Digital image processing for calculating a missing color value
A spectrally mosaiced digital image is provided with missing color data imputed for each pixel. Circuitry is provided that is configured to perform at least a portion of the calculations related to demosaicing a high dynamic range image.
1. An apparatus comprising:
a processing circuit for calculating a missing color value for a pixel location using an interpolation equation that is selected based on a direction of an edge feature in an image, wherein calculations performed using said interpolation equation are primarily based on values of eight spectrally mosaiced filtered pixels that are immediate neighbors of said pixel location and that include neighboring pixels with a spectral filter color that is different from said missing color value,
where said interpolation equation is N 22 =(N 11 +N 13 +N 31 +N 33 )/4+(G 12 −G 21 −G 23 +G 32 )/2, wherein N 22 is a non-green missing color value for said pixel location; N 11 , N 13 , N 31 , and N 33 are color values of neighboring pixels with a non-green spectral filter color; and G 12 , G 21 , G 23 , and G 32 are color values of neighboring pixels with a green spectral filter color.
2. An image processing apparatus, comprising:
a processing circuit for calculating a first missing color value for a pixel location using an interpolation equation that is selected based on a direction of an edge feature in an image, wherein calculations performed using said interpolation equation are primarily based on values of eight spectrally mosaiced filtered pixels that are immediate neighbors of said pixel location and wherein said calculations include the values of neighboring pixels with a spectral filter color that is different from said first missing color value,
where said interpolation equation is selected from amongst at least one of the following equations:
N 22 =( N 11 +N 13 +N 31 +N 33 )/4+( G 12 −G 21 −G 23 +G 32 )/2;
N 22 =( N 11 +N 13 +N 31 +N 33 )/4+(− G 12 +G 21 +G 23 −G 32 )/2;
N 22 =( N 21 +N 23 )/2+(− G 11 −G 13 −G 31 −G 33 +4 G 22 )/4;
N 22 =N 23 +(− G 13 −G 33 +2 G 22 )/4;
N 22 =N 21 +(− G 11 −G 31 +2 G 22 )/4;
N 22 =( N 12 +N 32 )/2+(− G 11 −G 13 −G 31 −G 33 +4 G 22 )/4;
N 22 =N 32 +(− G 31 −G 33 +2 G 22 )/4; and
N 22 =N 21 +(− G 11 −G 13 +2 G 22 )/4,
Wherein: N 22 is a non-green missing color value for said pixel location; N 11 , N 13 , N 31 , and N 33 are color values of neighboring pixels with a non-green spectral filter color that is the same color as the first missing color; G 12 , G 21 , G 23 , and G 32 are color values of neighboring pixels with a green spectral filter color; N 21 and N 23 are interpolated color values of neighboring pixels with a non-green spectral filter color that is a different color from the first missing color; and G 11 , G 13 , G 31 , and G 33 are interpolated green color values of neighboring pixels with a non-green spectral filter color that is the same color as the first missing color, and G 22 is the green color value of the pixel location.
3. An apparatus as in claim 2 , wherein said pixel location has a green color filter.
4. An apparatus as in claim 2 , wherein said pixel location has a red color filter.
5. An apparatus as in claim 2 , wherein said pixel location has a blue color filter.