/**
* Calculate histograms for each color channel for the given image
*/
function GetImageHistogram($image_file, $options, $histograms)
{
$histogram = null;
$ext = strripos($image_file, '.jpg');
if ($ext !== false) {
$histogram_file = substr($image_file, 0, $ext) . '.hist';
} else {
$ext = strripos($image_file, '.png');
if ($ext !== false) {
$histogram_file = substr($image_file, 0, $ext) . '.hist';
}
}
if (isset($histograms)) {
// figure out the timestamp for the video frame in ms
$ms = null;
if (preg_match('/ms_(?P<ms>[0-9]+)\\.(png|jpg)/i', $image_file, $matches)) {
$ms = intval($matches['ms']);
} elseif (preg_match('/frame_(?P<ms>[0-9]+)\\.(png|jpg)/i', $image_file, $matches)) {
$ms = intval($matches['ms']) * 100;
}
foreach ($histograms as &$hist) {
if (isset($hist['histogram']) && isset($hist['time']) && $hist['time'] == $ms) {
$histogram = $hist['histogram'];
break;
}
}
}
// See if we have the old-style histograms (separate files)
if (!isset($histogram) && !isset($options) && isset($histogram_file) && is_file($histogram_file)) {
$histogram = json_decode(file_get_contents($histogram_file), true);
if (!is_array($histogram) || !array_key_exists('r', $histogram) || !array_key_exists('g', $histogram) || !array_key_exists('b', $histogram) || count($histogram['r']) != 256 || count($histogram['g']) != 256 || count($histogram['b']) != 256) {
unset($histogram);
}
}
// generate a histogram from the image itself
if (!isset($histogram)) {
$im = imagecreatefromjpeg($image_file);
if ($im !== false) {
$width = imagesx($im);
$height = imagesy($im);
if ($width > 0 && $height > 0) {
// default a resample to 1/4 in each direction which will significantly speed up processing with minimal impact to accuracy.
// This is only for calculations done on the server. Histograms from the client look at every pixel
$resample = 8;
if (isset($options) && array_key_exists('resample', $options)) {
$resample = $options['resample'];
}
if ($resample > 2) {
$oldWidth = $width;
$oldHeight = $height;
$width = intval($width * 2 / $resample);
$height = intval($height * 2 / $resample);
$tmp = imagecreatetruecolor($width, $height);
fastimagecopyresampled($tmp, $im, 0, 0, 0, 0, $width, $height, $oldWidth, $oldHeight, 3);
imagedestroy($im);
$im = $tmp;
unset($tmp);
}
$histogram = array();
$histogram['r'] = array();
$histogram['g'] = array();
$histogram['b'] = array();
$buckets = 256;
if (isset($options) && array_key_exists('buckets', $options) && $options['buckets'] >= 1 && $options['buckets'] <= 256) {
$buckets = $options['buckets'];
}
for ($i = 0; $i < $buckets; $i++) {
$histogram['r'][$i] = 0;
$histogram['g'][$i] = 0;
$histogram['b'][$i] = 0;
}
for ($y = 0; $y < $height; $y++) {
for ($x = 0; $x < $width; $x++) {
$rgb = ImageColorAt($im, $x, $y);
$r = $rgb >> 16 & 0xff;
$g = $rgb >> 8 & 0xff;
$b = $rgb & 0xff;
// ignore white pixels
if ($r != 255 || $g != 255 || $b != 255) {
if (isset($options) && array_key_exists('colorSpace', $options) && $options['colorSpace'] != 'RGB') {
if ($options['colorSpace'] == 'HSV') {
RGB_TO_HSV($r, $g, $b);
} elseif ($options['colorSpace'] == 'YUV') {
RGB_TO_YUV($r, $g, $b);
}
}
$bucket = (int) (($r + 1.0) / 256.0 * $buckets) - 1;
$histogram['r'][$bucket]++;
$bucket = (int) (($g + 1.0) / 256.0 * $buckets) - 1;
$histogram['g'][$bucket]++;
$bucket = (int) (($b + 1.0) / 256.0 * $buckets) - 1;
$histogram['b'][$bucket]++;
}
}
}
}
imagedestroy($im);
unset($im);
}
if (!isset($options) && isset($histogram_file) && !is_file($histogram_file) && isset($histogram)) {
file_put_contents($histogram_file, json_encode($histogram));
}
}
return $histogram;
}
/**
* Calculate a RGB histogram excluding white pixels
*
* @param mixed $image_file
* @param mixed $ignoreWhite - bool - should white pixels be ignored
* @param mixed $colorSpace - string - RGB, HSV or YUV
*/
function Histogram($image_file, $ignoreWhite, $colorSpace = 'RGB')
{
global $viewport;
$histogram = null;
$nowhite = $ignoreWhite ? '.nowhite' : '';
$histogram_file = "{$image_file}{$nowhite}.{$colorSpace}.hist";
if (is_file($histogram_file)) {
$histogram = json_decode(file_get_contents($histogram_file));
} else {
$im = imagecreatefrompng($image_file);
if ($im !== false) {
$right = imagesx($im);
$bottom = imagesy($im);
$left = 0;
$top = 0;
if (isset($viewport)) {
$left = $viewport['x'];
$top = $viewport['y'];
$right = $left + $viewport['width'];
$bottom = $top + $viewport['height'];
}
$histogram = array(array(), array(), array());
$buckets = 256;
for ($i = 0; $i < $buckets; $i++) {
$histogram[0][$i] = 0;
$histogram[1][$i] = 0;
$histogram[2][$i] = 0;
}
for ($y = $top; $y < $bottom; $y++) {
for ($x = $left; $x < $right; $x++) {
$rgb = ImageColorAt($im, $x, $y);
$r = $rgb >> 16 & 0xff;
$g = $rgb >> 8 & 0xff;
$b = $rgb & 0xff;
// ignore white pixels
if (!$ignoreWhite || $r != 255 || $g != 255 || $b != 255) {
if ($colorSpace == 'HSV') {
RGB_TO_HSV($r, $g, $b);
} elseif ($colorSpace == 'YUV') {
RGB_TO_YUV($r, $g, $b);
}
$histogram[0][$r]++;
$histogram[1][$g]++;
$histogram[2][$b]++;
}
}
}
imagedestroy($im);
unset($im);
file_put_contents($histogram_file, json_encode($histogram));
}
}
return $histogram;
}