Doesnt it have to stetch the image to fit? The image isnt the same height and the grid row aligns to the tallest element.
The other option is to edit the image so that it is the same height ratio.
I guess i dont understand what you are trying to do. Grid allows you to put things in boxes. But they fit in them.
One thought it you can make the image relative position. Scale it up and manually move it.
Do you have an example of what you are trying to do. Grid might not be the best option.
Always
Jeremy