I post vintage graphics from time to time. These are usually in png format and can be re-sized to however large or small you want without further losing any quality.
All my vintage images are 50-100 years old and include vintage ads, postcards, and postage stamps.
Simply click on the graphic in the post - it'll bring you to another page with the same graphic.
Right click on the graphic image and 'save as'
Save it to the folder you want to store it in on your hard drive.
That's all there is to it!
All the vintage graphics can be viewed at once by going to my 'Labels' section in the sidebar and clicking on 'vintage graphics.'
Enjoy!