const sharp = require('sharp');
const p = 'data/media/assets/e6/e64a43a218fa7471fb0713652d383736757a81c004ced24c920b142d265acf58.png';
const pts = {
  podloga_wnetrze_1: [1200, 700],
  podloga_wnetrze_2: [900, 900],
  sciana_wnetrze:    [1000, 480],
  sciana_cien:       [900, 1100],
  pas_przedni_tk:    [1200, 1250],
  siedzisko_spod_tk: [700, 400],
  podlokietnik_tk:   [1750, 850],
  siedzisko_prawe_tk:[2050, 1300],
  siedzisko_lewe_tk: [300, 500],
  listwa_drewno:     [520, 1000],
};
(async()=>{
  const meta = await sharp(p).metadata();
  const { data } = await sharp(p).removeAlpha().raw().toBuffer({resolveWithObject:true});
  const W = meta.width;
  const luma = (i)=> 0.2126*data[i*3]+0.7152*data[i*3+1]+0.0722*data[i*3+2];
  const R = 9; // okno 19x19
  for (const [name,[x,y]] of Object.entries(pts)) {
    let s=0, s2=0, n=0;
    for (let dy=-R;dy<=R;dy++) for (let dx=-R;dx<=R;dx++) {
      const v = luma((y+dy)*W + (x+dx)); s+=v; s2+=v*v; n++;
    }
    const mean=s/n, std=Math.sqrt(Math.max(0, s2/n-mean*mean));
    console.log(name.padEnd(20), `L=${mean.toFixed(0).padStart(4)}`, `std=${std.toFixed(1)}`);
  }
})();