function ResizeImg2($strSourceImagePath, $strDestImagePath, $intMaxWidth = 200, $intMaxHeight = 200)
{
    $arrImageProps = getimagesize($strSourceImagePath);
    $intImgWidth   = $arrImageProps[0];
    $intImgHeight  = $arrImageProps[1];
    $intImgType    = $arrImageProps[2];
 
    switch( $intImgType) {
        case 1: $rscImg = ImageCreateFromGif($strSourceImagePath);  break;
        case 2: $rscImg = ImageCreateFromJpeg($strSourceImagePath); break;
        case 3: $rscImg = ImageCreateFromPng($strSourceImagePath);  break;
        default: return false;
    }
 
    if ( !$rscImg) return false;
 
    if ($intImgWidth > $intImgHeight) {
        $fltRatio = floatval($intMaxWidth / $intImgWidth);
    } else {
        $fltRatio = floatval($intMaxHeight / $intImgHeight);
    }
 
    $intNewWidth  = intval($fltRatio * $intImgWidth);
    $intNewHeight = intval($fltRatio * $intImgHeight);
 
    $rscNewImg = ImageCreate($intNewWidth, $intNewHeight);
    if (!ImageCopyResized($rscNewImg, $rscImg, 0, 0,0, 0, $intNewWidth, $intNewHeight, $intImgWidth, $intImgHeight)) return false;
 
    switch($intImgType) {
        case 1:  $retVal = ImageGIF($rscNewImg, $strDestImagePath);  break;
        case 3:  $retVal = ImagePNG($rscNewImg, $strDestImagePath);  break;
        case 2:  $retVal = ImageJPEG($rscNewImg, $strDestImagePath, 90); break;
        default: return false;
    }
 
    ImageDestroy($rscNewImg);
 
    return true;
}
 
// Тест:
$strTestImgPath = dirname(__FILE__).'/testimg.gif';
$strDestImgPath = dirname(__FILE__).'/testimg.preview.gif';
 
print (int)ResizeImg2($strTestImgPath, $strDestImgPath, 300, 300);