1. Transform Image uses an affine transformation matrix to specify required transformation (see here for some common 2D transformations).
To resize an image to half it's original size (in both axis) you would use the following model:
2. There's no straightforward way to retrieve the size of an image, without displaying it first. If you do display the image, you can add <Width> and <Height> elements, as in the following screenshot and refer to them after the image display is populated.
You could possibly use this to load an image, retrieve its size and than hide it, but I do feel a dedicated plug-in is warranted, and therefore added feature request #227.
3. The size of a file can be retrieved using Miscellaneous/Get File Attributes. The file must reside on the server. To create the file url, use Miscellaneous/Create File URL.
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