Some more info. It seems that file_uri_target() is returning false, and that image_style_url() creates the url as url('image/generate/' . $style_name . '/' . $scheme . '/' . $target, array('absolute' => TRUE)), despite the fact that $target contains false rather than a uri. On 6/17/2010 4:28 PM, Jeff Greenberg wrote:

I have used the predefined image styles (thumbnail, medium, etc.) within views. As a result, I note that with a file path for node attachments of styles/default/files/field/image, the styled image exists in styles/default/files/styles/medium/field/image.

So now, I am inserting a php snippet into a block, to make use of a styled image. The api says that the path should be relative to the files path. My call is:

theme_image_style(array('style_name' => 'medium','path' => 'field/image/myimage.png','alt' => 'text'));

The resulting HTML is <img typeof="foaf:Image" src="http://mydomain.com/image/generate/medium//" alt="text" />

so, I assume that /image is a callback url rather than something that should exist in the file system. If not, that's the first issue. Then, the /medium// seems to be missing the file name.