Re-coloring a color image
View Patent ↗Technology for re-coloring a region of a color image including determining an original base color in a region of a color image; establishing at least one shading parameter in the region of the color image; and combining a new base color with the at least one shading parameter in the region of the color image thereby producing a re-colored region of the color image.
1. A method for re-coloring a color image comprising:
determining an original base color in a predetermined region of the color image by implementing an ambient/diffuse shading model using a processing unit, wherein, the ambient/diffuse shading model is implemented according to:
E total E base (1 +k diffuse (cos Θ+1))
where E is the energy relationship of light and color in the energy domain, E total is the total color, E base represents the original base color, the term k diffuse (cos Θ−1) represents the at least one shading parameter and Θ is the angle formed between a surface normal in the region and a corresponding vector pointing toward a light source in the image or wherein the ambient/diffuse shading model is implemented according to E total =E light E base (k ambient +k diffuse cos Θ);
establishing at least one shading parameter in the predetermined region of the color image by implementing the ambient/diffuse shading model using the processing unit;
retrieving a texture map comprising a plurality of base colors and a pattern defining a spatial distribution of the plurality of base colors; and
combining the texture map with the at least one shading parameter for the predetermined region of the color image thereby producing a re-colored predetermined region of the color image using the processing unit having the pattern applied across the region of the color image.
2. The method according to claim 1 wherein,
the ambient/diffuse shading model is implemented according to:
E total =E light E base ( k ambient +k diffuse cos Θ)
which under the assumptions
E light =1
k ambient +k diffuse =1
simplifies to
E total =E base (1 +k diffuse (cos Θ−1))
where E is the energy relationship of light and color in the energy domain, E total is the total color, E base represents the base color, the term 1+k diffuse (cos Θ−1) represents the at least one shading parameter and Θ is the angle formed between a surface normal in the region and a corresponding vector pointing toward a light source in the image, or E i =E base (1+k diffuse (cos Θ i −1))
where E is the energy relationship of light and color in the energy domain, E i is the total color, E base represents the base color, the term k diffuse (cos Θ−1) represents the at least one shading parameter and Θ is the angle formed between a surface normal in the region and a corresponding vector pointing toward a light source in the image, and where i represents a pixel within the region, Θ i being the angle formed at pixel i, or
E c,i =E c,base (1 +k diffuse (cos Θ−1))
where E is the energy relationship of light and color in the energy domain, E i is the total color, E base represents the base color, the term k diffuse (cos Θ−1) represents the at least one shading parameter and Θ is the angle formed between a surface normal in the region and a corresponding vector pointing toward a light source in the image, where i represents a pixel within the region, Θ i being the angle formed at pixel i, and where the subscript c indicates a color channel, or
E total =E base (1 +k diffuse (cos Θ−1))
where E is the energy relationship of light and color in the energy domain, E total is the total color, E base represents the base color, the term k diffuse (cos Θ−1) represents the at least one shading parameter and Θ is the angle formed between a surface normal in the region and a corresponding vector pointing toward a light source in the image; and,
wherein the base color E base is the original base color and is determined by identifying the maximum color of the region, where the surface normal is pointing directly toward the light source so that Θ=0 and cos Θ=1, and:
E
base
=
E
maximum
1
+
k
diffuse
(
cos
(
0
)
-
1
)
where E is the energy relationship of light and color in the energy domain, E total is the total color, E base represents the base color, the term k diffuse (cos Θ−1) represents the at least one shading parameter and Θ is the angle formed between a surface normal in the region and a corresponding vector pointing toward a light source in the image; and,
wherein the diffuse coefficient k diffuse is determined by identifying the minimum color of the region, where the surface normal is pointing away from the light source so that Θ=π/2 and cos Θ=0, and:
E minimum =E base (1 +k diffuse (cos(π/2)−1))
from which k diffuse is solved:
k diffuse =( E base −E minimum )/ E base , or
E i E base (1 +k diffuse (cos Θ i −1))
where E is the energy relationship of light and color in the energy domain, E i is the total color, E base represents the base color, the term k diffuse (cos Θ i −1) represents the at least one shading parameter and Θ is the angle formed between a surface normal in the region and a corresponding vector pointing toward a light source in the image, and where i represents a pixel within the region, Θ i being the angle formed at pixel i; and,
wherein for each pixel i in the region, the value for cos Θ i is computed from the shading model:
E i E base (1 +k diffuse (cos Θ i −1))
which may be solved for cos Θ i and simplified to:
cos Θ i =( E i −E minimum )/( E base −E minimum ), or
E total =E base (1 +k diffuse (cos Θ−1))
where E is the energy relationship of light and color in the energy domain, E total is the
total color, E base represents the base color, the term k diffuse (cos Θ−1) represents the at least one shading parameter and Θ is the angle formed between a surface normal in the region and a corresponding vector pointing toward a light source in the image; and,
wherein a new base color, E base ′ is substituted into the shading equation for each pixel in the region, producing a re-colored second region:
E total ′=E base ′(1 +k diffuse (cos Θ−1))
where the prime, ′, refers to the new base color, as opposed to the original base color.
