The resulting image is a mind-boggling 4,637MB, with a resolution of 69,536 in width and 22,230 in height, totalling 1,545,785,280 pixels. That's 1.5 Gigapixels! 
To put this size into further context, an iPhone with an 8 Megapixel camera is 200 times less detailed then the image published.
So, the Andromeda galaxy has been downsized to 4K images for your quick consumption.
The images come in two distinct sets. The "Normal" versions have only been cropped and resized. The "Post-processed" versions has been de-noised as much as possible, resulting in a less grainy and smoother wallpaper.
Normal, Dual Monitor 4K
Normal, Single Monitor 4K, Low Contrast
Normal, Single Monitor 4K, High Contrast
Post-processed, Dual Monitor 4K
Post-processed, Single Monitor 4K, Low Contrast
Post-processed, Single Monitor 4K, High Contrast