It's still a bit unclear as to what look you're going for.
Would you be able to link us to an image of the look you're trying to achieve? Or tell us what you're using it for, so we could better understand what you want.
Do you want it to be at a lower resolution/look pixelated? A specific number of colours?
There are a lot of ways you can do stuff like that. What image editors do you have? Many will have things like the Posterize tool, or you can push the contrast on the image right up... (For reducing the number of colours used in the image.)
Again, it's hard to offer a solution when I'm not entirely sure of the effect you want.
Would you be able to link us to an image of the look you're trying to achieve? Or tell us what you're using it for, so we could better understand what you want.
Do you want it to be at a lower resolution/look pixelated? A specific number of colours?
There are a lot of ways you can do stuff like that. What image editors do you have? Many will have things like the Posterize tool, or you can push the contrast on the image right up... (For reducing the number of colours used in the image.)
Again, it's hard to offer a solution when I'm not entirely sure of the effect you want.