3. The method according to claim 1 wherein;
determining the original base color is performed by converting the predetermined region of the color image to a predetermined color space comprising a plurality of color channels; and
the establishing and combining steps are performed upon the predetermined region for each color channel of the plurality of color channels.
4. The method according to claim 1 wherein, the texture map is obtained using a synthesis procedure executed by the processing unit.
5. The method according to claim 1 wherein, the original base color is colorless.
6. The method according to claim 1 wherein, each color in the plurality of colors within the texture map are defined in a predetermined color space by a set of neutral values.
7. The method according to claim 1 wherein, establishing at least one shading parameter comprises establishing the at least one shading parameter for a color component of a predetermined color space representation of the colors in the predetermined region showing the largest variation within the predetermined region.
8. A method for re-coloring a color image comprising:
determining a base color in a first predetermined region of the color image by implementing an ambient/diffuse shading model using a processing unit, wherein, the ambient/diffuse shading model is implemented according to:
E total =E base (1 +k diffuse (cos Θ−1))
where E is the energy relationship of light and color in the energy domain, E total is the total color, E. base represents the original base color the term k diffuse (cos Θ−1) represents the at least one shading parameter and Θ is the angle formed between a surface normal in the region and a corresponding vector pointing toward a light source in the image or wherein the ambient/diffuse shading model is implemented according to E total =E light E base (k ambient +k diffuse cos Θ);
establishing at least one shading parameter in a second predetermined region of the color image by implementing the ambient/diffuse shading model using the processing unit; and
generating a new second predetermined region of the color image by combining the at least one shading parameter for the second predetermined region of the color image with the base color.
9. The method according to claim 8 wherein,
the ambient/diffuse shading model is implemented according to:
E total =E light E base ( k ambient +k diffuse cos Θ)
which under the assumptions
E light =1
k ambient +k diffuse =1
simplifies to
E total =E base (1 +k diffuse (cos Θ−1))
where E is the energy relationship of light and color in the energy domain, E total is the total color, E base represents the base color, the term k diffuse (cos Θ−1) represents the at least one shading parameter and Θ is the angle formed between a surface normal in the region and a corresponding vector pointing toward a light source in the image, or
E i E base (1 +k diffuse (cos Θ i −1))
where E is the energy relationship of light and color in the energy domain, E i is the total color, E base represents the base color, the term k diffuse (cos Θ−1) represents the at least one shading parameter and Θ is the angle formed between a surface normal in the region and a corresponding vector pointing toward a light source in the image, and where i represents a pixel within the region, Θ i being the angle formed at pixel i, or
E c,i =E c,base (1 +k diffuse (cos Θ i −1))
where E is the energy relationship of light and color in the energy domain, E c,i is the total color, E base represents the base color, the term k diffuse (cos Θ−1) represents the at least one shading parameter and Θ is the angle formed between a surface normal in the region and a corresponding vector pointing toward a light source in the image, where i represents a pixel within the region, Θ i being the angle formed at pixel i, and where the subscript c indicates a color channel, or
E total I=E base (1 +k diffuse (cos Θ−1))
where E is the energy relationship of light and color in the energy domain, E total is the total color, E base represents the base color, the term k diffuse (cos Θ−1) represents the at least one shading parameter and Θ is the angle formed between a surface normal in the region and a corresponding vector pointing toward a light source in the image; and, wherein the base color E base is the original base color and is determined by identifying the maximum color of the region, where the surface normal is pointing directly toward the light source so that Θ=0 and cos Θ=1, and:
E
base
=
E
maximum
1
+
k
diffuse
(
cos
(
0
)
-
1
)
=
E
maximum
,
or
E
total
=
E
base
(
1
+
k
diffuse
(
cos
θ
-
1
)
)
where E is the energy relationship of light and color in the energy domain, E total is the total color, E base represents the base color, the term k diffuse (cos Θ−1) represents the at least one shading parameter and Θ is the angle formed between a surface normal in the region and a corresponding vector pointing toward a light source in the image; and,
