One of the best features of designing in the PNG format is that you can utilize transparent backgrounds.
This means you can have the color of the fabric appear through the image. The image on the left still has a background, while the image on the right has had the background removed.
Here are a couple of tutorials demonstrating how to remove the background color:
- Removing backgrounds in Gimp
- Removing backgrounds in Photoshop
- Removing backgrounds in GIMP
- Removing backgrounds in Procreate
Here’s a more detailed article on the Redbubble Blog: