Image resize issue in PHP - gd creates ugly resized images

Question

I am creating thumbnails of fixed height and width from my PHP script using the following function

/*creates thumbnail of required dimensions*/
function createThumbnailofSize($sourcefilepath,$destdir,$reqwidth,$reqheight,$aspectratio=false)
{
    /*
     * $sourcefilepath =  absolute source file path of jpeg
     * $destdir =  absolute path of destination directory of thumbnail ending with "/"
     */
    $thumbWidth = $reqwidth; /*pixels*/
    $filename = split("[/\\]",$sourcefilepath);
    $filename = $filename[count($filename)-1];
    $thumbnail_path = $destdir.$filename;
    $image_file = $sourcefilepath;

    $img = imagecreatefromjpeg($image_file);
    $width = imagesx( $img );
    $height = imagesy( $img );

    // calculate thumbnail size
    $new_width = $thumbWidth;
    if($aspectratio==true)
    {
        $new_height = floor( $height * ( $thumbWidth / $width ) );
    }
    else
    {
        $new_height = $reqheight;
    }

    // create a new temporary image
    $tmp_img = imagecreatetruecolor( $new_width, $new_height );

    // copy and resize old image into new image
    imagecopyresized( $tmp_img, $img, 0, 0, 0, 0, $new_width, $new_height, $width, $height );

    // save thumbnail into a file

    $returnvalue = imagejpeg($tmp_img,$thumbnail_path);
    imagedestroy($img);
    return $returnvalue;
}

and I call this function with following parameters

createThumbnailofSize($sourcefilepath,$destdir,48,48,false);

but the problem is the resulting image is of very poor quality, when I perform the same operation with Adobe Photo shop, it performs a good conversion.. why it is so? I am unable to find any quality parameter, through which I change the quality of output image..

score 25 · Accepted Answer · edited Jul 08 '12 at 12:46

25

Use imagecopyresampled() instead of imagecopyresized().

edited Jul 08 '12 at 12:46

answered Oct 07 '09 at 19:24

timdev

61,857
6
82
92

2

imagecopyresampled() uses the bi-cubic resizing algorithm – Jacco Oct 07 '09 at 20:04
Thanks a lot, let me give a try to this function – Muhammad Ummar Oct 07 '09 at 20:06
2

Other important point: If some thumbnails are totally black. The issue may come from some cameras and cellphones that add some extra characters. To avoid this issue, add this: `ini_set("gd.jpeg_ignore_warning", 1);`. Then you will only get this warning `Corrupt JPEG data: 2 extraneous bytes before marker 0xd9` but the thumbnail will be correctly generated. – Toto Oct 07 '09 at 20:26

score 1 · Answer 2 · answered Oct 07 '09 at 19:27

if it is image quality you are after you need to give the quality parameter when you save the image using imagejpeg($tmp_img,$thumbnail_path,100) //default value is 75

/*creates thumbnail of required dimensions*/
function 
createThumbnailofSize($sourcefilepath,$destdir,$reqwidth,$reqheight,$aspectratio=false)
{
    /*
     * $sourcefilepath =  absolute source file path of jpeg
     * $destdir =  absolute path of destination directory of thumbnail ending with "/"
     */
    $thumbWidth = $reqwidth; /*pixels*/
    $filename = split("[/\\]",$sourcefilepath);
    $filename = $filename[count($filename)-1];
    $thumbnail_path = $destdir.$filename;
    $image_file = $sourcefilepath;

$img = imagecreatefromjpeg($image_file);
$width = imagesx( $img );
$height = imagesy( $img );

// calculate thumbnail size
$new_width = $thumbWidth;
if($aspectratio==true)
{
    $new_height = floor( $height * ( $thumbWidth / $width ) );
}
else
{
    $new_height = $reqheight;
}

// create a new temporary image
$tmp_img = imagecreatetruecolor( $new_width, $new_height );

// copy and resize old image into new image
imagecopyresized( $tmp_img, $img, 0, 0, 0, 0, $new_width, $new_height, $width, $height );

// save thumbnail into a file

$returnvalue = imagejpeg($tmp_img,$thumbnail_path,100);
imagedestroy($img);
return $returnvalue;

}

Just increasing the Quality parameter does not help. resample improves the quality — rjha94, Mar 06 '12 at 18:15

score 1 · Answer 3 · answered Oct 07 '09 at 19:31

You could also consider using ImageMagick (http://us3.php.net/manual/en/book.imagick.php) instead of Gd. I had the same problem just a couple of days ago with Java. Going for ImageMagick instead of Java Advanced Images resultet in a huge quality difference.

richid · Answer 4 · 2022-07-29T04:06:02.203

0

You might also want to take a look at the Image_Transform PEAR package. It takes care of a lot of the low-level details for you and makes creating and manipulating images painless. It also lets you use either GD or ImageMagick libraries. I've used it with great success on several projects.

edited Jul 29 '22 at 04:06

answered Oct 07 '09 at 19:33

richid

562
3
7
22

score 0 · Answer 5 · answered Mar 04 '11 at 12:08

0

tried using the php.Thumbnailer ?

$thumb=new Thumbnailer("photo.jpg");
$thumb->thumbSquare(48)->save("thumb.jpg");

Result photo will be 48x48px. Easy right? :)

answered Mar 04 '11 at 12:08

user644602

44
2

Image resize issue in PHP - gd creates ugly resized images

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