= canvas.getContext("2d");
    // background
    context.fillStyle="#eeeeee";
    context.fillRect(0, 0, w, h);

    // pixels
    var pixel_field = context.createImageData(w, h);
    for (var i = 0; i < pixel_field.data.length; i += 4) {
        var on_canvas_i = Math.floor(Math.floor(i / 4) / w);
        var on_canvas_j = Math.floor(i / 4) % w;
        var in_pixels_i = Math.floor(on_canvas_i / pixel_size);
        var in_pixels_j = Math.floor(on_canvas_j / pixel_size);
        if(pixels[in_pixels_i][in_p