Image pixel transformation

• US 20070091435A1
• Filed: 10/21/2005
• Published: 04/26/2007
• Est. Priority Date: 10/21/2005
• Status: Abandoned Application

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: McClelland, Paul, Juenger, Andrew, Garner, Grant, Zavarehi, Masoud
• Application Number:
  US11/256,011
• Publication Number:
  US 20070091435A1
• Time in Patent Office: Days
• US Class Current: 359/459
• CPC Class Codes: G03B 21/2053 Intensity control of illuminating light controlled by video signal processing H04N5/74 or H04N9/31
• CPC Class Codes: H04N 21/42202 environmental sensors, e.g. for detecting temperature, luminosity, pressure, earthquakes
• CPC Class Codes: H04N 21/4318 by altering the content in the rendering process, e.g. blanking, blurring or masking an image region image enhancement or restoration in general G06T5/00
• CPC Class Codes: H04N 5/58 in dependence upon ambient light
• CPC Class Codes: H04N 9/3182 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 Class Codes: H04N 9/3194 including sensor feedback

Abstract

Various embodiments for image pixel transformation are disclosed.

Claims

1. An method comprising:

transforming target luminances of image pixels to projection luminances using a light value and a reflectivity of a projection screen.

2. The method of claim 1, wherein the transforming of the target luminances of each of the image pixels uses target luminances of other of the image pixels.

3. The method of claim 2, wherein the transforming of the target luminances uses a distribution of the target luminances of the image pixels.

4. The method of claim 1, wherein the transforming is based on available luminance levels of a projector.

5. The method of claim 4, wherein the available luminance levels of the projector are apportioned amongst the target luminances of the image pixels.

6. The method of claim 1, further comprising sensing an ambient light value, wherein the light value includes the ambient light value.

7. The method of claim 1, further comprising inputting an ambient light value, wherein the light value includes the ambient light value.

8. The method of claim 1, further comprising selecting an ambient light value, wherein the light value includes the ambient light value.

9. The method of claim 1, wherein the image pixels are assigned into regimes using target luminances of the image pixels, the light value and the reflectivity of the screen.

10. The method of claim 9, wherein a first one of the regimes has an upper boundary equal to the reflectivity of the screen.

11. The method of claim 10, wherein the target luminances of pixels in the first one of the regimes are transformed according to the following:

P_ij=1−

1/R+T_ij/R, where;

P_ij=a projection luminance for an image pixel have coordinates i, j,

R=reflectivity of the screen; and

T_ij=target luminance of image pixel having coordinates i, j.

12. The method of claim 9, wherein a first one of the regimes has a lower bound equal to the reflectivity of the screen multiplied by the light value and an upper bound equal to the reflectivity of the screen plus the reflectivity of the screen multiplied by the light value.

13. The method of claim 12, wherein the target luminance of pixels in the first one of the regions are transformed according the following:

P_ij=T_ij/R, where;

P_ij=a projection luminance for an image pixel have coordinates i, j,

T_ij=target luminance of image pixel having coordinates i, j; and

R=reflectivity of the screen.

14. The method of claim 9, wherein a first one of the region has an upper bound equal to one white Lambertian and a lower bound equal to one white Lambertian less the reflectance of the screen.

15. The method or claim 14, wherein the target luminance of the pixels in the first one of the regimes is transformed according to the following:

P_ij=T_ij/R−

A, where;

P_ij=a projection luminance for an image pixel have coordinates i, j,

T_ij=target luminance of an image pixel having coordinates i, j;

R=reflectivity of the screen; and

A=a light value.

16. The method of claim 9, further comprising applying different transforms to the target luminances of image pixels in different regimes to transform the target luminances to projection luminances.

17. The method of claim 16, wherein the different transforms are scaled using a relative distribution of the target luminances of the image pixels among the regimes.

18. The method of claim 17, wherein the transforms are scaled using a percentage of total target luminances in each regime.

19. The method of claim 18 wherein the transforms are scaled using a different power of the percentage of the total target luminances in each regime.

