imagick convert to ico fails for some files

Question

here I have to cache about 2000 favicon.ico files for performance enhancements. I grab the files and try to shrink them via IMagick (v.6.6.0) and PHP 5.3.5 The PHP code for this is

try {
$image = new Imagick($im_hint . ':' . BASE . '/upload/favicon.ico');
$image->cropThumbnailImage(16, 16);
$image->setImageFormat('ico');
$image->writeImage(BASE . '/favicons/' . $id[0] . '/' . $id[1] . '/' . $id[2] . '/' . $id . '.ico');
} catch (Exception $e) { die($e->getMessage()); }

where $im_hint could be ico, png, jpg and so on. For 99% of the files all is fine and I get a working ICO file. But for one percent of files, I get only a blank ICO file and I don't know why? An example for an ICO file where this code fails is http://www.augensound.de/favicon.ico I tried to comment out the cropThumbnailImage call and try to use setFormat instead of setImageFormat and tried to save it as PNG...but nothing works. There is also no exception.

Regards

Answer 1

Not an answer to your question, but I get a blank image too when I open the example file in IrfanView or PhotoImpact. It's not a multi-page/multi-resolution file so there is nothing to switch. The canvas just is blank.

Windows 7's built-in preview renders it fine, though.

It could be that IM can't deal with these files because they have the wrong format or sub-format.