Home of Peter HazaOpinions on most things

Reading IPTC IIM/headers

IPTC is a trickier beast from a PHP perspective. We’ve been given two functions to work with, iptcparse() and iptcembed().

iptcparse() is almost as easy as exif_read_data(), but unfortunately it requires more pre-work than exif_read_data(). JPEG saves application data in markers named APPn where n is a number. IPTC is most often (almost always) saved in APP13. To get this IPTC binary blob, we can use the slightly awkwardly named function getimagesize()‘s second(!) parameter.

$info = array();                      
getimagesize('05042008042.jpg', $info);
print_r(array_keys($info));
Array
(
    [0] => APP1
)

Two things to note:

1. I only print the array keys, because APPn markers holds binary data which makes little sense to print out.
2. My image only contains APP1 (which by coincidence is where Exif is usually stored), but no APP13. This is actually expected because IPTC is “human” (as mentioned near the start of the article) and thus not present without someone adding it.

Now if our image had IPTC data, we could do something like this.

$info = array();                      
getimagesize('05042008042.jpg', $info);
if(isset($info['APP13']))
{
    $iptc = iptcparse($info['APP13']);
    print_r($iptc);
}
Array
(
    [2#080] => Array
        (
            [0] => ccc
        )

    [2#110] => Array
        (
            [0] => ccc
        )

    [2#115] => Array
        (
            [0] => ccc
        )

    [2#118] => Array
        (
            [0] => ddd
        )

    [2#120] => Array
        (
            [0] => aaa
        )
)

This is from a test image I used at work, so the contents looks pretty cryptic or nonsense (aaa, bbb, ccc), but these fields are author, author, author, contact and caption in clear text, I just didn’t add any sensible data. The array indices may also seem a bit cryptic, but the number before the hash refers to the application record no. 2 (mentioned on previous page), and the number behind the hash refers to a predefined index which you find in the IPTC IIM specification.

Turn the page for how to write IPTC headers

Pages: 1 2 3