How Is a Computer Able to Store and Quickly Manipulate All the Data Required For A Computer Display?

Question

I did some quick math on how much data is contained on a screen at any given instant and I ended up with a number well beyond what I thought was possible. 256 colors for Red, Green, and Blue each define a pixel and there are currently 1920x1080 pixels on my screen so..256 x 256 x 256 x 1920 x 1080 bits = 4.35 Terabytes of dataObviously that would require more space than is on my desktop, let alone some Raspberry pi. So how do they do it? Any other resources anyone has for learning how displays work in general I'd love to have a look.

Answer 1

Your calculated assumption is bit wrong here. When multiplying 256*256*256, what you are actually doing is determining the possible combinations of colors for one pixel, but that's not what a display does. If it was, each picture you have would be in the terabytes!

Imagine each of the ~2 million pixels of your monitor (or a picture) being allocated a memory space to store color data. We could format the color data in a lot of efficient ways, but imagine we just have an integer that holds a number like RRRGGGBBB, so for a green pixel it would be 000256000. This takes up a mere 9 BYTES of data.

So 9 bytes for each of the 2 million pixels = 18 megabytes. Not that bad.

Also, images have other little tricks to reduce size. For example, if there is a red square in the image that is, let's say, 30 pixels * 30 pixels, each pixel won't redefine itself, but will just say "I'm the same color as the last pixel" which saves space.

EDIT: Also, if we chose to store the color data in individual binary bits instead of integers, we could define every color while only using about 3 bytes instead of 9