It ended up working! Thanks for that!

However, I do have three questions.

1. Keep the ratio in what area? Because 21800 is not twice as much as 10800. So, is the ratio there? Or is it in 21600 or 10800?
2. How do you retain the colors? Because when saved it as a PNG, it lost the color, and it became black and white.
3. If you are able to make the colors stay, can I change the color palette itself? Specifically in this image?

Topography.jpg

And this is the color legend.

Topography_legend.png