tady je fci, kterou jsem trosku poupravil.... (muzes nastavovat vynucenou sirku, vysku nebo sirku a vysku)
function thumbnailplusplus($src, $saveas, $tparams)
{
	$tparams = explode('&',$tparams);
	$params = array();
	foreach ($tparams as $par)
	{
		$t = explode('=',$par);
		$params[$t[0]] = $t[1];
	}
	$img = $src;
	$percent = $params['percent'];
	$constrain = $params['constrain'];
	// get image size of img
	$x = @getimagesize($img);
	// image width
	$sw = $x[0];
	// image height
	$sh = $x[1];
	//use forced params
	if(is_numeric($params['fh']) || is_numeric($params['fw']))
	{
		if(is_numeric($params['fh']))
		{
			$h = $params['fh'];
			$w = null;
		}
		if(is_numeric($params['fw']))
		{
			$w = $params['fw'];
			$h = null;
		}	
	}
	else
	{
		//width bigger, resize according to width params
		if($sw > $sh)
		{
			$w = $params['w'];
			$h = null;
			if($sw < $w)
			{
				copy($src,$saveas);
				return null;
			}
		}
		//use height
		else
		{
			$h = $params['h'];
			$w = null;
			if($sh < $h)
			{
				copy($src,$saveas);
				return null;
			}
		}
	}
	if ($percent > 0) {
		// calculate resized height and width if percent is defined
		$percent = $percent * 0.01;
		$w = $sw * $percent;
		$h = $sh * $percent;
	} else {
		if (isset ($w) AND !isset ($h)) {
			// autocompute height if only width is set
			$h = (100 / ($sw / $w)) * .01;
			$h = @round ($sh * $h);
		} elseif (isset ($h) AND !isset ($w)) {
			// autocompute width if only height is set
			$w = (100 / ($sh / $h)) * .01;
			$w = @round ($sw * $w);
		} elseif (isset ($h) AND isset ($w) AND isset ($constrain)) {
			// get the smaller resulting image dimension if both height
			// and width are set and $constrain is also set
			$hx = (100 / ($sw / $w)) * .01;
			$hx = @round ($sh * $hx);
			$wx = (100 / ($sh / $h)) * .01;
			$wx = @round ($sw * $wx);
			if ($hx < $h) {
				$h = (100 / ($sw / $w)) * .01;
				$h = @round ($sh * $h);
			} else {
				$w = (100 / ($sh / $h)) * .01;
				$w = @round ($sw * $w);
			}
		}
	}
	$im = @ImageCreateFromJPEG ($img) or // Read JPEG Image
	$im = @ImageCreateFromPNG ($img) or // or PNG Image
	$im = @ImageCreateFromGIF ($img) or // or GIF Image
	$im = false; // If image is not JPEG, PNG, or GIF
	if (!$im) {
		// We get errors from PHP's ImageCreate functions...
		// So let's echo back the contents of the actual image.
		readfile ($img);
	} else {
		// Create the resized image destination
		$thumb = @ImageCreateTrueColor ($w, $h);
		// Copy from image source, resize it, and paste to image destination
		@ImageCopyResampled ($thumb, $im, 0, 0, 0, 0, $w, $h, $sw, $sh);
		// Output resized image
		@ImageJPEG ($thumb,$saveas,90);
	}
}