Installing OC to use ImageMagick without the MagickWand extension

seth

One of the most common problems when installing OpenCollection has been getting the MagickWand PHP extension installed and working. It can be quite tricky to build on your own, is generally not a part of Linux distributions or packages and is not supported by many ISPs.

Up to now, MagickWand has been an absolute requirement for use of ImageMagick. No MagickWand meant no ImageMagick. And without ImageMagick the number of image file formats OC can support is limited.

To solve this problem we've developed a new media processing plug-in for OC that uses the command-line ImageMagick programs to perform graphics processing. So long as you have ImageMagick installed on your server for command line use, OC can now use it. The MagickWand PHP extension is no longer necessary but will still work.

The new plug-in has not been extensively tested, so we would appreciate you giving it a try and letting us know how it works for you. Once we are sure it is stable we'll incorporate it into an OC update.

All you need to do to get the new plug-in working is to install two files and update your external_applications.conf file to include the directory path containing the ImageMagick command-line programs. OC will detect whether you have MagickWand, ImageMagick or GD installed and use them accordingly and in the order listed.

You can download the plug-in at: http://www.opencollection.org/downloads/magick_files_11feb08.tgz The download includes installation instructions.

seth

stefan

Hi,

i just quickly compiled IM 6.38 from source and removed the GD library from my Debian box here (to be sure that the new plugin is used). When uploading a small image (that is below the taskQueue threshold) I get the following error:

Warning: fopen(<mywebroot>/octest/media/testoc/tilepics/0/82422_object_representations_media_9_tilepic.tpc) [function.fopen]: failed to open stream: Permission denied in <somedir>/home/includes/lib/parsers/TilepicParser.inc on line 938

The referenced directory is empty ...

I will try to figure out the cause later.

stefan

Argh - ok. It was simple. I ran the processTaskQueue tool manually as root when using it the first time at this test-installation. Therefore the owner of the .../0/ dir was root. After chowning it, the new plugin seems to work.

seth

I should also mention that the MagickWand-based TilePic encoder will probably perform better than the command-line one. For small and medium size images this should not be too noticeable, but for very large images the fact that every tile creation requires a full image read is going to hurt a lot. With MagickWand we can read the image once and keep it in memory as we generate tiles.

So there is still a reason to keep the MagickWand plug-in around, and for people to use it if they can.

We are also going to create a plug-in built around the IMagick PHP extension. When we started OC IMagick was terrible and buggy but it has become much better and it seems to be better supported by Linux distributions in packages than MagickWand. Like MagickWand, an IMagick-based plugin would be efficient when creating TilePics.

seth

There are new MagickWand-less plugin files available at http://www.opencollection.org/downloads/magick_files_19feb08.tgz

The only issue addressed in this update is compatibility with the PHP open_basedir restriction which is imposed by some ISPs. Some OC media processing plug-ins had used file_exists() to determine whether needed command line executables existed, and since the commands are usually outside of your home directory open_basedir forces file_exists to return false and throws a warning.

The revised plug-ins use exec() on the command and test the return value instead of file_exists(). This seems to work.

All plug-ins that use exec()'ed command line programs have been updated. This includes MagickWand (which uses the dcraw command for camera RAW images), ImageMagick, Video (which used ffmpeg) and PDFWand (which uses Ghostscript).

A couple of other problems that we are still working to address:

the Video plug-in relies upon MagickWand to generate thumbnails and animated GIF previews. Without MagickWand you can still convert video, but you won't get any nice preview thumbnails.
the PDFWand plug-in will not run at all without MagickWand, which means you can't process PDF files without MagickWand.

We are working to generalize both plug-ins to only require any one of the image plugins (ImageMagick, MagickWand or GD) work. Updated plug-ins should be available in a few days.

seth

stefan

Ok, after testing this 2 minutes some weeks ago on my debian machine now the time has come to get this to work on our productive system - with some kind of strange setup. And what happened? It doesn't work ;)

So it would be nice if you could assist me while troubleshooting this.

First of all I took the file from the post above and copied all files in the corresponding directories (I hope I did so).

~/oc_config/MagickFiles> cp -r * ../home/includes/lib/

Then I tested our ImageMagick installation:

~/oc_config> convert -version Version: ImageMagick 6.2.5 10/12/07 Q16 http://www.imagemagick.org ~/oc_config> file -i logo_kv.tiff logo_kv.tiff: image/tiff ~/oc_config> convert logo_kv.tiff logo.png ~/oc_config> file -i logo.png logo.png: image/png

So it can handle tiffs correctly.

~/oc_config> which convert /usr/bin/convert

So the following line has been added to the external_applications.conf:

imagemagick_path = /usr/bin

But when I upload the file I converted with the command line tool above in OC i get

Warning: Division by zero in <somedir>/oc_config/home/includes/lib/plugins/Media/ImageMagick.inc on line 401 Warning: Division by zero in <somedir>/oc_config/home/includes/lib/plugins/Media/ImageMagick.inc on line 402

On the file space it looks like this:

No image logo_kv.tif TIFF wxh pixels 0.2M

Unfortunately I didn't have the time to have a look at the code yet. Maybe you have some idea on this?

seth

Try running this command on a TIFF file, preferably the one you are trying to upload:

identify -format "%m;%w;%h

What does it return?

stefan

~/oc_config> identify -format "%m;%w;%h" logo_kv.tiff TIFF;9368;10054

seth

And this command:

which identify

returns /usr/bin/identify

stefan

Yes.

oc_config> which identify /usr/bin/identify

seth

Ok, I have no idea. Time to wheel out the print statements.

What it sounds like is happening is that the call to /usr/sbin/identify is failing and not extracting the width and height properly. If you open up home/includes/lib/plugins/Media/ImageMagick.inc and take a look at the function _imageMagickRead(). Print out the output of the identify command and then use OC to upload, and let me know what comes out.

seth

stefan

Tomorrow ... I cannot access the server from home.

But thanks for your help anyway!

stefan

I just added those 2 lines after the exec command in line 804:

echo "vn_return:"; print_r($vn_return); echo "va_output:"; print_r($va_output);

when I upload the file again, the result is this:

vn_return:0 va_output:Array ( [0] => TIFF;w;h )

And I tested other TIFFs as well - same result.

seth

What version of ImageMagick are you using? Can you send me the output of this command:

identify -version

stefan

I posted the output of convert -version in the big post above. But here's the one for identify:

seth

Ok, this is kind of weird then. Identify is not returning width and height info when called. I'll see if I can reproduce this here on one of our machines and post results soon.

seth

stefan

Maybe I can send you the ImageMagick package we installed on our server (SuSE rpm), but this will not happen before Monday since I have to ask one of our admins for the repository where they got it from.

But hey, maybe I can get them to compile an alternate version from source to test if this is a problem with those binaries.

We'll see ... Have a nice weekend!