<form enctype="multipart/form-data" method="post" action="upload.php"">
  <input type="file" name="id_pic[]" accept="image/*" class="form-control" multiple />
  <input type="submit" value="上传 " />
</form>

<form enctype="multipart/form-data" method="post" action="upload.php"">
  <input type="file" name="id_pic_1" accept="image/*" class="form-control" />
  <input type="file" name="id_pic_2" accept="image/*" class="form-control" />
  <input type="submit" value="上传 " />
</form>

array(1) {
 ["id_pic"] => array(5) {
  ["name"] => array(2) {
   [0] => string(5) "1.jpg"
   [1] => string(5) "2.jpg"
  }
  ["type"] => array(2) {
   [0] => string(10) "image/jpeg"
   [1] => string(10) "image/jpeg"
  }
  ["tmp_name"] => array(2) {
   [0] => string(27) "C:\Windows\Temp\php7A7E.tmp"
   [1] => string(27) "C:\Windows\Temp\php7A7F.tmp"
  }
  ["error"] => array(2) {
   [0] => int(0)
   [1] => int(0)
  }
  ["size"] => array(2) {
   [0] => int(77357)
   [1] => int(56720)
  }
 }
}

   array(2) {
 ["id_pic_1"] => array(5) {
  ["name"] => string(5) "1.jpg"
  ["type"] => string(10) "image/jpeg"
  ["tmp_name"] => string(27) "C:\Windows\Temp\phpBBEE.tmp"
  ["error"] => int(0)
  ["size"] => int(77357)
 }
 ["id_pic_2"] => array(5) {
  ["name"] => string(5) "2.jpg"
  ["type"] => string(10) "image/jpeg"
  ["tmp_name"] => string(27) "C:\Windows\Temp\phpBBEF.tmp"
  ["error"] => int(0)
  ["size"] => int(56720)
 }
}

function dealFiles($files) {
    $fileArray = array();
    $n     = 0;
    foreach ($files as $key=>$file){
      if(is_array($file['name'])) {
        $keys    =  array_keys($file);
        $count   =  count($file['name']);
        for ($i=0; $i<$count; $i++) {
          $fileArray[$n]['key'] = $key;
          foreach ($keys as $_key){
            $fileArray[$n][$_key] = $file[$_key][$i];
          }
          $n++;
        }
      }else{
        $fileArray = $files;
        break;
      }
    }
    return $fileArray;
 }

//php示例：
$img = base64_decode($_POST['img']);
$img = imagecreatefromstring($img);