Thumbnails with Face Detection in PHP - php

Question

My objective with this script is to make smart thumbnails. In my demo package, I am using two scripts from different sources.
To crop thumbnails (Source) - It totally works like native wordpress thumbnails
Face Detection in PHP (Source)
I am using the Face Detection to get the desired coordinates (where the face is) and then feed the coordinates to the crop script to make a thumbnail.
The problem is, if the Face Detection script does not find a face, it'd just time-out with the time out error
Fatal error: Maximum execution time of 30 seconds exceeded in...
I do not know how to come around this issue.
Is there any way to limit the amount of time the face detector takes to detect? I mean, if not found in like 15 seconds, return null.
Here's the Face Detection code:
<?php
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
//
// #Author Karthik Tharavaad
// karthik_tharavaad#yahoo.com
// #Contributor Maurice Svay
// maurice#svay.Com
namespace svay;
use Exception;
class FaceDetector
{
protected $detection_data;
protected $canvas;
protected $face;
private $reduced_canvas;
/**
* Creates a face-detector with the given configuration
*
* Configuration can be either passed as an array or as
* a filepath to a serialized array file-dump
*
* #param string|array $detection_data
*/
public function __construct($detection_data = 'detection.dat')
{
if (is_array($detection_data)) {
$this->detection_data = $detection_data;
return;
}
if (!is_file($detection_data)) {
// fallback to same file in this class's directory
$detection_data = dirname(__FILE__) . DIRECTORY_SEPARATOR . $detection_data;
if (!is_file($detection_data)) {
throw new \Exception("Couldn't load detection data");
}
}
$this->detection_data = unserialize(file_get_contents($detection_data));
}
public function faceDetect($file)
{
if (is_resource($file)) {
$this->canvas = $file;
} elseif (is_file($file)) {
//getting extension type (jpg, png, etc)
$type = explode(".", $file);
$ext = strtolower($type[sizeof($type)-1]);
$ext = (!in_array($ext, array("jpeg","png","gif"))) ? "jpeg" : $ext;
if ($ext == 'jpeg') {
$this->canvas = imagecreatefromjpeg($file);
} else if ($ext == 'png') {
$this->canvas = imagecreatefrompng($file);
} else if ($ext == 'gif') {
$this->canvas = imagecreatefromgif($file);
}
} else {
throw new Exception("Can not load $file");
}
$im_width = imagesx($this->canvas);
$im_height = imagesy($this->canvas);
//Resample before detection?
$diff_width = 320 - $im_width;
$diff_height = 240 - $im_height;
if ($diff_width > $diff_height) {
$ratio = $im_width / 320;
} else {
$ratio = $im_height / 240;
}
if ($ratio != 0) {
$this->reduced_canvas = imagecreatetruecolor($im_width / $ratio, $im_height / $ratio);
imagecopyresampled(
$this->reduced_canvas,
$this->canvas,
0,
0,
0,
0,
$im_width / $ratio,
$im_height / $ratio,
$im_width,
$im_height
);
$stats = $this->getImgStats($this->reduced_canvas);
$this->face = $this->doDetectGreedyBigToSmall(
$stats['ii'],
$stats['ii2'],
$stats['width'],
$stats['height']
);
if ($this->face['w'] > 0) {
$this->face['x'] *= $ratio;
$this->face['y'] *= $ratio;
$this->face['w'] *= $ratio;
}
} else {
$stats = $this->getImgStats($this->canvas);
$this->face = $this->doDetectGreedyBigToSmall(
$stats['ii'],
$stats['ii2'],
$stats['width'],
$stats['height']
);
}
return ($this->face['w'] > 0);
}
public function toJpeg()
{
$color = imagecolorallocate($this->canvas, 255, 0, 0); //red
imagerectangle(
$this->canvas,
$this->face['x'],
$this->face['y'],
$this->face['x']+$this->face['w'],
$this->face['y']+ $this->face['w'],
$color
);
header('Content-type: image/jpeg');
imagejpeg($this->canvas);
}
public function toJson()
{
return json_encode($this->face);
}
public function getFace()
{
return $this->face;
}
protected function getImgStats($canvas)
{
$image_width = imagesx($canvas);
$image_height = imagesy($canvas);
$iis = $this->computeII($canvas, $image_width, $image_height);
return array(
