• High-performance PNG encoder written in pure Lua with optional LuaJIT FFI backend.

LuaJIT is much faster and Lua is not recommended for production usage.

• Provides a lightweight raster pipeline (geometry, shapes).
• Supports RGB and RGBA color modes.
• Only requires bit library.
• This library does not perform any compression. Output files are uncompressed PNGs.

• Check examples folder for more examples.

luaPNG selects the default runner based on (require("luaPNG.init")).UsingJIT variable.

--- Encoding standart PNG.
local Image = require("luaPNG.init")

local png = Image.new(256, 256, "rgb")

for i = 1, 256*256*3 do
    png.Data[i] = math.random(0,255)
end

print(Image.UsingJIT)

png:save("Example256x256.png")
print("Done in: ", os.clock())

--- Encoding standart PNG and drawing rectangle.
local Image = require("luaPNG.init")
local img = Image.new(800, 600, "rgba")

img:add(Geometry.Rectangle{
    x = 0, y = 0,
    w = 300, h = 300,
    color = {220, 60, 60, 180}, -- RGBA
    mode = "fill"
})

img:save("Example800x600.png")
print("Done in:", os.clock())

• You can run benchmark/pure_lua_benchmark.lua and benchmark/ffipng_benchmark.lua files to run the benchmark.

It will give CSV file in benchmark/output/* folder.

• png.lua slows down or crashes when encoding large RGBA images.

• MIT License