在保存到数据库之前如何压缩图像大小而不会降低质量

Question

i have a from and from that i forced user to upload a image and other details etc....And in my root directory i created one folder called(user_images) Every thing is fine , but the problem is..user may insert large files so that loading of webpage is slow... how to resize before uploading to database...

here is my code...

if(isset($_POST['btnsave']))
{
    $camname = $_POST['cam_name'];// user name
    $modelname = $_POST['model'];// user email
    $rentpday = $_POST['rent_pday'];// user name
    $usermob = $_POST['mob'];// user email
    $useraddrs = $_POST['addrs'];// user email
    $upd_date =date('Y-m-d H:i:s');//upl_date

    $imgFile = $_FILES['user_image']['name'];
    $tmp_dir = $_FILES['user_image']['tmp_name'];
    $imgSize = $_FILES['user_image']['size'];


    if(empty($camname)){
        $errMSG = "Please Enter Cam name.";
    }
    else if(empty($usermob)){
        $errMSG = "Please mobile number";
    }
    else if(empty($camname)){
        $errMSG = "Please enter cam_name";
    }
    else if(empty($modelname)){
        $errMSG = "Please enter model";
    }
    else if(empty($rentpday)){
        $errMSG = "Please enter rent per day";
    }
    else if(empty($imgFile)){
        $errMSG = "Please Select Image File.";
    }
    else
    {
        $upload_dir = 'user_images/'; // upload directory

        $imgExt = strtolower(pathinfo($imgFile,PATHINFO_EXTENSION)); // get image extension

        // valid image extensions
        $valid_extensions = array('jpeg', 'jpg', 'png', 'gif'); // valid extensions

        // rename uploading image
        $userpic = rand(1000,1000000).".".$imgExt;

        // allow valid image file formats
        if(in_array($imgExt, $valid_extensions)){           
            // Check file size '5MB'
            if($imgSize < 5000000)              {
                move_uploaded_file($tmp_dir,$upload_dir.$userpic);
            }
            else{
                $errMSG = "Sorry, your file is too large.";
            }
        }
        else{
            $errMSG = "Sorry, only JPG, JPEG, PNG & GIF files are allowed.";        
        }
    }


    // if no error occured, continue ....
    if(!isset($errMSG))
    {


        $stmt = $user_home->runQuery("UPDATE post_data 
                                      set cam_name=?,
                                      cam_model =?, 
                                      cam_rent=?,
                                      cam_img=?,
                                      mobile=?,
                                      address=?,
                                      upd_date=? 
                                      where userID=?
                                      ");

        $stmt->bindParam(1,$camname);
        $stmt->bindParam(2,$modelname);
        $stmt->bindParam(3,$rentpday);
        $stmt->bindParam(4,$userpic);
        $stmt->bindParam(5,$usermob);
        $stmt->bindParam(6,$useraddrs);
        $stmt->bindParam(7,$upd_date);
        $stmt->bindParam(8,$id);

        if($stmt->execute())
        {

            $successMSG = "Record saved success";
        }
        else
        {
            $errMSG = "error while inserting....";
        }

    }
}

Any changes in this code to compress image size before uploading.. thanks in advance..

Answer 1

AFAIK, you can't maintain the quality while reducing the size of the image. You could use imagejpeg , to reduce the size of the image by reducing it quality.

When you are about to save the image, you need to reduce the quality of image first.

        if($imgSize < 5000000) {
            $image = imagecreatefromjpeg($upload_dir.$userpic);
            imagejpeg($image, $new_image_path, 70);
            move_uploaded_file($tmp_dir,$new_image_path);
        }

Answer 2

It is actually super easy to compress images. Just change them all over to png:

$image = imagecreatefromstring(file_get_contents($tmp_dir));
$saveLocation = “user_images/”.md5(uniqid()).”png”;
//Please use this instead of your current file naming method to remove the possibility of a duplicate (which rand will sometimes yield)
imagepng($image,$saveLocation,9);
//9 represents the compression level (0 no compression - 9 max compression)

That's really it! Png is a lossless compression method so you won't lose any quality in the process