In some conventional video processing systems, the transition from standard definition television (SDTV) to high definition television (HDTV) requires that advanced set-top boxes and televisions handle both standard-definition and high-definition video content in a high-quality manner. Cross-chrominance is a phenomenon that occurs when a composite video signal is separated into its luma (Y) and chroma (Cr, Cb) components. Cross-chrominance generally reduces the perceived quality of a HDTV signal. In a digital implementation, a composite video signal at baseband or immediate frequency (IF) is typically digitized using an analog-to-digital (A/D) converter. In an IF sub-sampled implementation, the digitized IF signal is down-converted to baseband using, for example, a mixer and a vestigial side band (VSB) filter. The resulting baseband samples are processed by a video decoder (VDEC), which provides estimates of the originally transmitted luma and chroma components of the video signal. The VDEC may comprise a comb filter, which separates the baseband luma signal from the modulated chroma. Cross-chrominance occurs when the comb filter misinterprets a portion of the luma information in the video signal as chroma information. The misinterpretation may occur for a plurality of reasons. For example, misinterpretation may occur whenever the luma includes frequency components very close to the 3.58 MHz color sub-carrier used for chroma modulation and/or when high-frequency details in the picture cause few spatial correlations, such as in a 2-D case. Misinterpretation may also occur when a comb filter incorrectly discriminates 2-D/3-D, top line/bottom line and notch. In instances where cross-chrominance occurs in an area of the picture that is moving, it may be very difficult to determine the magnitude and phase of a corresponding cross-chrominance vector based on the estimated luma and chroma data received from the VDEC.
In addition to cross-chrominance artifacts, when the comb filter misinterprets chroma information in the video signal as luma information cross-luminance artifacts may occur. This artifact typically manifests itself as hanging dots which occur during a chroma transition. The magnitude of the cross-luminance is typically related to the magnitude of the cross-chrominance. Cross-luminance may also manifest itself as a softening of high-frequency edges that may be incorrectly interpreted as chroma information.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.