A method for processing image data in a camera, said camera being configured to receive light and generate image data using an image sensor having an associated filter array (50, 51), said image sensor including an array of pixels, each of which correspond to a filter element in the filter array (50, 51), so that the pixel has a spectral response at least partly defined by a corresponding filter element; wherein the filter array includes a pattern of wideband filter elements and at least two types of narrowband filter elements (R, G, B); the method including: generating a wideband image (60, 90) comprising a wideband filter element value for each pixel of the image sensor, each wideband filter element value being calculated by applying a first (50-1, 51-1) or second (50-2, 51-2) filter kernel to its corresponding pixel of the image sensor; wherein the first filter kernel (50-1, 51-1) is applied if the pixel corresponds to a wideband filter element and the second filter kernel (50-2, 51-2) is applied if the pixel corresponds to a narrowband filter element (R, G, B); generating a narrowband luminance image (70, 100) comprising a narrowband filter element value for each pixel of the image sensor, the narrowband filter element values calculated using only pixels corresponding to narrowband filter elements (R, G, B); generating a low-pass-filtered wideband luminance image (80, 110) comprising a low-pass-filtered wideband filter element value for each pixel of the image sensor, the low-pass-filtered wideband filter element values being calculated using only pixels corresponding to wideband filter elements, wherein the narrowband filter element values of the narrowband luminance image (70, 100) and the wideband filter element values of the low-pass-filtered wideband luminance image (80, 110) are calculated using the same third (50-3, 51-3) and fourth (50-4, 51-4) filter kernels; and wherein: generating the narrowband luminance image (70, 100) includes applying the third filter kernel (50-3, 51-3) to a pixel if the pixel corresponds to a wideband filter element and applying the fourth filter kernel (50-4, 51-4) if the pixel corresponds to a narrowband filter element (R, G, B); and generating the low-pass-filtered wideband luminance image (80, 110) includes applying the third filter kernel (50-3, 51-3) to a pixel if the pixel corresponds to a narrowband filter element (R, G, B) and applying the fourth filter kernel (50-4, 51-4) if the pixel corresponds to a wideband filter element. generating a wideband image (60, 90) comprising a wideband filter element value for each pixel of the image sensor, each wideband filter element value being calculated by applying a first (50-1, 51-1) or second (50-2, 51-2) filter kernel to its corresponding pixel of the image sensor; wherein the first filter kernel (50-1, 51-1) is applied if the pixel corresponds to a wideband filter element and the second filter kernel (50-2, 51-2) is applied if the pixel corresponds to a narrowband filter element (R, G, B); generating a narrowband luminance image (70, 100) comprising a narrowband filter element value for each pixel of the image sensor, the narrowband filter element values calculated using only pixels corresponding to narrowband filter elements (R, G, B); generating a low-pass-filtered wideband luminance image (80, 110) comprising a low-pass-filtered wideband filter element value for each pixel of the image sensor, the low-pass-filtered wideband filter element values being calculated using only pixels corresponding to wideband filter elements, wherein the narrowband filter element values of the narrowband luminance image (70, 100) and the wideband filter element values of the low-pass-filtered wideband luminance image (80, 110) are calculated using the same third (50-3, 51-3) and fourth (50-4, 51-4) filter kernels; and wherein: generating the narrowband luminance image (70, 100) includes applying the third filter kernel (50-3, 51-3) to a pixel if the pixel corresponds to a wideband filter element and applying the fourth filter kernel (50-4, 51-4) if the pixel corresponds to a narrowband filter element (R, G, B); and generating the low-pass-filtered wideband luminance image (80, 110) includes applying the third filter kernel (50-3, 51-3) to a pixel if the pixel corresponds to a narrowband filter element (R, G, B) and applying the fourth filter kernel (50-4, 51-4) if the pixel corresponds to a wideband filter element. generating the narrowband luminance image (70, 100) includes applying the third filter kernel (50-3, 51-3) to a pixel if the pixel corresponds to a wideband filter element and applying the fourth filter kernel (50-4, 51-4) if the pixel corresponds to a narrowband filter element (R, G, B); and generating the low-pass-filtered wideband luminance image (80, 110) includes applying the third filter kernel (50-3, 51-3) to a pixel if the pixel corresponds to a narrowband filter element (R, G, B) and applying the fourth filter kernel (50-4, 51-4) if the pixel corresponds to a wideband filter element.