Badge Icons through Gamification API

I'd like to show the badge icons for a player of the gamification system, but I'm facing a few issues:

- when I retrieve the player details, I get a list of badges and IDs for the images, but those are unique per player. Therefore, I cannot compare two badge IDs of two player to know whether they have the same badge or not. The ID of the badge itself would be more helpful instead of the per player ID (both for the badge and the image)

- when I then try to add the image to my public website through the GetPicture API, the image is not shown since it requires authentication. Since my website is public and I don't want to add any credentials in the HTML code, I cannot show the badge icons. The SCN people's bio pages use images that are hosted on amazon aws to deal with this issue, but those urls are not usable for me since they have no reference to the badge ID or anything alike.

- when I query the GetPicture API with a non existent image id, I do get a 404. However, since I would use this URL in an img tag in my html code, it would be better to get some blank or dummy image returned, not a 404 error. This way I would not see the browsers default "image not found" replacement, which looks like something broken immediately. A dummy image would be a more graceful fallback.

Can anybody give me some hints on how to deal with this? especially with the required authentication for the GetPicture API?

Thanks a lot!