Patent Document ID: 7990381
Application ID: 11514481
Patent Status: 1

Claim One:
1. A method for re-coloring a region of a color image comprising: determining an original base color in the region of the color image by implementing an ambient/diffuse shading model using a processing unit establishing at least one shading parameter in the region of the color image by implementing the ambient/diffuse shading model using the processing unit; 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 using the 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 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 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−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 =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 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.