'width' => $image_width,
'height' => $image_height,
'ii' => $iis['ii'],
'ii2' => $iis['ii2']
);
}
protected function computeII($canvas, $image_width, $image_height)
{
$ii_w = $image_width+1;
$ii_h = $image_height+1;
$ii = array();
$ii2 = array();
for ($i=0; $i<$ii_w; $i++) {
$ii[$i] = 0;
$ii2[$i] = 0;
}
for ($i=1; $i<$ii_h-1; $i++) {
$ii[$i*$ii_w] = 0;
$ii2[$i*$ii_w] = 0;
$rowsum = 0;
$rowsum2 = 0;
for ($j=1; $j<$ii_w-1; $j++) {
$rgb = ImageColorAt($canvas, $j, $i);
$red = ($rgb >> 16) & 0xFF;
$green = ($rgb >> 8) & 0xFF;
$blue = $rgb & 0xFF;
$grey = (0.2989*$red + 0.587*$green + 0.114*$blue)>>0; // this is what matlab uses
$rowsum += $grey;
$rowsum2 += $grey*$grey;
$ii_above = ($i-1)*$ii_w + $j;
$ii_this = $i*$ii_w + $j;
$ii[$ii_this] = $ii[$ii_above] + $rowsum;
$ii2[$ii_this] = $ii2[$ii_above] + $rowsum2;
}
}
return array('ii'=>$ii, 'ii2' => $ii2);
}
protected function doDetectGreedyBigToSmall($ii, $ii2, $width, $height)
{
$s_w = $width/20.0;
$s_h = $height/20.0;
$start_scale = $s_h < $s_w ? $s_h : $s_w;
$scale_update = 1 / 1.2;
for ($scale = $start_scale; $scale > 1; $scale *= $scale_update) {
$w = (20*$scale) >> 0;
$endx = $width - $w - 1;
$endy = $height - $w - 1;
$step = max($scale, 2) >> 0;
$inv_area = 1 / ($w*$w);
for ($y = 0; $y < $endy; $y += $step) {
for ($x = 0; $x < $endx; $x += $step) {
$passed = $this->detectOnSubImage($x, $y, $scale, $ii, $ii2, $w, $width+1, $inv_area);
if ($passed) {
return array('x'=>$x, 'y'=>$y, 'w'=>$w);
}
} // end x
} // end y
} // end scale
return null;
}
protected function detectOnSubImage($x, $y, $scale, $ii, $ii2, $w, $iiw, $inv_area)
{
$mean = ($ii[($y+$w)*$iiw + $x + $w] + $ii[$y*$iiw+$x] - $ii[($y+$w)*$iiw+$x] - $ii[$y*$iiw+$x+$w])*$inv_area;
$vnorm = ($ii2[($y+$w)*$iiw + $x + $w]
+ $ii2[$y*$iiw+$x]
- $ii2[($y+$w)*$iiw+$x]
- $ii2[$y*$iiw+$x+$w])*$inv_area - ($mean*$mean);
$vnorm = $vnorm > 1 ? sqrt($vnorm) : 1;
$count_data = count($this->detection_data);
for ($i_stage = 0; $i_stage < $count_data; $i_stage++) {
$stage = $this->detection_data[$i_stage];
$trees = $stage[0];
$stage_thresh = $stage[1];
$stage_sum = 0;
$count_trees = count($trees);
for ($i_tree = 0; $i_tree < $count_trees; $i_tree++) {
$tree = $trees[$i_tree];
$current_node = $tree[0];
$tree_sum = 0;
while ($current_node != null) {
$vals = $current_node[0];
$node_thresh = $vals[0];
$leftval = $vals[1];
$rightval = $vals[2];
$leftidx = $vals[3];
$rightidx = $vals[4];
$rects = $current_node[1];
$rect_sum = 0;
$count_rects = count($rects);
for ($i_rect = 0; $i_rect < $count_rects; $i_rect++) {
$s = $scale;
$rect = $rects[$i_rect];
$rx = ($rect[0]*$s+$x)>>0;
$ry = ($rect[1]*$s+$y)>>0;
$rw = ($rect[2]*$s)>>0;
$rh = ($rect[3]*$s)>>0;
$wt = $rect[4];
$r_sum = ($ii[($ry+$rh)*$iiw + $rx + $rw]
+ $ii[$ry*$iiw+$rx]
- $ii[($ry+$rh)*$iiw+$rx]
- $ii[$ry*$iiw+$rx+$rw])*$wt;
$rect_sum += $r_sum;
}
$rect_sum *= $inv_area;
$current_node = null;
if ($rect_sum >= $node_thresh*$vnorm) {
if ($rightidx == -1) {
$tree_sum = $rightval;
} else {
$current_node = $tree[$rightidx];
}
} else {
if ($leftidx == -1) {
$tree_sum = $leftval;
} else {
$current_node = $tree[$leftidx];
}
}
}
$stage_sum += $tree_sum;
}
if ($stage_sum < $stage_thresh) {
return false;
}
}
return true;
}
}
Here's an example use:
include "facedetection/FaceDetector.php";
$detector = new svay\FaceDetector('detection.dat');
$detector->faceDetect($path);
$coord = $detector->getFace();
Any help or suggest other php thumbnails with face detection script.

Answer 1

Can you increase the time limit? You can use set_time_limit() or change your php.ini if you have access to it.
Also, how big is the detection.dat file? Loading the entire file in memory with file_get_contents() can take some time if the file is large.
Unless you mess up with the FaceDetection code (which is not recommended, unless you will never want to upgrade the library), you won't be able to stop the execution after 15 seconds. They don't provide any hooks where you could tell the script to stop.