We don’t store color data in full precision usually. People aren’t sensitive to all colors equally, the less sensitive the eye is to a particular color the more efficiently you can store it.

You can also typically discard high frequency data in your color channels. So not only are you not storing full precision data, you also don’t need to store roughly a third of the frequency bins. You can think of this like cropping the image but in the frequency domain. The data saving are identical to cropping the image but visually imperceptible.