How to Determine Image Type from Base64 String in PHP?

Determine Image Type from Base64 String in PHP

Is it feasible to ascertain the file type of an image encoded as a base64 string in PHP? Unfortunately, solely possessing the encoded string presents a challenge in acquiring the image's original file type. To decipher the image type, one might utilize the imagecreatefromstring() function, which generates an image resource. However, this resource possesses a specialized representation in PHP, obscuring the original image type.

Fortunately, the PHP FileInfo extension offers a solution. This extension provides a straightforward method to determine the file type of binary data, including base64-encoded strings. Here's how it works:

<code class="php">$encoded_string = "....";
$imgdata = base64_decode($encoded_string);

$f = finfo_open();

$mime_type = finfo_buffer($f, $imgdata, FILEINFO_MIME_TYPE);</code>

This code snippet decodes the base64-encoded string, opens a FileInfo resource, and obtains the file type using the finfo_buffer() function. The resulting $mime_type variable will contain the file type, such as "image/jpeg" or "image/png". With this information, you can determine the original file type without needing to know it beforehand and can save the image as the appropriate file type.

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