Image demosaicer and method

An image demosaicer for demosaicing a raw image captured by an image sensor that includes a pixel array and a Bayer-pattern color-filter array (CFA) having a plurality of red color filters CFr, green color filters CFg, and blue color filters CFb each covering a respective one of a plurality of m×n pixel sub-arrays of the pixel array, the pixel array including a plurality of pixels p(x,y)α located at a respective one of a plurality of coordinates (x,y)α, and beneath a color filter CFα, and each generating a respective one of a plurality of primary pixel-values Bα(x,y)α, where a is one of r, g, and b:

• a memory storing non-transitory computer-readable instructions and adapted to store the raw image;
• a microprocessor adapted to execute the instructions to:
• horizontally-interpolate a green channel, of the raw image, formed of primary pixel-values Bg(x,y)g of the plurality of primary pixel-values Bα(x,y)α, to yield a horizontally-interpolated green channel that includes both primary pixel-values Bg(x,y)g and non-primary pixel-values Igh(x,y)r,b;
• modify each non-primary pixel-value Igh(x,y)r,b by a plurality of horizontally-neighboring non-primary pixel-values Igh(x,y)r,b, to yield a refined horizontally-interpolated green channel;
• vertically-interpolate the green channel to yield a vertically-interpolated green channel that includes both primary pixel-values Bg(x,y)g and non-primary pixel-values Ig(x,y)r,b;
• modify each non-primary pixel-value Igv(x,y)r,b by a plurality of vertically-neighboring non-primary pixel-values Igv(x,y)r,b, to yield a refined vertically-interpolated green channel;
• generate a full-resolution green channel from the refined horizontally-interpolated green channel, refined vertically-interpolated green channel, a horizontal-gradient of the horizontally-interpolated green channel, and a vertical-gradient of the vertically-interpolated green channel;
• generate a full-resolution red channel by determining a plurality of non-primary red pixel-values Ir (xt, yt)g,b, each corresponding to a respective one of the plurality of coordinates (xt, yt)g,b, from a local-red mean value of neighboring red primary pixel-values Br(x,y)r and the full-resolution green channel;
• generate a full-resolution blue channel by determining a plurality of non-primary blue pixel-values Ib(xt, yt)g,r, each corresponding to a respective one of the plurality of coordinates (xt, yt)g,r, from a local-blue mean value of neighboring blue primary pixel-values Bb (x,y)b and the full-resolution green channel;
• and
• combine the full-resolution red channel, the full-resolution green channel, and the full-resolution blue channel to yield a demosaiced raw image.