Maephisto:
Great post. Few things here:
1. Typically, you will want to use an Alfresco for your creative team to
create and manage digital assets. They can use a custom view of that
space that provides a thumbnail view of assets (available via a
contributed Forget project). That space can be configured with a
content rule to execute whatever custom imagemagick transformations
you need. Transformed assets should use a simple workflow for
approval, and then place them in another space, which would be
essentially your Digital Asset Library of approved corporate assets.
2. End-users can browse this digital library and using the clipboard
copy and paste any number of assets they want into their web
project. Then, they can create content using a form and reference.
In the ideally world we'd allow them to browse regular spaces to
statically reference fixed assets in the library or import into the
web project; we don't enable that now, although it is a to-do.
3. End-users alternatively can use the file-picker to upload a new
image in their web project, which they can upload directly from
the digital asset library presuming they have a CIFS mounted drive.
This would be a workaround for the last point above in #2.
Now, you can also just put digital assets in a web project and use imagemagick. Because web project folders do not yet support rules ala spaces, instead of writing a rule to call imagemagick for transformation, you'd instead configure a workflow to match on a particular file-extension and have a custom workflow that implemented a custom action to invoke imagemagick. What's nice about this is that in your custom workflow you can have a start task that captures on the transformation parameters a business user might want for an asset, and then at submit time have all the appropriate renditions generated in a reviewer's sandbox for potential approval. This puts more power in the hands of business users to specify what types of transformations they want on an asset when uploading into the system, and is a great use of our advanced workflow, sandboxes, and imagemagick engine.
A last way to do this is to capture the transformation options for a referenced asset directly in the web form itself. Then, in your Freemarker template, when you transform the XML, have a custom call-out to imagemagick passing the transformation parameters captured within the form data so that the generated page has exactly the image you need. This is probably the best solution ultimately - that way, business users can each reference the same asset, but for different business users when accessing the form they can specify things like whether they want it in black or white, 100'x200' or 200'x300', etc.
So, a few options available to you. Really, all are completely valid and have different merits in different situations. We intend to have all of these options supported in the client in the future. The benefit of a system like Alfresco is that is very flexible; I guess the corresponding downside is that because we don't out of the box present just one way of doing things, it can be a bit of a barrier for proof-of-concepts. Like I said, we will address this … it's the proverbial issues of time and resource …
Kevin