input image signal into a drive signal for driving sub-pixels of a display device comprising display pixels having at least two sub-pixel groups being able to contribute to luminance information displayed, the conversion unit comprises:

a multi-primary converter for receiving the input image signal and being performed under a constraint, and

a constraint determining unit for determining the constraint by substantially matching local display luminances associated with the at least two sub-pixel groups with corresponding local input luminances of input pixels of the input image signal, thereby obtaining a display luminance pattern defined by the display pixels corresponding to an input luminance pattern defined by the input pixels associated with the display pixels; and

,

wherein the determining the constraint comprises;

selecting a first display area comprising a first sub-pixel group and a second sub-pixel group of the at least two sub-pixel groups, and a second display area comprising the first sub-pixel group and being a sub-area of the first display area,

computing a first input luminance for input pixels associated with the first display area,

computing a second input luminance for input pixels associated with the second display area, and

determining the constraint to obtain a substantially matching ratio or difference between on the one hand the first input luminance and the second input luminance and on the other hand a first display luminance being the luminance of the sub-pixels covered by the first display area and a second display luminance being the luminance of the sub-pixels covered by the second display area.