main.go

package main

import (
	"image/color"
	"math/rand"

	"github.com/mmcloughlin/globe"
)

func Draw(c color.Color, filename string) error {
	lat, lng := 51.453349, -2.588323
	g := globe.New()
	g.DrawGraticule(10.0)
	for i := 0; i < 1000; i++ {
		plat := lat + 20.0*(rand.Float64()-0.5)
		plng := lng + 20.0*(rand.Float64()-0.5)
		g.DrawDot(plat, plng, 0.1, globe.Color(c))
	}
	g.CenterOn(lat, lng)
	return g.SavePNG(filename, 400)
}

func main() {
	Draw(color.NRGBA{255, 0, 0, 128}, "nrgba.png")
	Draw(color.RGBA{255, 0, 0, 128}, "rgba.png")
}

nrgba.png

RGBA.md

Golang's color.RGBA seems to produce some odd artifacts.

rgba.png