Bash Script from Github not working

I found this interesting Bash-Snippets from Github. I downloaded it with the [code] button and extracted it manually. The "meme" bash outputs a jpg which is, corrupt and can't be viewed therefore. I checked the code but still can't pinpoint the reason, why it isn't working. I tried multiple PhotoViewer tools. For usage, i tried Code:$ ./meme -f test #outputs the filename as "test.jpg"
$ doge #background
$ Topline #toplineText
$ Bottomline #BottomlineTextThe other bashes, which i can profit from, are all functional, out of the box.