php分析gif图片的问题

[PHP编程者]

我有个小程序，以前可以分析png图片，但现在用同样的算法来分析gif图片，则不能分析，出问题处的代码如下：

class competitor_360buy_ImageRule extends competitor_ImageRule
	{
		
		function __construct()
		{
			$this->set_color_filter(array(230,255,0,10,0,10),array(200,255,200,255,200,255));
		}
		
		function save($img,$path)
		{
			$path = $path.rand(0,100000000).'.gif';
			imagegif($img,$path);
			return $path;
		}

		function getBlock($img,$size)//$img是被分析的图片的标识符,$size是其大小
		{
			$stat = 0;
			$start = 0;
			$end = 0;
			$block = 0;
			$imgs = array();
			$n = 0;
			$has_word = 0;
			
			$word_color = imagecolorallocate($img, 0, 0, 0);				//为一幅图像分配颜色
			$blank_color = imagecolorallocate($img, 255, 255, 255);
			
//			var_dump($img);
//			exit;
			
			for($i = 0; $i < $size[0]; ++$i) {
				$has_word = 0;
				for($j =0; $j < $size[1]; ++$j){
					$pixelrgb = imagecolorat($img,$i,$j);				//取得某像素的颜色索引值
					$cols = imagecolorsforindex($img, $pixelrgb);			//取得某索引的颜色
					$cf = $this->color_filter($cols);			//匹配颜色值，白返1，黑返0，否则返2

					switch($cf) {
					case 1:
						if($stat == 0) {//如果还没开始一个新的块，启动它
							$stat = 1;
							$start = $i;
						}
						$has_word++;
						imagesetpixel($img,$i,$j,$word_color);			//画一个单一像素
						break;
					case 0:
						if($stat == 1 && $j == $size[1] - 1 && $has_word == 0) {
							$stat = 0;
							$end = $i;
							$width = $end - $start;
							
							$tmp_img =imagecreatetruecolor($width,$size[1]);

							imagecopy($tmp_img,$img,0,0,$start,0,$width,$size[1]);
							$imgs[$n]['image'] = $tmp_img;
							$imgs[$n]['width'] = $width;
							$imgs[$n]['height'] = $size[1];
							++$n;
					//		imagegif($tmp_img,rand(0,100000).'.gif');
						}
						imagesetpixel($img,$i,$j,$blank_color);
						break;
					case 2:
						imagesetpixel($img,$i,$j,$word_color);
						break;
					}
					
			//		if($cf == 'word')break;
				}
			}
			parent::__construct();
			$stat = 0;
			
			
			foreach($imgs as &$img){
				$tmp_img =imagecreatetruecolor($img['width'],11);
				imagecopy($tmp_img,$img['image'],0,0,0,4,$img['width'],11);
				$img['image'] = $tmp_img;
				$img['height'] = 11;
			}
			return $imgs;
		}
	}

color_filter所在的类如下，执行完上面的getBlock（）函数后打印$imgs为空，问题可能出在什么地方呢？

//用于拆分图片中的文字
	abstract class competitor_imagerule
	{
		protected $_image_type = 'gif';
		
		function __construct()
		{
			$this->set_color_filter(array(0,0,0,0,0,0),array(255,255,255,255,255,255));
		}
		
		abstract function getBlock($img,$size);
		
		function get_type()
		{
			return $this->_image_type;
		}
		
		//文字拆分函数，返回图片资源数组；
		
		function getImage($file)
		{
			$type = image_type_to_mime_type(exif_imagetype($file));
			$a = array();
			preg_match('/\/(.*)$/',$type,$a);
			if($a[1]!='gif'){
				return false;
			}
			
			return imagecreatefromgif($file);
		}
		
		function save() 
		{
			return true;
		}
		
		//查看输入的色彩是否在范围内
		function color_filter($cols,$d = 'h')
		{
			//print_r($this);
			if(
				$cols['red']	<= $this->max_r &&
				$cols['red']	>= $this->min_r &&
				$cols['green']	<= $this->max_g &&
				$cols['green']	>= $this->min_g &&
				$cols['blue']	<= $this->max_b &&
				$cols['blue']	>= $this->min_b) {
				
				return 1;
			}elseif(
				$cols['red']	<= $this->blank_max_r &&
				$cols['red']	>= $this->blank_min_r &&
				$cols['green']	<= $this->blank_max_g &&
				$cols['green']	>= $this->blank_min_g &&
				$cols['blue']	<= $this->blank_max_b &&
				$cols['blue']	>= $this->blank_min_b) {
			
				return 0;
			}else{
				if($d == 'h')
					return 2;
				else 
					return 0;
			}
		}
		
		function set_color_filter($cols,$cols_blank)
		{
			$this->min_r = $cols[0];
			$this->max_r = $cols[1];
			$this->min_g = $cols[2];
			$this->max_g = $cols[3];
			$this->min_b = $cols[4];
			$this->max_b = $cols[5];
			
			$this->blank_min_r = $cols_blank[0];
			$this->blank_max_r = $cols_blank[1];
			$this->blank_min_g = $cols_blank[2];
			$this->blank_max_g = $cols_blank[3];
			$this->blank_min_b = $cols_blank[4];
			$this->blank_max_b = $cols_blank[5];
		}
		
		function set_blank()
		{
			
		}

	}

[PHP编程者]

我就是想把这个网址里面的新蛋价格解析出来，http://www.newegg.com.cn/Product/98-c25-007.htm

[life169]

那个价格图片是bmp位图。不是gif格式。