url2ascii.php

#!/usr/bin/php
<?php

/**
 *  Calibration: depending on your fonts and terminal colors, you may want to change these
 */
global $PIXELS, $COLORS, $HSV_COLORS;

$YSCALE = 12;
$XSCALE = 5;

$COLORS = array(
    'd95136' => '1', // red
    'e953e9' => '5', // purple
    '6f4bf9' => '4', // blue
    '42c9d6' => '6', // cyan
    '38cb36' => '2', // green
    'bcbb36' => '3'  // yellow
);

$PIXELS = array(
    '0.9' => '▓',
    '0.8' => '▒',
    '0.7' => '░',
    '0.6' => '#',
    '0.5' => 'X',
    '0.4' => 'T',
    '0.3' => '>',
    '0.2' => '-',
    '0.1' => '.',
    '0' => ' '
);

if ($argc != 2) {
    echo "Missing URL";
    die(1);
}

foreach ($COLORS as $rgb => $code) {
    $r = hexdec($rgb[0].$rgb[1]);
    $g = hexdec($rgb[2].$rgb[3]);
    $b = hexdec($rgb[4].$rgb[5]);

    $hsv = rgb_to_hsv($r, $g, $b);
    $degrees = 60 * $hsv[0];
    $HSV_COLORS[$degrees] = $code;
}

ksort($HSV_COLORS);

$HSV_COLORS[360 + key($HSV_COLORS)] = current($HSV_COLORS);
#drop($HSV_COLORS);


$url = $argv[1];
if ($url == 'calibrate') {
    echo "These are your available colors. Please set the \$COLOR variable accordingly\n";
    foreach ($COLORS as $color) {
        echo "\033[0;3".$color."m▓▓▓▓▓▓▓▓▓▓  (3".$color.")\033[0m\n";
    }
    exit;
}

// Stolen from http://stackoverflow.com/a/13887939
function rgb_to_hsv($r, $g, $b) {
    $R = (int)$r;
    $G = (int)$g;
    $B = (int)$b;
    $key = sprintf("%x%x%x", $R, $G, $B);

    static $cache = array();
    if (! (isset($cache[$key]) && $out = $cache[$key])) {

       // Convert the RGB byte-values to percentages
        $R = ($R / 255);
        $G = ($G / 255);
        $B = ($B / 255);

        // Calculate a few basic values, the maximum value of R,G,B, the
        //   minimum value, and the difference of the two (chroma).
        $maxRGB = max($R, $G, $B);
        $minRGB = min($R, $G, $B);
        $chroma = $maxRGB - $minRGB;

        // Value (also called Brightness) is the easiest component to calculate,
        //   and is simply the highest value among the R,G,B components.
        // We multiply by 100 to turn the decimal into a readable percent value.
        $computedV = $maxRGB;

        // Special case if hueless (equal parts RGB make black, white, or grays)
        // Note that Hue is technically undefined when chroma is zero, as
        //   attempting to calculate it would cause division by zero (see
        //   below), so most applications simply substitute a Hue of zero.
        // Saturation will always be zero in this case, see below for details.
        if ($chroma == 0)
            return array(0, 0, $computedV);

        // Saturation is also simple to compute, and is simply the chroma
        //   over the Value (or Brightness)
        // Again, multiplied by 100 to get a percentage.
        $computedS = ($chroma / $maxRGB);

        // Calculate Hue component
        // Hue is calculated on the "chromacity plane", which is represented
        //   as a 2D hexagon, divided into six 60 degree sectors. We calculate
        //   the bisecting angle as a value 0 <= x < 6, that represents which
        //   portion of which sector the line falls on.
        if ($R == $minRGB)
            $h = 3 - (($G - $B) / $chroma);
        elseif ($B == $minRGB)
            $h = 1 - (($R - $G) / $chroma);
        else
            $h = 5 - (($B - $R) / $chroma);

        // After we have the sector position, we multiply it by the size of
        //   each sector's arc (60 degrees) to obtain the angle in degrees.
        $computedH = $h;

        $out = array($computedH, $computedS, $computedV);
    }
    return $out;
}


function see() {
    print_r(func_get_args());
}

function drop() {
    print_r(func_get_args());
    exit;
}

$image = file_get_contents($url);

if (! $image) {
	echo "Could not fetch image $url\n";
	die(1);
}
$img = imagecreatefromstring($image);


#imagefilter($img, IMG_FILTER_EDGEDETECT);
$image_width = imagesx($img);
$image_height = imagesy($img);

$ascii_w_h_scale = $XSCALE / $YSCALE;
$img_scale = $image_width/$image_height;

$target_width = get_tty_width();
$target_height = ($target_width * $ascii_w_h_scale) / ($img_scale);

$ascii_x_scale = $image_width / $target_width;
$ascii_y_scale = $image_height / $target_height;

function brightness_from_index($rgb, &$_r, &$_g, &$_b) {
    $r = (($rgb >> 16) & 0xFF);
    $g = (($rgb >> 8) & 0xFF);
    $b = (($rgb) & 0xFF);

    $_r += $r;
    $_g += $g;
    $_b += $b;

    $r /= 256;
    $g /= 256;
    $b /= 256;

    // based on perceived brightness
    $out = sqrt((0.241*$r*$r) + (0.691*$g*$g) + (0.068*$b*$b));

    return $out;
}

function get_tty_width() {
    $output = exec('tput cols');
    return $output;
}


function get_ascii_pixel($img, $x0, $x1, $y0, $y1) {
    global $HSV_COLORS, $PIXELS;
	$total = 0;
    $count = 0;

    $r = $g = $b = 0;

	for ($x = round($x0); $x < round($x1); $x++) {
		for ($y = round($y0); $y < round($y1); $y++) {
            $total += brightness_from_index(imagecolorat($img, $x, $y), $r, $g, $b);
            $count++;
		}
	}

    $r /= $count;
    $g /= $count;
    $b /= $count;

    $hsv = rgb_to_hsv($r, $g, $b);
    $hue = ($hsv[0] * 60) % 360;

    $color_distances = array();
    foreach ($HSV_COLORS as $_hue => $value) {
        $color_distances[$value] []= abs($hue - $_hue);
        $color_distances[$value] []= 360 - abs($hue - $_hue);
    }

    $color_distances = array_map('min', $color_distances);
    asort($color_distances);

    $nearest_hue = key($color_distances);
    next($color_distances);
    $next_nearest_hue      = key($color_distances);
    $next_nearest_distance = current($color_distances);

    $lightness = $hsv[2];
    if ($next_nearest_distance < 60 && $lightness < 0.8 && $lightness > 0.4) {
        $back_hue = $nearest_hue;
        $nearest_hue = $next_nearest_hue;
        $saturation_glyph = (string)min(round($hsv[2] * $hsv[1] * 5) / 10 + 0.5, 0.9);
    } else {
        $back_hue = ($lightness > 0.6) ? "7" : "0";
        $saturation_glyph = (string)min(round($hsv[2] * $hsv[1] * 10) / 10, 0.9);
    }

    $glyph = $PIXELS[$saturation_glyph];

    return "\033[0;3" . $nearest_hue . ";4".$back_hue."m".$glyph;

}

for ($y = 0; $y < $target_height - 1; $y++) {
	for ($x = 0; $x < $target_width - 1; $x++) {
		echo get_ascii_pixel($img, $x * $ascii_x_scale, ($x+1) * $ascii_x_scale, $y * $ascii_y_scale, ($y + 1) * $ascii_y_scale);
	}
	echo "\n";
}