wherein the diffuse coefficient k diffuse is determined by identifying the minimum color of the region, where the surface normal is pointing away from the light source so that Θ=π/2 and cos Θ=0, and:
E minimum =E base (1 +k diffuse (cos(π/2)−1))
from which k diffuse is solved:
k diffuse =( E base −E minimum )/ E base , or E ·sub· i=E base (1 +k diffuse (cos Θ i −1))
where E is the energy relationship of light and color in the energy domain, E i is the total color, E base represents the base color, the term k diffuse (cos Θ i −1) represents the at least one shading parameter and Θ is the angle formed between a surface normal in the region and a corresponding vector pointing toward a light source in the image, and where i represents a pixel within the region, Θ i being the angle formed at pixel i; and,
wherein for each pixel i in the region, the value for cos Θ i is computed from the shading model:
E i =E base (1 +k diffuse (cos Θ i −1))
which may be solved for cos Θ i and simplified to:
cos Θ i =( E i −E minimum )/( E base −E minimum ), or
E total =E base (1 +k diffuse (cos Θ−1))
where E is the energy relationship of light and color in the energy domain, E total is the total color, E base represents the base color, the term k diffuse (cos Θ−1) represents the at least one shading parameter and Θ is the angle formed between a surface normal in the region and a corresponding vector pointing toward a light source in the image; and,
wherein a new base color, E base ′ is substituted into the shading equation for each pixel in the region, producing a re-colored second region:
E total ′=E base (1 +k diffuse (cos Θ−1))
where the prime, ′, refers to the new base color, as opposed to the original base color.
10. The method according to claim 8 wherein,
determining the base color is performed by converting the first predetermined region of the color image to a predetermined color space comprising a plurality of color channels; and
the establishing and combining steps are performed upon the second predetermined region for each color channel of the plurality of color channels.
11. The method according to claim 8 wherein, the first and second predetermined regions of the image are the same region.
12. The method according to claim 8 wherein, the base color is colorless.
13. The method according to claim 8 wherein, establishing at least one shading parameter comprises establishing the at least one shading parameter for a color component of a predetermined color space representation of the colors in the second predetermined region showing the largest variation within the second predetermined region.
14. The method according to claim 8 further comprising:
determining an original base color for the second predetermined region of the color image by implementing the ambient/diffuse shading model using the processing unit;
identifying a third predetermined regions of the color image having the same original base color as the first predetermined region using the ambient/diffuse shading model and the processing unit;
establishing at least one shading parameter in the third predetermined region of the color image by implementing the ambient/diffuse shading model using the processing unit; and
generating a new third predetermined region of the color image by combining the at least one shading parameter for the third predetermined region of the color image with a new base color.
15. A method for re-coloring a color image comprising:
determining a base color in a predetermined region of the color image by implementing an ambient/diffuse shading model using a processing unit, wherein the ambient/diffuse shading model is implemented according to:
E total =E base (1 +k diffuse (cos Θ−1))
where E is the energy relationship of light and color in the energy domain, E total is the total color, E base re resents the original base color, the term k diffuse (cos Θ−1) represents the at least one shading parameter and Θ is the angle formed between a surface normal in the region and a corresponding vector pointing toward a light source in the image or wherein the ambient/diffuse shading model is implemented according to E total =E liqht E base (k aambient +k diffuse cos Θ);
establishing at least one shading parameter in the predetermined region of the color image by implementing the ambient/diffuse shading model using the processing unit;
generating a new predetermined region of the color image by either combining the at least one shading parameter for the predetermined region of the color image with a new base color defined in a predetermined color space by a set of neutral values or not adding a new base color into an energy equation associated with the ambient/diffuse shading model when combining the new base color with the at least one shading parameter for the predetermined region of the color image.
