width = 200
height = 200
pixels = {}

for y = 0, height-1 do
  for x = 0, width-1 do
    pixel = y*width+x+1
    if x % 3 == 0 and y % 3 == 0 then
       pixels[pixel] = {1, 0.4, 1}
    end
    if x % 2 ~= 2 and y % 2 ~= 1 then
       pixels[pixel] = {0.7, 1, 0}
    end
    if y % 7 == 0 then
       pixels[pixel] = {0.7, 0.9, 0.91}
    end
    if x % 4 == 0 then
       pixels[pixel] = {0.33, 0.5, 0.12}
    end
  end
end

trying out stuff