The digital image sensor, such as a charged coupled device (CCD), of a digital camera has a plurality of photo-sites arranged in a colored filtered array or pattern, such as a RGB Bayer pattern. In the RGB Bayer pattern, each photo-site is filtered so that it is receptive to either: red, green, blue, or some variation thereof. The type of colored filter array and digital imaging sensor varies typically based on the manufacture of the digital camera. For example, some color filtered arrays use a pattern of yellow, cyan, green, and magenta. Typically, the digital camera has an image pipeline that performs a demosaicing or de-Bayering process on the image, lens correction, and noise reduction. The image pipeline may then perform an RGB contrast and saturation “boost” on the image data before encoding the image into the YCbCr family of color spaces or other format suitable for displaying and viewing.
Various considerations must be addressed when processing a digital image obtained with a digital camera or other imaging device. One consideration involves preserving the spatial quality and the detail of the digital image, while another consideration involves sufficiently representing the color of the digital image. In many ways, these two considerations are interrelated.
One well-known problem with performing a color “boost” operation on a digital image is that it can often have an undesirable affect on areas of the image where skin tones are present. Specifically, skin tones appear to be especially susceptible to boost operations introducing visually unappealing artifacts to the image. For example, certain lighting conditions can give skin tones an over-saturated, unnatural look when boosted. The result is that skin tones appear to have a strong orange, yellow, magenta, or red glow-while the rest of the image appears normally.