PHP : binary image data, checking the image type

Question

Hello,

I have some images in bin, I want to check the header to check the format (jpg,png,etc)

I dont want to use temp files! I have a solution using TEMP FILES.

Thanks!

Answer 1

Are the files being uploaded or are they already on the file system?

Try using mime_content_type() to get the file's MIME format.

Answer 2

Why not just check the file entension? :)

An Alternative

if(exif_imagetype($filepath) == IMAGETYPE_JPEG){
    echo 'This is a JPEG image';
}

Answer 3

The bits start with:

$JPEG = "\xFF\xD8\xFF"
$GIF  = "GIF"
$PNG  = "\x89\x50\x4e\x47\x0d\x0a\x1a\x0a"
$BMP  = "BM"
$PSD  = "8BPS"
$SWF  = "FWS"

The other ones I wouldn't know right now, but the big 3 (jpeg,gif,png) usually cover 99%. So, compare the first bytes to those string, and you have your answer.

Answer 4

Here's an implementation of the function as described by Wrikken

function getImgType($filename) {
    $handle = @fopen($filename, 'r');
    if (!$handle)
        throw new Exception('File Open Error');

    $types = array('jpeg' => "\xFF\xD8\xFF", 'gif' => 'GIF', 'png' => "\x89\x50\x4e\x47\x0d\x0a", 'bmp' => 'BM', 'psd' => '8BPS', 'swf' => 'FWS');
    $bytes = fgets($handle, 8);
    $found = 'other';

    foreach ($types as $type => $header) {
        if (strpos($bytes, $header) === 0) {
            $found = $type;
            break;
        }
    }
    fclose($handle);
    return $found;
}

Answer 5

Use the fileinfo PHP extension:

http://de.php.net/manual/en/function.finfo-file.php

Its using the "file" *nix command to reliably determine the mime-type of a given file:

$finfo = finfo_open(FILEINFO_MIME_TYPE); 
$mimetype = finfo_file($finfo, $filename);
finfo_close($finfo);

This extension is shipped with PHP 5.3 or can be installed from pecl (pecl install fileinfo) for earlier versions.

Answer 6

http://php.net/manual/en/function.getimagesize.php

"Index 2 is one of the IMAGETYPE_XXX constants indicating the type of the image."