How to check whether a named Asset Transform exists?
You can check for the existence of a transform within your controller (for example), as follows:

 if (craft()-&gt;assetTransforms-&gt;getTransformByHandle('jimbob')) {
      // Transform exists.
 } else {
      // Transform does not exist (null is returned).
 }


Unfortunately, there doesn't seem to be an equivalent service (such as craft.assetTransforms) for use within templates.

Stephen