How to test if a base64 string is a valid image in PHP?

Question

I tried the following code:

function convertAndSaveLogo($data, $id){
        if(isset($data->base64_image) && $data->base64_image){
            $imageData = base64_decode($data->base64_image);
            if($imageData){
                $source = imagecreatefromstring($imageData);
                if($source){
                    imagepng($source, getcwd()."../dir/image/".$id.".png", 5);
                    imagedestroy($source);
                }
            }
        }
    }

But it is not working.

@Musa The base64 string is a user supplied data, I need to know if it is a valid encoded image — , Apr 12 '15 at 20:33
@Musa If the base64 string is a invalid encoded image the function imagecreatefromstring will throw an error — , Apr 12 '15 at 20:41
@Musa Yes. Warning: imagecreatefromstring(): Empty string or invalid image. — , Apr 12 '15 at 20:50

Mahdi Bashirpour · Answer 1 · 2018-08-08T19:19:00.803

2

Try this:

if(base64_encode(base64_decode($img, true)) === $img)
   echo 'is a Base64-encoded string' ;

edited Aug 08 '18 at 19:19

answered Oct 21 '17 at 13:00

Mahdi Bashirpour

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Exact duplicate advice as: https://stackoverflow.com/a/10797086/2943403 – mickmackusa Jan 20 '22 at 11:26

score 1 · Answer 2 · answered Apr 12 '15 at 20:51

Look into two things

if $data->base64_image doesn't contain something like: 'data:image/jpeg;base64,', in my case replacing it to nothing does the job:

//in my case base64 data resides in: \Input::all()['img_data']
$base64img = str_replace(
     'data:image/jpeg;base64,', 
     '', 
     \Input::all()['img_data']
);

$data = base64_decode($base64img);

if you're saving that you can as well check this solution :

// if it returns FALSE then the uploaded file
// isn't a valid image
getimagesize($created_file);

I don't want to save the file if the base64 is not a valid encoded image. So I can not use getimagesize. — , Apr 12 '15 at 21:18

How to test if a base64 string is a valid image in PHP?

2 Answers2