demo-04-20/demo.lua

local bitmap = require'bitmap' --used to read its content

function int_exa(nb)
  output = "0123456789abcdef"
  first_digit = 0
  while nb > 15 do
    nb = nb - 16
    first_digit = first_digit + 1
  end
  return output:sub(first_digit + 1, 1)..output:sub(nb + 1, 1)
end

io.write("from casioplot import set_pixel, show_screen as S, R\n")

do --open image
  local cairo = require'cairo' --used to open the file
  local image = cairo.load_png(arg[1])
  image_infos = {width = image:width(), height = image:height()}
  image_bitmap = image:bitmap()
end
local getpixel, setpixel = bitmap.pixel_interface(image_bitmap)

pallet = {} --will store colors
pallet_last = 0


for j = 1, image_infos.height, 1 do
  for i = 1, image_infos.width, 1 do
    r, g, b = getpixel(i, j)
    if not pallet[r.." "..g.." "..b] then
      pallet[r.." "..g.." "..b] = pallet_last
      pallet_last = pallet_last + 1
    end
    io.write(int_exa(pallet[r.." "..g.." "..b]))
  end
end

io.write("\nR()")