How do I add a portrait (vertical) screenshot without black bars

[𝑵𝒖𝒘𝒂]

Hello, I'm trying to post a custom screenshot (portrait mode) which looks like this:
https://imgur.com/TQlN9Vh (How it looks like in the "Friend Activity section")

But whenever I tried to post one, black bars will appear around the image and make it smaller which then make it very displeasing to look at:
https://imgur.com/e9s5o2j

Is there a way to post these custom screenshots without the existing black bars like in the first image I shared?

[Maria]

Your pic doesnt look like its from a game.

Maybe you mean, artwork?

[𝑵𝒖𝒘𝒂]

It's a screenshot from a game which was cropped like in the first image, can't figure out how they upload it without the borders tho

[Stiles]

Hi! Did you find a solution?

[𝑵𝒖𝒘𝒂]

@Malia Hello, yes I did it was actually because the size of the image, in my case it was too small so black bars would appear in those uploads.

[𝑵𝒖𝒘𝒂]

Higher resolution would avoid the black bars