Pasting an image into axure does not maintain dimensions

When I import an image either by copying and pasting or by loading it inside an image widget the dimensions of the original image are not being preserved. My understanding would be that pasted images should maintain their original dimensions.

example:


The image I have is 469 x 247,

but when I import/paste it, it is resized to 357 x 198

What I usually do is to drag-n-drop the Image-widget onto the canvas and use its default width and height.
Then I just double click the image widget and select the image file I want to upload. That seem to keep the aspect ratio of my images.

Sometimes the images are big and then Axure asks if it should be optimized for better performance.