20. The method of claim 1, wherein target luminances of image pixels are transformed to projection luminances according to the following:

P_ij=N_LT_ij/R for 0≦

T_ij<

RA, where;

N_L=F(n_L/n_TOT),

n_L=number of pixels whose target luminances T_ij are less than the reflectivity of the screen,

N_TOT=total number of image pixels,

R=reflectivity of the screen; and

T_ij=target luminance of a pixel having coordinates i, j.

21. The method of claim 1, wherein target luminances of image pixels are transformed to projection luminances according to the following:

P_ij(Tij)=aT_ij³+bT_ij²+cT_ij+d for RA≦

T_ij≦

1, where

P(RA)=N_LA

P′

(RA)=N_M/R,

P(1)=1,

P′

(1)=N_H/R,

N_L=F(n_L/n_TOT),

n_L=number of pixels whose target luminances T_ij are less than the reflectivity of the screen,

N_M=F(n_M/n_TOT),

n_M=number of pixels whose target luminances T_ij are greater than R×

A and less than R(1+A),

N_H=F(n_H/n_TOT),

n_H=number of pixels whose target luminances T_ij are greater than 1−

R,

n_TOT=total number of pixels,

R=reflectivity of the screen,

T_ij=target luminance of a pixel having coordinates ij, and

A=a light value.

22. The method of claim 1, further comprising adjusting color components of the image pixels using transformation of the target luminances to projection luminances of the image pixels.

23. The method of claim 1, wherein transforming further comprises transforming target luminances of image pixels to target brightnesses of image pixels, transforming the target brightnesses to projection brightnesses and transforming projection brightnesses to the projection luminances.

24. The method of claim 1, wherein the target luminances of image pixels are transformed to projection luminances according to the following:

P_ij=N_LA+((N_H/R)(T_x−

1)+1−

N_LA) (T_ij−

AR)/(T_x−

AR) for RA≦

T_ij≦

T_x, where;

N_L=F(n_L/n_TOT);

n_L=number of pixels whose target luminances T_ij are less than the reflectivity of the screen,

N_M=F(n_M/n_TOT),

n_M=number of pixels whose target luminances T_ij are greater than RA and less than R(1+A),

N_H=F(n_H/n_TOT),

n_H=number of pixels whose target luminances T_ij are greater than 1−

R,

n_TOT=total number of pixels,

R reflectivity of the screen,

T_ij=target luminance of a pixel having coordinates ij,

A=a light value, and

T_x=R(1+(N_M−

N_L)A−

N_H)/(N_M−

N_H).

25. The method of claim 1, wherein target luminance of pixels are transformed to projection luminances according to the following:

P_ij=1−

N_H/R+N_HT_ij/R for T_x≦

T_ij≦

1, where;

N_L=F(n_L/n_TOT),

n_L=number of pixels whose target luminances T_ij are less than the reflectivity of the screen,

N_M=F(n_M/n_TOT),

n_M=number of pixels whose target luminances T_ij are greater than RA and less than R(1+A),

N_H=F(n_H/n_TOT),

n_Hnumber of pixels whose target luminances T_ij are greater than 1−

R.

n_TOT=total number of pixels,

R=reflectivity of the screen,

T_ij=target luminance of a pixel having coordinates ij,

A=a light value, and

Tx=R(1+(N_M−

N_L)A−

N_H)/(N_M−

N_H).

26. A computer readable medium comprising:

instructions to transform target luminances of image-pixels to projection luminances using a light value and a reflectivity of a screen.

27. An apparatus comprising:

a controller configured to transform target luminances of image pixels to projection luminances using a light value and a reflectivity of a screen.

28. The apparatus of claim 27, further comprising a projector.

29. A method comprising:

obtaining a reflectivity of a surface upon which an image is to be projected;

obtaining a light value; and

a step for closely matching perceived brightness of pixels in a projection with ambient light to viewed perceived brightness of pixels when viewed with a white Lambertian screen without ambient light.

30. A method comprising:

obtaining a reflectivity of a surface upon which an image is to be projected;

obtaining a light value; and

a step for closely matching viewed luminances of pixels in a projection with ambient light to viewed luminances of pixels when viewed with a white Lambertian screen without ambient light.