Editing of digital images, including (but not limited to) highlighting and shadowing of image areas

• US 7,639,396 B2
• Filed: 07/26/2006
• Issued: 12/29/2009
• Est. Priority Date: 12/28/2005
• Status: Expired due to Fees

• Current Assignee: KWE International, Inc.
• Original Assignee: KWE International, Inc.
• Inventors: Bezryadin, Sergey N.
• Primary Examiner(s): Hasksins; Twyler L
• Assistant Examiner(s): Beckley; Jonathan R
• Application Number:
  US11/494,393
• Publication Number:
  US 20070154083A1
• Time in Patent Office: 1,252 Days
• Field of Search: 358/1.9, 358/518, 358/504, 358/520, 358/530, 358/515, 358/443, 348/419, 348/428, 348/581, 345/428, 345/581
• US Class Current: 358/1.9
• CPC Class Codes: G06T 2207/10024 Color image
• CPC Class Codes: G06T 5/90 Dynamic range modification of images or parts thereof
• CPC Class Codes: H04N 1/4072 dependent on the contents of the original
• CPC Class Codes: H04N 1/4092 Edge or detail enhancement

Abstract

In a digital image having pixels p_i (i=1, 2, . . . ) and a brightness B(p_i) at each pixel p_i, the global dynamic range of an image is changed by replacing the brightness B(p_i) with the brightness B*(p_i)=B(p_i)×(B₀/B_avg(p_i))^ε, where B₀ and ε are predefined constants, and B_avg(p_i) is some average brightness value, e.g. the mean brightness over a region R(p_i) containing the pixel p_i. The local dynamic range is not changed significantly in some embodiments. The brightness of an image at a pixel can be defined so that multiplication of the brightness by a positive value k corresponds to multiplication of tristimulus values by k. In some embodiments, a color coordinate system is used with the brightness being one of the coordinates.

Claims

1. A circuitry-implemented method comprising image editing, the method comprising:

(1) obtaining digital data representing image portions p₁, p₂, . . . , wherein for each image portion p (p=p₁, p₂, . . . ), the digital data define a brightness B(p) of the portion p;

(2) for each image portion p_i of a plurality of the image portions p₁, p₂, . . . , obtaining a brightness B*(p_i) of a modified image, such that;

B*(p_i)=ƒ

(B(p_i),B_avg(p_i))

wherein;

B_avg(p_i) is a function of the brightness values B(v) of image portions p in an image region R(p_i) containing a plurality of image portions including the portion p_i; and

ƒ

is a predefined non-identity function such that for all i, the function ƒ

(B(p_i),y) is strictly monotonic my for each B(p_i), and for each B_avg(p_i), the function ƒ

(x,B_avg(p_i) is strictly increasing in x.

2. The method of claim 1 wherein for all i, the function ƒ

(B(p_i),y) is strictly decreasing in y for each B(p_i).

3. The method of claim 1 wherein for all i, the function ƒ

(B(p_i),y) is strictly increasing in y for each B(p_i).

4. The method of claim 1 wherein for all i,

ƒ

(x,B_avg(p_i)=x·

F(B_avg)

for some function F.

5. The method of claim 4 wherein there exists a positive value B₀ such that F(B₀)=1.

6. The method of claim 5 wherein B_min≦

B₀≦

B_max, wherein B_min is the minimum of the brightness values B(p_i) and B_max is the maximum of the brightness values B(p_i).

7. The method of claim 5 wherein:

B*(p_i)=B(p_i)×

(B₀/B_avg(p_i))^ε

where ε

is a non-zero constant.

8. The method of claim 7 wherein c is greater than −

1 and less than 1.

9. Circuitry for performing the method of claim 7.

10. One or more computer-readable mediums comprising one or more computer instructions to cause a computer system to perform the method of claim 7.

11. The method of claim 1 wherein the operation (2) is performed for a plurality of portions pt with each image region R(p_i) having a predefined geometry with respect to the respective portion p_i.

12. The method of claim 1 wherein B_avg(p_i) is a weighted average of the brightness values of the image region R(p_i), and the sum of the weights is equal to 1.

13. The method of claim 1 wherein B_avg is the mean of the brightness values in the image region R(p_i).

14. The method of claim 1 wherein for each image portion p (p=p₁, p₂, . . . ), the digital data represent a color S(p) of the portion p, the color S(p) having tristimulus values T₁(p), T₂(p), T₃(p) in a predefined color coordinate system, wherein for any color S having tristimulus values T₁, T₂, T₃ in said predefined color coordinate system and having a brightness B, for any positive value k in a range of positive values, a color with tristimulus values kT₁, kT₂, kT₃ has a brightness kB.

