The new 18.104.22.168 software update that is rolling out to the Amazon Fire TV Stick 4K, Fire TV Cube, and Fire TV 3 (pendant) is adding a new third “Auto” option to the existing Color Format setting, which previously only allowed customers to select from “RGB” or “YCbCr.” When set to Auto, which is the new default configuration, the Fire TV may decide to switch its color format setting if one is better than the other for your particular TV model.
The Color Format setting, first introduced with the Fire TV 3, essentially lets you decide if you want the Fire TV to handle the conversion to RGB, in which case you would set the color format setting to RGB, or if you want your TV to handle the conversion to RGB, in which case you would set the Fire TV’s color format to YCbCr. The new Auto setting lets the Fire TV decide which is best.
The YCbCr color space is used by the media industry to optimize a video signal by devoting more information to the parts of the image that the human eye can better perceive. Before the optimized video signal can be displayed on the RGB pixels of a TV, it must be converted to an RGB color space. Some TVs will produce a better picture if they receive a YCbCr video signal and convert it to RGB themselves.
I’m told that some TVs, particular those manufactured in 2010, 2011, and 2012, do not handle YCbCr reliably, despite claiming support. This new Auto setting for Color Format gives the Fire TV the flexibility to switch settings for these troublesome TVs. Interestingly, the automatic switch will only occur if you also have the Fire TV’s Match Original Frame Rate setting enabled, which you can learn much more about here. If your Fire TV is set to match the native frame rate of the video being played, and the Color Format setting is set to Auto, the Fire TV will pick the appropriate option between RGB and YCbCr for your TV. Both of these options can be found under the Settings > Display & Sound > Display menu.