Extended horizontal definition is provided in a television system in which the wideband and narrowband chrominance components of a video signal are modulated for transmission by a subcarrier. The modulated wideband I chrominance component is filtered over a bandwidth that is antisymmetrical about the subcarrier frequency with an extended upper sideband to thereby entend the bandwidth that is available for transmission of the I chrominance component. The modulated I chrominance component is antisymmetrically filtered to enhance the relative amplitude in the extended portion of the upper sideband for transmission, and in a television receiver the modulated I chrominance component of a received video signal is filtered to have a relatively flat-response over the antisymmetrical bandwidth about the subcarrier frequency. Alternatively, the antisymmetrical filtering of the modulated I chrominance component to enhance the relative amplitude in the extended portion of the upper sideband may take place in the receiver. The I chrominance component is filtered prior to modulation over a bandwidth defined by 2.4 MHz above the subcarrier frequency and 1.5 MHz below the subcarrier frequency. The narrowband Q chrominance component is filtered prior to modulation over a bandwidth defined by 1.5 MHz above and below the subcarrier frequency