images with transparent background automatically saving with white background
For some reason the handling of images on both of my macs with transparent backgrounds is 'odd', I can have an image with a transparent background which if I copy and try to move elsewhere when I paste it has a solid background.
Further if I try to save the image with a transparent background it saves it onto a white background.
I've noticed it for a few months (first when trying to update my photo watermark at the start of the year) first in preview, now trying to copy a graph from excel into keynote it is carrying a white background even though I have everything set to no fill.
Any help gratefully received because this is really frustrating
OS X El Capitan (10.11.3)