Thank you for using Aspose products.
I have evaluated your presented scenario while using the latest version of Aspose.Imaging for .NET 2.1.0. I am afraid, the issue didn’t replicate on my end, in fact the results are exactly as desired. I would request you to please give a try to the latest build on your side. In case your problem persists please provide us a few samples for our review.
Thank you for writing back.
I am afraid, I am not clear about your requirement. If you wish to change the dimensions of an image then Image.Resize method can do it for you. It is up to your requirement if you wish to save the re-sized canvas as a new image or overwrite the changes to the loaded image. By preserve, you meant not to overwrite the changes to original image, for that, please call the overloaded version Image.Save method that accepts parameters, such as stream object or path to new image file. In case you call the version that does not accept any parameters then the changes will be saved on the originally loaded image.
For better elaboration, I would request you to please provide a sample image as well as desired results so we could guide to further in this regard.