Apple TV: Change from vivid or dynamic picture setting for best color display
Some televisions include a picture setting labeled "Vivid" or "Dynamic" (which may be set as the default setting). This setting can be useful if the TV is in a brightly lit room, but may affect the colors displayed.
Apple TV (1st generation), Apple TV (2nd generation)
If you're not satisfied with the color produced by Apple TV, try changing your television's picture settings, or manually adjust the picture. Check the documentation that came with your TV for more information about adjusting the picture settings.
To learn about adjusting HDMI video brightness in Apple TV, see HDMI video is too dark or too light.