transmogrify

#!/usr/bin/env node
'use strict';

var file,
  fs = require('fs'),
  PNG = require('png-js'),
  argv = require('minimist')(process.argv.slice(2)),
  usage = 'Usage: \ttransmogrify <filename> [-f] [-h]\nHelp: \ttransmogrify draws a png to your console.\nOptions:\n\t-f --fit\tFit the image to the console size.\n\t-h --help\tRenders this message.',
  kdi = '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'.match(/.{1,2}/g).map(function(n) { return parseInt(n,16) }),
  colors = '000000800000008000808000000080800080008080c0c0c0808080ff000000ff00ffff000000ffff00ff00ffffffffff00000000005f0000870000af0000d70000ff005f00005f5f005f87005faf005fd7005fff00870000875f0087870087af0087d70087ff00af0000af5f00af8700afaf00afd700afff00d70000d75f00d78700d7af00d7d700d7ff00ff0000ff5f00ff8700ffaf00ffd700ffff5f00005f005f5f00875f00af5f00d75f00ff5f5f005f5f5f5f5f875f5faf5f5fd75f5fff5f87005f875f5f87875f87af5f87d75f87ff5faf005faf5f5faf875fafaf5fafd75fafff5fd7005fd75f5fd7875fd7af5fd7d75fd7ff5fff005fff5f5fff875fffaf5fffd75fffff87000087005f8700878700af8700d78700ff875f00875f5f875f87875faf875fd7875fff87870087875f8787878787af8787d78787ff87af0087af5f87af8787afaf87afd787afff87d70087d75f87d78787d7af87d7d787d7ff87ff0087ff5f87ff8787ffaf87ffd787ffffaf0000af005faf0087af00afaf00d7af00ffaf5f00af5f5faf5f87af5fafaf5fd7af5fffaf8700af875faf8787af87afaf87d7af87ffafaf00afaf5fafaf87afafafafafd7afafffafd700afd75fafd787afd7afafd7d7afd7ffafff00afff5fafff87afffafafffd7afffffd70000d7005fd70087d700afd700d7d700ffd75f00d75f5fd75f87d75fafd75fd7d75fffd78700d7875fd78787d787afd787d7d787ffd7af00d7af5fd7af87d7afafd7afd7d7afffd7d700d7d75fd7d787d7d7afd7d7d7d7d7ffd7ff00d7ff5fd7ff87d7ffafd7ffd7d7ffffff0000ff005fff0087ff00afff00d7ff00ffff5f00ff5f5fff5f87ff5fafff5fd7ff5fffff8700ff875fff8787ff87afff87d7ff87ffffaf00ffaf5fffaf87ffafafffafd7ffafffffd700ffd75fffd787ffd7afffd7d7ffd7ffffff00ffff5fffff87ffffafffffd7ffffff0808081212121c1c1c2626263030303a3a3a4444444e4e4e5858586262626c6c6c7676768080808a8a8a9494949e9e9ea8a8a8b2b2b2bcbcbcc6c6c6d0d0d0dadadae4e4e4eeeeee'.match(/.{1,6}/g).map(function(n) { return parseInt(n,16) });

function h2r(hex) {
  var r = hex >> 16,
    g = hex >> 8 & 0xFF,
    b = hex & 0xFF;
  return [r, g, b];
}

function d(x, y) {
  x = x.slice ? x : h2r(x);
  y = y.slice ? y : h2r(y);
  return Math.abs(x[0] - y[0]) + Math.abs(x[1] - y[1]) + Math.abs(x[2] - y[2]);
}

function nn(node, value, depth, closest) {
  var color, ri, axis, branches, dist;
  if (closest === null) {
    closest = {idx: 0, dist: 0xFFFFFF};
  }
  color = h2r(colors[kdi[node]]);
  ri = node * 2 + 2;
  if (ri < kdi.length) {
    axis = depth % 3;
    branches = value[axis] < color[axis] ? [ri - 1, ri] : [ri, ri - 1];
    nn(branches[0], value, depth + 1, closest);
    if (Math.abs(value[axis] - color[axis]) < closest.dist) {
      nn(branches[1], value, depth + 1, closest);
    }
  } else {
    dist = d(color, value);
    if (dist < closest.dist) {
      closest.dist = dist;
      closest.idx = node;
    }
  }
  return kdi[closest.idx];
}

function fit(png, pixels) {
  var px = pixels;

  var cw = process.stdout.columns / 2 - 2;
  var ch = process.stdout.rows - 2;

  if(cw < png.width || ch < png.height) {
    var scale = Math.min(cw / png.width, ch / png.height);
    var r = [], g = [], b = [], counts = {};

    var pw = Math.floor(png.width * scale);
    var ph = Math.floor(png.height * scale);

    for (i = 0; i < pixels.length; i += 4) {
      var ri = i / 4;
      var col = Math.floor(scale * (ri % png.width));
      var row = Math.floor(scale * (ri / png.width));

      var idx = row * pw + col; 

      if(!r[idx]) {
        r[idx] = g[idx] = b[idx] = counts[idx] = 0;
      }
      r[idx] += pixels[i];
      g[idx] += pixels[i + 1];
      b[idx] += pixels[i + 2];
      counts[idx] += 1;
    }
    px = [];
    png.width = pw;
    png.height = ph;
    for(var i = 0; i < r.length; i++) {
      px.push(r[i] / counts[i], g[i] / counts[i], b[i] / counts[i], i % pw == pw - 1 ? 0 : 255);
    }
  }
  return px;
}

if(argv.h || argv.help || argv._.length < 1) {
  console.log(usage);
  process.exit();
}

file = process.argv[2];

fs.readFile(file, function (err, file) {
  var png;
  if (err) {
    throw 'Whoops: ' + err;
  }
  png = new PNG(file);
  
  png.decode(function (pixels) {
    if(argv.f || argv.fit) {
      pixels = fit(png, pixels);
    }
    var i, row = [], l = '\x1B[48;5;', r = 'm  \x1B[49m';
    for (i = 0; i < pixels.length; i += 4) {
      if (row.length === png.width) {
        console.log(row.join(''));
        row = [];
      }
      if (!pixels[i + 3]) {
        row.push('  ');
      } else {
        row.push(l + nn(0, [pixels[i], pixels[i + 1], pixels[i + 2]], 0, null) + r);
      }
    }
    if (row.length === png.width) {
      console.log(row.join(''));
    }
  });
});