PHP : binary image data, checking the image type

Question

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

I don't want to use temp files! I have a solution using TEMP FILES.

score 53 · Answer 1 · edited Sep 25 '19 at 12:19

53

I can see that most of you didn't understand the question :) (question was how to validate binary data in buffer, not a file on disk).

I had same problem, and resolved it with:

$finfo = new finfo(FILEINFO_MIME_TYPE);
$mimeType = $finfo->buffer($rawImage);

edited Sep 25 '19 at 12:19

Rein Baarsma

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answered Jun 28 '12 at 15:33

Marcin Hubert

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This solution is the best, if you are using PHP > 5.3 – djleop Oct 09 '12 at 13:12
2

This should indeed be upvoted above mine with the current state of PHP, 5.3 is getting old. – Wrikken Aug 19 '14 at 16:39
You get something similar to `application/pdf; charset=binary` Which, in turn, can be extracted this way: `list($mime, $raw_charset) = explode(';', $finfo->buffer($rawImage));` and then (if you need the charset): `$charset = explode('=', trim($raw_charset))[1];` – Cédric Françoys Apr 18 '18 at 09:38

Wrikken · Accepted Answer · 2010-07-22T21:34:08.607

27

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.

edited Jul 22 '10 at 21:34

answered Jul 22 '10 at 20:12

Wrikken

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2

Could you give an example of how you would check these against some binary data using php? thanks – DonutReply May 10 '11 at 16:44
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@DonutReply - just for the people searching it: https://gist.github.com/CodeBrauer/5fe9ad14fa9786b3d1f6 – CodeBrauer Mar 27 '15 at 14:00
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Do you have any information about the last bits to find out the end of an image? – Daniel Oct 06 '17 at 14:58
@Daniel Did find out end bytes.Am also searching for same thing. – Murali Oct 10 '17 at 05:49

quantumSoup · Answer 3 · 2010-07-22T20:46:00.230

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;
}

score 1 · Answer 4 · answered Jul 22 '10 at 19:35

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.

answered Jul 22 '10 at 19:35

pferate

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score 1 · Answer 5 · answered Jul 22 '10 at 20:42

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.

score 0 · Answer 6 · answered Jul 22 '10 at 23:04

0

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

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

answered Jul 22 '10 at 23:04

GameZelda

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See function docs, it is written there not to use it for "is image" checks. – Kirzilla Aug 16 '20 at 15:44

Dutchie432 · Answer 7 · 2010-07-22T20:15:46.547

-1

Why not just check the file entension? :)

An Alternative

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

edited Jul 22 '10 at 20:15

answered Jul 22 '10 at 19:59

Dutchie432

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So most of your GIF files are not actually GIFs? There is really NO reason this wouldn't work unless you are dealing with user uploads, and even then you likely have nothing to worry about. – Dutchie432 Jul 22 '10 at 20:13
In 2012, some users believe they can convert images just by renaming the file... So, it's not reliable. – djleop Oct 09 '12 at 13:14

PHP : binary image data, checking the image type

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