Sceptero

const extract = require('png-chunks-extract');
const fs = require('fs');
const zlib = require('zlib');

const chunks = extract(fs.readFileSync(process.argv[2]));
const ihdr = chunks[0].data;
const idat = chunks[1].data;
const width = (ihdr[0] << 24) + (ihdr[1] << 16) + (ihdr[2] << 8) + ihdr[3];
const blocksize = width * 3 + 1;