My display is currently outputting 8-bit color without dithering. This is the default behavior of an Nvidia GPU on Windows. This can also be seen in some games and images. My monitor is also limited to 8-bit but does support both limited and full dynamic range.
There are some guides online which show how to enable dithering on the output but I'm not certain that I will be able to observe these changes if the source image or game I'm using is itself an undithered, banded output.
What is a reliable source that I can observe to confirm that the output I'm viewing is dithered?
Nvidia control panel:
Example of mist from Skyrim in-game menu (brightness enhanced):
1 Answer
To answer the question directly "how can I tell":
At the resolution and color depth in your example, dithering noise will be visible and you know there is dithering.
If you want to know if the display itself is dithering something, you can use different hardware with the same source to rule out the display device.
Dithering is basically the addition of noise, either random noise or more informed value choices at transitions in order to smooth or hide those transitions. Think of it as intentional errors to cover for unwanted ones.
In the context you are talking about, banding happens because of lack of precision in the numeric representation of RGB channel brightness levels and what might have been a real-number value (2.2) is being quantized to an integer (2).
A common way to deal with banding is to introduce random noise and then use Temporal Anti-alaising (TAA). TAA can hide noise quite well, but may appear blurry without an additional sharpening pass.
If you are using a rendering mod on Skyrim (or any other game), bear in mind that the Skyrim load screens and menus might not be rendered the same as the game scenes proper.
Outside of the possibility of different shaders being used, the mist in a menu may be a series of pre-baked sprites overlaid and animated where the main game loop may render mist in the scenes as a live calculation at 16bpp precision and then dithered to 8 for presentation. This is a also common graphic design technique for bandless gradients.
"(brightness enhanced)"
In my personal experience, excessive banding in games, though unavoidable (at least, until recently) was usually an indicator of bad gamma or brightness settings in either the game or the hardware. Very often both. Even if one actually earnestly adjusts the levels of a game (such as when the game prompts them upon staring a new campaign), very few people actually calibrate their monitors. Calibration devices can be found for rent at e.g. photo shops.