16. The method according to claim 15 wherein, the
ambient/diffuse shading model is implemented according to:
E total =E light E base ( k ambient +k diffuse cos Θ)
which under the assumptions
E light =1
k ambient +k diffuse =1
simplifies to
E total =E base (1 +k diffuse (cos Θ−1))
where E is the energy relationship of light and color in the energy domain, E total is the total color, E base represents the base color, the term k diffuse (cos Θ−1) represents the at least one shading parameter and Θ is the angle formed between a surface normal in the region and a corresponding vector pointing toward a light source in the image, or
E c,i =E c,base (1 +k diffuse (cos Θ i −1))
where E is the energy relationship of light and color in the energy domain, E c,i is the total color, E base represents the base color, the term k diffuse (cos Θ−1) represents the at least one shading parameter and Θ is the angle formed between a surface normal in the region and a corresponding vector pointing toward a light source in the image, and where i represents a pixel within the region, Θ i being the angle formed at pixel i, or
E c,i E c,base (1 +k diffuse (cos Θ i −1))
where E is the energy relationship of light and color in the energy domain, E c,i is the total color, E base represents the base color, the term k diffuse (cos Θ−1) represents the at least one shading parameter and Θ is the angle formed between a surface normal in the region and a corresponding vector pointing toward a light source in the image, where i represents a pixel within the region, Θ i being the angle formed at pixel i, and where the subscript c indicates a color channel, or
E total =E base (1 +k diffuse (cos Θ−1))
where E is the energy relationship of light and color in the energy domain, E total is the total color, E base represents the base color, the term k diffuse (cos Θ−1) represents the at least one shading parameter and Θ is the angle formed between a surface normal in the region and a corresponding vector pointing toward a light source in the image; and,
wherein the base color E base is the original base color and is determined by identifying the maximum color of the region, where the surface normal is pointing directly toward the light source so that Θ=0 and cos Θ=1, and:
E
base
=
E
maximum
1
+
k
diffuse
(
cos
(
0
)
-
1
)
=
E
maximum
,
or
E
total
=
E
base
(
1
+
k
diffuse
(
cos
θ
-
1
)
)
where E is the energy relationship of light and color in the energy domain, E total is the total color, E base represents the base color, the term k diffuse (cos Θ−1) represents the at least one shading parameter and Θ is the angle formed between a surface normal in the region and a corresponding vector pointing toward a light source in the image; and,
wherein the diffuse coefficient k diffuse is determined by identifying the minimum color of the region, where the surface normal is pointing away from the light source so that Θ=π/2 and cos Θ=0, and:
E minimum =E base (1 +k diffuse (cos(π/2)−1))
from which k diffuse is solved:
k diffuse =( E base −E minimum )/ E base , or
E i =E base (1 +k diffuse (cos Θ i −1))
where E is the energy relationship of light and color in the energy domain, E total is the total color, E base represents the base color, the term k diffuse (cos Θ i −1) represents the at least one shading parameter and Θ is the angle formed between a surface normal in the region and a corresponding vector pointing toward a light source in the image, and
where i represents a pixel within the region, Θ i being the angle formed at pixel i; and, wherein for each pixel i in the region, the value for cos Θ i is computed from the shading model:
E i =E base (1 +k diffuse (cos Θ i −1))
which may be solved for cos Θ i and simplified to:
cos Θ i =( E 1 −E minimum )/( E base −E minimum ), or
E total =E base (1 +k diffuse (cos Θ−1))
where E is the energy relationship of light and color in the energy domain, E total is the total color, E base represents the base color, the term k diffuse (cos Θ−1) represents the at least one shading parameter and Θ is the angle formed between a surface normal in the region and a corresponding vector pointing toward a light source in the image; and,
wherein a new base color, E base ′ is substituted into the shading equation for each pixel in the region, producing a re-colored second region:
E total ′=E base ′(1 +k diffuse (cos Θ−1))
where the prime, ′, refers to the new base color, as opposed to the original base color.
17. The method according to claim 15 wherein, determining the base color is performed by converting the predetermined region of the color image to a predetermined color space comprising a plurality of color channels; and establishing and combining are performed upon the predetermined region for each color channel of the plurality of color channels.
18. The method according to claim 15 wherein, establishing at least one shading parameter comprises establishing the at least one shading parameter for a color component of a predetermined color space representation of the colors in the predetermined region showing a largest variation within the predetermined region.
19. The method according to claim 15 further comprising:
determining a plurality of other regions of the color image by implementing the ambient/diffuse shading model using the processing unit;
establishing for each other region of the plurality of other regions at least one shading parameter by implementing the ambient/diffuse shading model using the processing unit; and
generating for each other region of the plurality of other regions a new other region of the color image by either combining the at least one shading parameter for that other region of the plurality of other regions with a new base color defined in a predetermined color space by a set of neutral values or not adding a new base color into an energy equation associated with the ambient/diffuse shading model when combining the new base color with the at least one shading parameter for the predetermined region of the color image.