Hi @Lindis, can you be more specific about why you require this (e.g. to create an overlay for visualization, to use for further processing/analysis elsewhere) and also what ‘export just this selection’ means?
I ask because there are many ways to interpret this, e.g.
- the selection should be filled or only shown as an outline (in which case, with what line thickness?)
- the original pixel values of the image should be included within the selection, or the interior should be something else
- the selection should retain the original RGB color, or give a binary mask (with transparent background)
- the export should be at the full resolution or downsampled
A script that supports all of these would be very complex, therefore it would be helpful to be as specific as possible so that a script could be made more quickly. Note that some existing export options are described here.
Your post implies that you already have a method that almost does what you want, but gives a white background rather than transparency. If you could specify what this method is that would be a helpful starting point.