Javascript BMP-To-Script Converter for Khan Academy

function khan(filename,scriptname,squaresize) -- Type in your luasocket or whatever "khan(Name of image,name of
                          -- created script,squaresize)" Without the quotes. It works well if pic
                          -- is less than 200x200 pix. It only works with 24-bit BMPs though.
                          -- Squaresize: Size of the pixels.
local file=io.open(filename,'rb')
local f=io.open(scriptname,'w')
file:seek('set',18)
local y=string.byte(file:read(1))+string.byte(file:read(1))*256+string.byte(file:read(1))*65536+string.byte(file:read(1))*16777216
local x=string.byte(file:read(1))+string.byte(file:read(1))*256+string.byte(file:read(1))*65536+string.byte(file:read(1))*16777216
file:seek('set',54)
local r,g,b=0,0,0
for j=0,x-1 do
 for i=0,y-1 do
  b,g,r=string.byte(file:read(1)),string.byte(file:read(1)),string.byte(file:read(1))
  if i*squaresize<401 and (x-j)*squaresize<401 then
   f:write("stroke(",r,",",g,",",b,");\n")
   f:write("rect(",i*squaresize,",",(x-j)*squaresize,",",squaresize,",",squaresize,");\n")
end
  end
 end
 for i=1,y%4 do file:read(1) end
file:close()
end