Here’s a handy tool for generating a graphic containing virtually any credit card or payment logo courtesy of Merchant Equipment Store.
Just tell it the height of the graphic and which logos to include. By default the image will have a transparent background, but you can specify a colour (do you really want to limit where you can use the image??).
They email you the code to place on your website or, if you prefer, you can use the URL in their code to download the graphic and load it onto your site yourself.
NOTE: For those with secure sites, the link for displaying the image is HTTPS, so it won’t cause the browser to show your site as insecure.
Here are some examples and part of the interface: