Canvas an image and finding the colours in use

[intellix]

Hey guys... I have a function that allows a user to alter the size of a <canvas> element that contains an image.

 

In order for it to resize properly I had to remove the old element and create the other, using the same image.

 

Each image only has transparent and one other colour. Is it possible to just..... getColours on the <canvas> image and apply it to the new one?

 

Thanks, Dom