mengto-dither-background

name	mengto-dither-background
description	Create a dark monochrome procedural background with enlarged square pixels and visible Bayer-style ordered dithering. Use when a page needs an atmospheric near-black dither field, broad organic waves or cloud masses, and restrained gray-white highlights behind framed UI, hero content, or data overlays.

Dither Background

Use When

• A dark interface needs an atmospheric monochrome background layer.
• The visual should show enlarged square pixels and visible ordered dithering.
• The design calls for organic waves, cloud-like masses, or procedural depth without colorful gradients.
• The background should support framed UI, hero content, or data overlays.

Visual Target

• Near-black base with charcoal midtones, soft gray buildup, and occasional white highlights.
• Clearly visible square pixel cells, not tiny film grain.
• 4x4 Bayer-style dither pattern or equivalent ordered thresholding.
• Broad organic waves or cloud-like masses, not random TV noise.
• Vignetted edges so the brighter mass sits centrally or off-axis.

HTML And CSS

<canvas class="dither-background" data-dither-background></canvas>

.dither-background {
  position: fixed;
  inset: 0;
  z-index: 0;
  width: 100vw;
  height: 100vh;
  background: #030303;
  pointer-events: none;
}

.page-content {
  position: relative;
  z-index: 1;
}

Canvas Recipe

Use a real canvas when motion or procedural depth is needed.

const BAYER_4X4 = [
   0,  8,  2, 10,
  12,  4, 14,  6,
   3, 11,  1,  9,
  15,  7, 13,  5,
].map((value) => (value + 0.5) / 16);

function smoothstep(edge0, edge1, value) {
  const t = Math.max(0, Math.min(1, (value - edge0) / (edge1 - edge0)));
  return t * t * (3 - 2 * t);
}

function noise2(x, y) {
  const value = Math.sin(x * 127.1 + y * 311.7) * 43758.5453123;
  return value - Math.floor(value);
}

function valueNoise(x, y) {
  const ix = Math.floor(x);
  const iy = .(y);
   fx = x - ix;
   fy = y - iy;
   ux = fx * fx * ( -  * fx);
   uy = fy * fy * ( -  * fy);

   a = (ix, iy);
   b = (ix + , iy);
   c = (ix, iy + );
   d = (ix + , iy + );
   (
    a * ( - ux) * ( - uy) +
    b * ux * ( - uy) +
    c * ( - ux) * uy +
    d * ux * uy
  );
}

 () {
   value = ;
   amplitude = ;
   frequency = ;

   ( octave = ; octave < ; octave++) {
    value += (x * frequency, y * frequency) * amplitude;
    frequency *= ;
    amplitude *= ;
  }

   value;
}

 () {
   (!canvas)   {};

   ctx = canvas.(, { :  });
   (!ctx)   {};

   reduceMotion = .().;
   cell = options. || ;
   maxDpr = options. || ;
   width = ;
   height = ;
   cols = ;
   rows = ;
   rafId = ;

   palette = options. || [
    [, , ],
    [, , ],
    [, , ],
    [, , ],
    [, , ],
    [, , ],
  ];

   () {
     dpr = .(. || , maxDpr);
    width = .(, .);
    height = .(, .);
    canvas. = .(width * dpr);
    canvas. = .(height * dpr);
    canvas.. = ;
    canvas.. = ;
    ctx.(dpr, , , dpr, , );
    cols = .(width / cell);
    rows = .(height / cell);
  }

   () {
     nx = (x / cols - ) * ;
     ny = (y / rows - ) * ;
     distance = .(nx * nx *  + ny * ny * );
     vignette =  - (, , distance);
     drift = reduceMotion ?  : time * ;

     wave =
      .(nx *  + ny *  + drift) *  +
      .(nx * - + ny *  - drift * ) * ;
     cloud = (nx *  + drift * , ny *  - drift * );
     ridge = (, , cloud + wave);
     offAxisMass = (, , .(nx + , ny - ));

     .(, .(, ridge * vignette *  + offAxisMass * ));
  }

   () {
     seconds = time * ;
    ctx. = ;
    ctx.(, , width, height);

     ( y = ; y < rows; y++) {
       ( x = ; x < cols; x++) {
         threshold = [(y % ) *  + (x % )];
         brightness = (x, y, seconds);
         stepped = .(.(, .(, brightness + threshold * )) * palette.);
         color = palette[.(palette. - , stepped)];
        ctx. = ;
        ctx.(x * cell, y * cell, cell, cell);
      }
    }

     (!reduceMotion) rafId = (render);
  }

   () {
    (rafId);
    ();
    ();
  }

  ();
  ();
  .(, handleResize);

    {
    (rafId);
    .(, handleResize);
  };
}

 cleanupDither = (
  .(),
  {
    : ,
    : ,
  }
);

Tuning Knobs

• Cell size: 5px-10px; larger cells make the Bayer matrix more legible.
• Palette: near-black, charcoal, soft gray, rare white highlights only.
• Shape: tune wave, cloud, ridge, and offAxisMass to create broad masses.
• Vignette: increase edge falloff when foreground readability needs more quiet.
• Motion: keep drift slow; use low time multipliers and avoid flicker.
• Performance: increase cellSize or cap maxDpr before simplifying the field.

Composition Notes

• Put the canvas behind the interface with pointer-events: none.
• Use it as atmosphere behind framed UI, hero copy, or data overlays.
• Keep foreground contrast controlled and typography clean.
• Let one main bright mass define the composition; avoid even full-screen brightness.

Avoid

• Rainbow gradients, colorful noise, or soft blurry blobs without dither structure.
• Tiny grain or static-like speckle where the square matrix disappears.
• Bright full-screen white noise that competes with foreground type.
• Random per-frame noise that flickers instead of drifting.
• Covering the entire viewport with equally bright cells.

Quick Checks

• The square Bayer pattern is visible from normal viewing distance.
• The field forms broad organic waves or cloud masses.
• The palette stays monochrome and restrained.
• Edges recede into near-black.
• Foreground UI remains readable without heavy overlays.