Use png and IDK I don’t remember which cmd line soft but it stripped out unused colors and compressed images like that one hard.
That, without the red lines and circles, and without jpeg jitter should be like 1kb. Or less less.
Now, as an oldtimer, when you load that 1kb image up, it will still take like 640x320 bytes (it was all 8bit) so 200KB of RAM. But back in the day I guess it was more like the original GB 160x144 so 22.5KB RAM needed to show that image.
Did it work like that?
No, because cartridges didn’t have a lot of space, and the consoles didn’t have much RAM, so you used tiles. You had a tile map image, each tile was 8x8 pixels pointing to a palette (so you could use 4-bits for the color. More or less so, there were a lot of ‘modes’). Each tile had a number and your screen was some 20x18 tiles x 1 byte numbers, designing the ‘tile’ to be shown at that particular position of the screen.
All done by hardware so way fast!
To make the scrolling run you had a ‘delta’ pixels to slightly move the “screen” around.