imagick resize base64 image to base64 image in php

$PostImage = $_POST['PostImage'];
	
$imageBlob = base64_decode(str_ireplace('data:image/png;base64,','',$PostImage));
$im = new Imagick();
$im->readImageBlob($imageBlob);
//$im = new Imagick($_FILES['imageForPost']["tmp_name"]);
            $imageprops = $im->getImageGeometry();
    $finalWidth = 512;
    $finalHeight = 512;
    
            $ext = '.png';        
           
            $size = 40;            
         
                $width = $imageprops['width'];
                $height = $imageprops['height'];
                if($height > $finalHeight){
                $newHeight = $finalHeight;
                $newWidth = ($finalHeight / $height) * $width;
                }else{
                $newWidth = $imageprops['width'];
                $newHeight = $imageprops['height'];
                }

                $im->scaleImage($finalWidth,$finalHeight,true,true);  

                        $canvas = new Imagick();
                        $canvas->newImage($finalWidth, $finalHeight,  'white', 'png');                                              
                
                    $canvas->blurImage(25, 5);
                    $imageprops = $im->getImageGeometry();
                    $newWidth = $imageprops['width'];
                    $newHeight = $imageprops['height'];
                    if($finalWidth == $finalHeight){
                        $pos = 0;
                        $posh = ($finalHeight - $newHeight)/2;
                    }else{
                        $pos = ($finalWidth - $newWidth)/2;
                        $posh = ($finalHeight - $newHeight)/2;
                    }
                    
                    $canvas->compositeImage($im, Imagick::COMPOSITE_OVER,  $pos, $posh);
                  
                    $canvas->setOption('jpeg:extent', $size.'kb');
                    $canvas->setImageFormat( "jpeg" );
                   
				$thumbnail = $im->getImageBlob();	
				$PostImage = $thumbnail;
				
				echo "<img src='data:image/jpg;base64,".base64_encode($thumbnail)."' />";