15. The method of claim 14 wherein

$B=\sqrt{g_{11}}$

T 1 2 + g 22 ⁢

T 2 2 + g 33 ⁢

T 3 2 + g 12 ⁢

T 1 ⁢

T 2 + g 13 ⁢

T 1 ⁢

T 3 + g 23 ⁢

T 2 ⁢

T 3

wherein g₁₁, g₂₂, g₃₃, g₁₂, g₁₃, g₂₃ are predefined constants, and g₁₁, g₂₂, g₃₃ are not equal to zero.

16. The method of claim 14 wherein:

for each image portion p (p=p₁, p₂, . . . ), the digital data represent coordinates of the color S(p) of the portion p in a first coordinate system, wherein for a color S having tristimulus values T₁, T₂, T₃ in a second coordinate system which is said predefined coordinate system, the coordinates of the color S in the first coordinate system are coordinates S₁, S₂, S₃, or a linear transformation of the coordinates S₁, S₂, S₃, wherein;

(A) the coordinate S₁ is defined by B or

(B) the coordinate S₁ is defined by B and by a sign of a predefined function of one or more of T₁, T₂, T₃.

17. The method of claim 16 wherein:

B=√

{square root over (α

₁²(T₁,T₂,T₃)+α

₂²(T₁,T₂,T₃)+α

₃²(T₁,T₂,T₃))}{square root over (α

₁²(T₁,T₂,T₃)+α

₂²(T₁,T₂,T₃)+α

₃²(T₁,T₂,T₃))}{square root over (α

₁²(T₁,T₂,T₃)+α

₂²(T₁,T₂,T₃)+α

₃²(T₁,T₂,T₃))}

wherein

α

₁(T₁,T₂,T₃)=α

₁₁×

T₁+α

₁₂×

T₂+α

₁₃×

T₃

α

₂(T₁,T₂,T₃)=α

₂₁×

T₁+α

₂₂×

T₂+α

₂₃×

T₃

α

₃(T₁,T₂,T₃)=α

₃₁×

T₁+α

₃₂×

T₂+α

₃₃×

T₃

wherein α

₁₁, α

₁₂, α

₃, α

₂₁, α

₂₂, α

₂₃, α

₃₁, α

₃₂, α

₃₃ are predefined numbers such that the following matrix Λ

is non-degenerate;

$\mathrm{\Lambda <br><br>}=\left[\begin{array}{ccc}{\mathrm{\alpha <br><br>}}_{11}& {\mathrm{\alpha <br><br>}}_{12}& {\mathrm{\alpha <br><br>}}_{13}\\ {\mathrm{\alpha <br><br>}}_{21}& {\mathrm{\alpha <br><br>}}_{22}& {\mathrm{\alpha <br><br>}}_{23}\\ {\mathrm{\alpha <br><br>}}_{31}& {\mathrm{\alpha <br><br>}}_{32}& {\mathrm{\alpha <br><br>}}_{33}\end{array}\right]$

18. The method of claim 17 wherein α

₁(T₁,T₂,T₃), α

₂(T₁,T₂,T₃), α

₃(T₁,T₂,T₃) are tristimulus values corresponding to 70%-orthonormal color matching functions.

19. The method of claim 17 wherein:

the value T₁ is one of values D, F, F, the value T₂ is another one of D, F, F, and the value T₃ is the third one of D, E, F, where

$\left[\begin{array}{c}D\\ E\\ F\end{array}\right]=A<br><br>\left[\begin{array}{c}X\\ Y\\ Z\end{array}\right]$

where the matrix A has elements which, up to rounding, are as follows;

$A=\left[\begin{array}{ccc}0.205306& 0.712507& 0.467031\\ -0.365451& 1.011998& -0.610425\\ 1.853667& -1.279659& -0.442859\end{array}\right]$

where X Y, Z are the coordinates of the color S in the CIE 1931 XYZ color coordinate system for a 2°

field;

wherein up to a constant multiple, Λ

is a 70%-orthonormal matrix.

20. Circuitry for performing the method of claim 1.

21. One or more computer-readable mediums comprising one or more computer instructions to cause a computer system to perform the method of claim 1.

22. A data transmission method comprising transmitting a computer program over a network link, wherein the computer program is operable to cause a computer system to perform the method of claim 1.

23. A data transmission method comprising transmitting a computer program over a network link, wherein the computer program is operable to cause a computer system to perform the method of claim 7.